Anatomy GEM 201 Flashcards
The three main sub disciplines of anatomy are gross or macro anatomy, histology or micro anatomy and embryology or developmental anatomy.
Other sub disciplines include radiological ,surface,clinical and comparative anatomy.
Out of all these seven sub disciplines, which of them is:
1. Invovled in the shape, location, relationship with other structures of the body, parts of the organ,blood supply, venous draining and innervation?
2. Invovled in Denstitt and content of tissues when electrons are passed through
3. Focuses on studying the internal structure of Eid the body using surface landmarks. Example is using the fifth intercostal space midclavicular to palpate or identify Apex best of the heart or midclavicular 9th intercostal space for the gall bladder?
4. Invovled in studying the design of a structure of the body putting individuals at risk even though it’s a normal structure but that normal structure being there predisposes the person to some diseases. Example is inguinal hernia more common In men because of the pathway of the descent of the testes.
5. Which is involved in looking at the different layers or cells or different tissues that make up an organ?
6. Which focuses on how organs form,developmental stages of an organ?
- Gross
- Radiological
- Surface anatomy
- Clinical anatomy
- Histology
- Embryology
Explain how the primitive gut forms and around which week of development It forms
The anatomy of the body is studies grossly by Inspection palpation percussion auscultation dissection medical imaging
Note also that the right kidney is lower than the left due to the liver occupying the space above it and the right kidney is around the 12th rib and the left is around the 11th and 12th rib.
Both kidneys are related to the posterior abdominal wall muscles, including:
• Psoas major
• Quadratus lumborum
• Transversus abdominis
This positioning is clinically significant because the 12th rib can be used as a landmark for identifying the kidneys during a physical exam or procedures like a renal biopsy.
Clinical Anatomy – A Different Definition
Clinical anatomy is the study of how anatomical structures relate to medical practice, diagnosis, and treatment. It focuses on applying anatomical knowledge to understand diseases, perform medical procedures, and identify anatomical variations that may predispose individuals to certain conditions. Unlike basic gross anatomy, which studies the structure for learning purposes, clinical anatomy is directly linked to real-world patient care.
Example:
• Understanding inguinal hernias by studying the weakness in the abdominal wall.
• Using anatomical landmarks to perform procedures like central line insertion or lumbar puncture.
Formation of the Primitive Gut in Embryology
The primitive gut forms during the third and fourth weeks of embryonic development due to the process of longitudinal and lateral folding of the embryo.
Key Steps in Primitive Gut Formation:
1. Embryonic Folding
• Longitudinal folding causes the embryo to curve, pulling in part of the yolk sac into the body.
• Lateral folding brings the edges of the embryo together, closing the body wall and enclosing a portion of the yolk sac.
2. Division into Three Regions
The primitive gut is divided into:
• Foregut (e.g., pharynx, esophagus, stomach, duodenum)
• Midgut (e.g., small intestine, proximal colon)
• Hindgut (e.g., distal colon, rectum)
3. Closure of the Body Wall
• The remaining yolk sac connection narrows to form the vitelline duct, which later disappears.
4. Development of the Gut Tube
• The primitive gut tube is lined by endoderm, which later forms the epithelial lining of the digestive tract and associated glands.
This process is crucial for forming the digestive system, respiratory system, and some endocrine organs.
No, the foregut, midgut, and hindgut are formed slightly later, around week 4 of development.
Timeline of Primitive Gut Formation:
• Week 1-3: Germ layer formation (gastrulation) → The endoderm forms, which will later give rise to the gut tube.
• Week 4: Embryonic folding occurs, pulling part of the yolk sac into the embryo → This forms the primitive gut tube, which is then divided into:
• Foregut
• Midgut
• Hindgut
So, the actual division into foregut, midgut, and hindgut happens in week 4, not within weeks 1-3.
How to Remember Gastrulation & Folding (Lateral & Longitudinal)
1️⃣ Gastrulation – “The 3-Layer Cake” 🍰
Think of gastrulation as making a 3-layer cake, where the single-layered embryo turns into three germ layers (ectoderm, mesoderm, endoderm).
Mnemonic: “E-M-E” (Ectoderm, Mesoderm, Endoderm)
• Ectoderm → External structures (skin, nervous system)
• Mesoderm → Middle structures (muscles, bones, blood)
• Endoderm → Enteric (gut, lungs, liver)
Process: “Gastrulation is like Inviting a Guest”
• The epiblast cells move in (invaginate) → just like a guest enters a house.
• The primitive streak forms like a door where cells dive in.
• The three germ layers are arranged from outside to inside, like stacking layers in a cake.
2️⃣ Folding – “Rolling a Burrito” 🌯
Imagine the embryo is a flat sheet, and during folding, it rolls into a tube like making a burrito.
💡 Lateral Folding – “Hugging Itself” 🤗
• The sides of the flat embryo fold inward, bringing the edges together like wrapping a burrito.
• This forms the gut tube and closes the body wall.
• If this fails → defects like gastroschisis (intestines outside the body) can happen.
💡 Longitudinal Folding – “Head-to-Toe Curl” 🌀
• The head and tail bend forward, like curling into a ball.
• This helps form the head, heart, and tail regions.
• If this fails → abnormalities like cranial or caudal defects can occur.
Quick Summary Mnemonic:
• Gastrulation → “E-M-E” (3-layer cake formation)
• Lateral folding → “Hugging itself” (wraps around to form the gut tube)
• Longitudinal folding → “Head-to-toe curl” (bends forward to shape the body)
Would you like a simpler or more visual way to remember this?
Most anatomical terminologies have Greek and Latin origins.
What are eponyms ?
Which system if anatomical naming had the names in only Greek and Latin
Which anatomical naming system is currently used now?
Eponyms are names of diseases, anatomical structures, medical conditions, procedures, or discoveries that are derived from the names of people or places associated with them.
Examples in Medicine:
1. Anatomy:
• Fallopian tubes (from Gabriele Falloppio)
• Islets of Langerhans (from Paul Langerhans)
2. Diseases:
• Parkinson’s disease (from James Parkinson)
Le names of individuals rjay have been ascribed structured cuz they discovered those structures.
Nomina anatomica- most names were in only Greek and Latin
Terminologia anatomica was codified in 1998 to allow eponyms in addition to the Latin and Greek words.
Difference Between Anatomica Nomina and Terminologia Anatomica:
• Anatomica Nomina contained many eponyms and older terms.
• Terminologia Anatomica (TA) replaced it with more universal, Latin-based names, making anatomical communication clearer worldwide.
While Anatomica Nomina played a crucial role in early anatomical standardization, TA is now the global standard for anatomical terminology.
anatomical terms can be composed of one or more of the ff:
- one or more roots joined together. Example is tachy joined to cardia, inter joined to vertebral, gastro joined to entero joined to logy
- roots can be joined by vowels. Example, chrom is joined to some by an o making chromosome. Cardi is joined to my and my is joined to pathy using two os making cardiomyopathy. Fus is linked to form by an I making fusiforme which means a spindle shaped structure
- use of prefix to be added to the root word. Example is epi (before) joined to gastric. Endo (inside) joined to gastric. Hypo (below) joined to thalamus, di(two) joins to gastric, sub(below) joining to sub thalamus
- use of suffix to be added to the root word. Example is micros cope, micros copy(study and use of the microscope),micros copic (something you can use the microscope to see)
-use of acronyms and abbreviations. Example of acronyms are PET(positron emission tomography), SCALP(SCALP is a mnemonic that represents the five layers of the scalp:
1. S – Skin (outermost layer, contains hair follicles and sebaceous glands)
2. C – Connective tissue (dense, highly vascularized, contains nerves)
3. A – Aponeurosis (galea aponeurotica, a tough fibrous layer connecting the frontalis and occipitalis muscles)
4. L – Loose connective tissue (allows movement of the scalp, but also a potential space for infections to spread)
5. P – Pericranium (periosteum covering the skull bones)
The “danger layer” is the loose connective tissue layer because infections can spread easily through it into the brain via emissary veins.), MALT(Mucosa associated lymphatic tissues)
Abbreviations(example DNA,MRI,etc)
- two different terms may be a noun and it’s adjective form. Example is brachium which means the arm and brachii which is qualifying which part of the arm or which means the structure is in the brachial region. So biceps brachii meaning the bicep is in the brachial region. Carpus which means wrist and carpi which means structure in the wrist. Yes, “carpi” can have two meanings depending on the context:1. Plural of carpus – Referring to multiple wrist bones (e.g., “The left and right carpi show no fractures”).2. Anatomical term for muscles associated with the wrist – Used in muscle names like flexor carpi ulnaris and extensor carpi radialis, where “carpi” refers to the wrist region these muscles act on.
So, “carpi” is both the plural of carpus and a term used in muscle anatomy
The. Digit which means fingers and toes and then digiti which means structures around the digit
- The adjective of the term may have singular and plural forms. Example is digit for structures related to one digit and digitorum for structures related to more than one digit.
- Terms may be positive, superlative and comparative. Example is magnus major and Maximus. So in increasing or decreasing order. Big bigger biggest. Gluteus minimus, medius and Maximus. Pectoralis major and pectoralis minor
- Some terms indicate possession. Example is rectus abdominis where a dominos means the abdomen area.
The digastric muscle is called “digastric” because it has two bellies (“di-” means two, and “gastric” means belly). Unlike most muscles, which have a single belly, the digastric muscle has:
1. Anterior belly (from the mandible)
2. Posterior belly (from the mastoid notch of the temporal bone)
These two bellies are connected by an intermediate tendon that attaches to the hyoid bone, allowing coordinated movement for jaw opening and swallowing.
In language and grammar, adjectives can describe things in different degrees of intensity or comparison. These degrees are:
1. Positive → Describes something in its basic form (e.g., “big,” “long”).
2. Comparative → Compares two things (e.g., “bigger,” “longer”).
3. Superlative → Describes the most extreme form (e.g., “biggest,” “longest”).
Latin anatomical terms also follow this pattern:
Example with “Long”
• Positive → Longus (long) → Extensor carpi radialis longus (long muscle in the wrist)
• Comparative → Longior (longer) → Rare in anatomical terms, but follows the rule
• Superlative → Longissimus (longest) → Longissimus thoracis (longest muscle in the back)
Another example:
1. Positive → Magnus (big) → Adductor magnus
2. Comparative → Major (bigger) → Pectoralis major
3. Superlative → Maximus (biggest) → Gluteus maximus
What About Minimus, Medius, and Maximus?
• Minimus (smallest) → Gluteus minimus
• Medius (middle-sized) → Gluteus medius
• Maximus (largest) → Gluteus maximus
These do not follow the usual positive-comparative-superlative pattern. Instead, they are just names that indicate size ranking,
Singular and Plural Adjective Forms:
• Muscle/tendon related to one finger or toe → Flexor digiti minimi
• Muscle/tendon related to multiple fingers or toes → Flexor digitorum superficialis
• Muscle/tendon related to one rib → Levator costae brevis
• Muscle/tendon related to multiple ribs → Levatores costarum longi
Here are more anatomical terms and their corresponding adjectives:
1️⃣ Arm & Hand
• Brachium → Brachii (upper arm)
• Antebrachium → Antebrachii (forearm)
• Carpus → Carpi (wrist)
• Digitus → Digiti (finger/toe)
• Manus → Manus (hand)
2️⃣ Leg & Foot
• Femur → Femoris (thigh)
• Crus → Cruris (leg)
• Pes → Pedis (foot)
• Tarsus → Tarsi (ankle)
3️⃣ Head & Neck
• Cranium → Cranialis (skull)
• Facies → Facialis (face)
• Cervix → Cervicis (neck)
• Nasus → Nasalis (nose)
• Oculus → Oculi (eye)
4️⃣ Trunk & Thorax
• Thorax → Thoracis (chest)
• Abdomen → Abdominis (abdomen)
• Dorsum → Dorsi (back)
• Lumbus → Lumborum (lower back)
5️⃣ Other Regions
• Gluteus → Glutei (buttocks)
• Inguen → Inguinalis (groin)
• Cubitus → Cubiti (elbow)
• Humerus → Humeri (upper arm bone)
Would you like more specific examples?
Under plural singular adjective possessive forms of anatomical terms, what is the plural of axilla, thorax, lumen, cortex,epididymis
Axilla- axillae
Thorax- thoraces
Lumen- lumina
Cortex- cortices
Epididymis - epididymides
State the anatomical reference for :
a man and
a woman (ethnicity, age,weight and height, plus two other things)
An anatomical reference man is a Caucasian of 20-25 years, average weight of 70kg and average height of 1.7m or 170cm living in an environment with ambient temperature and engaging in slight bodily activities
An anatomical reference woman is a Caucasian of 20-25 years, average weight of 65kg and average height of 1.65m or 165cm living in an environment with ambient temperature and engaging in slight bodily activities
Ambient temperature in this context means a stable, moderate environment (around 20–25°C) where the body functions normally without stress.
The name given to the reference and standard position used to describe the relationship of body structures is called?
Anatomical position
The anatomical position includes lying down with both feet flat on the floor with the head slightly elevated and neck straight, forearm in supine position and plantar is anterior. True or false.
The anatomical position includes standing with both feet flat on the floor with the head slightly elevated and neck straight, forearm in supine position and plantar surface of feet is anterior or inferior
False.
The correct anatomical position is:
• Standing upright (not lying down).
• Feet flat on the floor and slightly apart.
• Head level, facing forward.
• Arms at the sides with palms facing forward (forearm in supine position).
• Feet pointing forward (plantar surface is inferior, not anterior).
So, the statement is incorrect because it says “lying down” and “plantar is anterior,” which are both not part of the anatomical position.
In the normal anatomical position, a person stands upright with:
• The face and palms facing forward (anterior).
• The feet flat on the ground with toes pointing forward.
The plantar surface (sole of the foot) faces downward, toward the ground. Since inferior refers to a position below in anatomical terms, the plantar surface is considered inferior rather than anterior, which refers to the front of the body.
Give example of structures that can take different positions
Which position of the penis is the most correct anatomical position. Erect or flaccid?
Example 2: The Forearm
• In anatomical position, the palms face forward (supination).
• If you rotate the forearm so the palms face backward, this is called pronation.
• The forearm can be in two different positions (supinated or pronated), but in anatomical position, it must be supinated.
Example 3: The Foot
• In anatomical position, the sole (plantar surface) faces downward (inferior).
• If you lie on your back and lift your leg, the sole may now face backward (posteriorly).
• The foot’s position changes, but in anatomical position, the sole must face downward.
Example 4: The Scapula (Shoulder Blade)
• When the arms are at rest, the scapula lies flat on the back.
• When you push your shoulders forward (protraction), the scapula moves around the ribs and is more visible from the front.
• It changes position with movement, but its anatomical reference is at rest on the back.
So in conclusion, if a part of the body takes a different position from what is the actual anatomical position, you must describe it relative to the anatomical position. Let’s say the head has rotated. It is not in the normal position so looking at or relative to what we know as the normal anatomical position, it has rotated and is no longer was we know.
So we won’t say the head has pronated. We will say it has rotated relative to what we know is the correct anatomical position.
The penis takes its correct anatomical position from the erect position.
Okay, let’s take this step by step.
Understanding “Dorsum” Simply
1. Dorsum always refers to the “back” side of a structure.
• Hand: The back of your hand (not the palm) is the dorsum of the hand.
• Foot: The top of your foot (not the sole) is the dorsum of the foot.
2. The Rule in Anatomy:
• The dorsal side of a structure should align with the dorsal side of the body (the back).
• The ventral (front) side of a structure should align with the front of the body.
Now, Let’s Look at the Penis
- Flaccid (Soft) Penis:
• The top of the penis (dorsum) is pointing forward and downward, not in the same direction as the back of the body.
• This is not how dorsal surfaces normally align in anatomy.
• If we described it in this position, the dorsum of the penis would be facing forward, unlike the dorsum of the hand, back, and foot, which all face backward. - Erect Penis (Hard):
• When erect, the top (dorsum) of the penis is now facing upward toward the belly.
• This means its dorsum is now aligned in the same way as the back of the body, back of the hand, and top of the foot.
• So in anatomical position, we use this erect position to keep consistency with the definition of dorsum.
Key Takeaway:
The erect position is used in anatomy because it aligns the dorsum of the penis with other dorsal surfaces of the body. If we used the flaccid position, the dorsum of the penis would face the wrong way compared to other dorsal structures.
Let me know which part still seems unclear!
So in conclusion, the dorsum back of your hands and feet must align to the back while the front of your hands and feet must align to the front. The dorsum or back of the penis is the top of the penis and when it’s flaccid, it’s pointing forward or ventral in the direction of the ventral parts of the palms and feet instead of backward or dorsal. But when it’s erect, the dorsum has lifted like it’s going backwards
Why is the top of the penis “dorsal”?
1. Consistency with Other Body Parts
• The dorsum (back) of the hand is the opposite of the palm.
• The dorsum (top) of the foot is the opposite of the sole.
• The dorsum of the penis follows the same logic: it’s the opposite of the underside (where the urethra runs).
The underside (where the urethra is) is functionally different and faces ventrally (toward the front of the body in anatomical position). Since the dorsal side is always opposite to the ventral side, the top of the penis is considered dorsal instead of the underside.
Yes! The underside of the penis is considered ventral because the urethra runs along that side. Since the urethra is a continuation of the body’s ventral (front) side, the part of the penis where it is located is also called ventral.
Meanwhile, the top of the penis is called dorsal because it is opposite to the ventral side, just like how the back of the hand and foot are considered dorsal.
What are anatomical variations?
State the different variations in the structure of the kidney,heart and stomach
Anatomical Variations
Example is psoas minor muscle not being seen in all humans.
Anatomical variations are natural differences in body structure that occur between individuals. These variations are not abnormalities or diseases but rather differences in size, shape, position, or presence of certain structures. They are important in clinical practice because they can affect diagnosis, surgery, and medical procedures.
Specific Variations in the Stomach, Kidneys, and Heart
1. Stomach Variations
• Shape and Position: The stomach can vary in shape (e.g., J-shaped, elongated, or more horizontal). Some people have a high-placed stomach (hypersthenic) or a low-placed stomach (asthenic).
• Pyloric Variations: The pylorus (exit of the stomach) may be more to the right or lower than usual.
• Accessory Folds: Some individuals have extra mucosal folds in the stomach, which can sometimes be mistaken for pathology on imaging.
2. Kidney Variations
• Horseshoe Kidney: The two kidneys are fused at the lower poles, forming a U-shape across the midline.
• Pelvic Kidney: One kidney fails to ascend and remains in the pelvis instead of its usual position in the abdomen. If you’re looking for the second kidney and you don’t see it in the abdomen, check the pelvis.
• Duplicate Ureters: Some people have two ureters draining a single kidney instead of one.
• Unilateral Kidney (Agenesis): Some individuals are born with only one kidney (unilateral renal agenesis).
3. Heart Variations
• Dextrocardia: The heart is positioned on the right side instead of the left.
• Persistent Left Superior Vena Cava: An extra vein that drains blood into the heart remains present from fetal development.
• Aortic Arch Variants: Some people have an abnormal branching pattern of the aortic arch, affecting blood flow to the head and arms.
• Bicuspid Aortic Valve: Instead of having three cusps, the aortic valve has only two, which can lead to valve problems over time.
These variations are clinically significant because they may affect medical imaging, surgery, and treatment planning.
Anatomical Variations in the Heart: Aortic Arch Branching
The aorta branches into the ascending descending and arch of aorta.
The normal aortic arch gives off three main branches:
1. Brachiocephalic trunk (divides into the right subclavian and right common carotid arteries)
2. Left common carotid artery
3. Left subclavian artery
However, variations in this branching pattern are common and can impact blood flow, imaging, and surgical procedures.
Common Aortic Arch Variations
1. Bovine Aortic Arch
• The left common carotid artery arises from the brachiocephalic trunk instead of directly from the aorta.
• More common in some populations and usually has no clinical significance unless involved in vascular diseases.
2. Left Vertebral Artery Originating from the Aortic Arch
• Normally, the vertebral arteries arise from the subclavian arteries.
• In some individuals, the left vertebral artery arises directly from the aortic arch, creating an additional fourth branch.
3. Aberrant Right Subclavian Artery (ARSA)
• Instead of coming from the brachiocephalic trunk, the right subclavian artery arises directly from the aortic arch as the last branch and passes behind the esophagus.
• This can sometimes compress the esophagus, leading to difficulty swallowing (dysphagia lusoria).
4. Double Aortic Arch
• A rare condition where the aorta splits into two arches that encircle the trachea and esophagus, potentially causing breathing or swallowing difficulties.
5. Right Aortic Arch
• Instead of arching over the left bronchus, the aorta arches over the right.
• Often associated with congenital heart defects like Tetralogy of Fallot.
These variations are mostly asymptomatic but can become important in cardiac surgery, catheterization, and imaging procedures.
Stomach Variations Based on Tone and Shape
1. Orthotonic Stomach – The normal stomach shape with a gentle curve and good muscle tone.
2. Hypotonic Stomach – A stomach with reduced muscle tone, leading to a more elongated shape and slower emptying.
3. Atonic Stomach – A stomach with very weak or absent muscle tone, causing significant distension and poor motility.
4. Hypertonic Stomach – A stomach with increased muscle tone, appearing more contracted and sometimes J-shaped.
Relations of the Stomach
The stomach is located in the left upper quadrant of the abdomen and is closely related to the following structures:
• Posteriorly: Left kidney, left adrenal gland, pancreas, and spleen
• Superiorly: Diaphragm
• Anteriorly: Liver and anterior abdominal wall
• Inferiorly: Transverse colon
How does the variations in the stomach locations and types affect digestion?
Look at a pic of the diff variations
Hypertonic stomach → Shorter, more curved, and higher up in the abdomen.
• Hypotonic stomach → More elongated, stretched, and lower due to reduced muscle tone.
• Atonic stomach → Very stretched and sagging, with extremely weak muscle tone.
• Orthotonic stomach → The normal J-shape, balanced tone, and moderate positioning.
How Stomach Variations Affect Digestion
1. Hypertonic Stomach (Shorter, High, More Curved)
• Effect on Digestion: Food moves quickly through the stomach due to strong muscle tone.
• Possible Issue: May lead to faster gastric emptying, which can sometimes cause reduced nutrient absorption.
2. Hypotonic Stomach (Elongated, Lower Position)
• Effect on Digestion: Food stays in the stomach longer due to reduced muscle tone.
• Possible Issue: Can lead to slower digestion and feelings of bloating or early satiety (feeling full quickly).
3. Atonic Stomach (Severely Stretched, Weak Muscle Tone)
• Effect on Digestion: The stomach has poor motility, meaning food may stay too long before passing to the intestine.
• Possible Issue: Increased risk of gastric retention, fermentation of food, and bloating. Severe cases may lead to gastroparesis (delayed stomach emptying).
4. Orthotonic Stomach (Normal J-Shape, Balanced Tone)
• Effect on Digestion: Food moves through the stomach at a normal rate with efficient mixing of digestive juices.
• No major issues unless affected by disease.
Would you like more details on how these variations are diagnosed?
Which anatomical plane divides the body into anterior and posterior ?
Which divides it into superior and inferior?
Which divides it into left and right?
We cut the body according to these anatomical planes
Why Won’t You See the Uterus in a Transverse Section of the Abdomen?
What anatomical Planes Does MRI Mainly Use?
• The coronal (frontal) plane divides the body into anterior (front) and posterior (back) parts.
• The transverse (horizontal or axial ) plane divides the body into superior (upper) and inferior (lower) parts.
• The sagittal plane divides the body into left and right parts by cutting along the long axis of the body.
• If it divides the body equally into left and right halves, it is called the midsagittal (median) plane.
• If it divides the body unequally, it is called a parasagittal plane.
Additional Planes:
4. Oblique Plane – A diagonal plane that cuts the body at an angle (not perfectly horizontal or vertical).
5. Longitudinal Plane – Any plane that runs along the long axis of the body (includes sagittal and coronal planes).
6. Radial & Ulnar Planes (specific to the hand) – Used to describe movements and imaging of the forearm.
7. Plantar & Dorsal Planes (specific to the foot) – Used in podiatry to describe foot movements.
Why Won’t You See the Uterus in a Transverse Section of the Abdomen?
A transverse (horizontal) section of the abdomen does not typically show the uterus because the uterus is located in the pelvic cavity, which is below the abdomen. If the cut is made at the level of the abdomen, it will include structures like the intestines, kidneys, and liver, but not the uterus. To see the uterus in a transverse section, the imaging must be taken at a lower level, including the pelvic region.
Will a Transverse Section of the Pelvis Show the Uterus?
Yes! A transverse (axial) section of the pelvis will show the uterus, because the cut is taken at a lower level that includes pelvic organs. This is different from a transverse section of the abdomen, which is too high to capture the uterus.
What Planes Does MRI Mainly Use?
MRI primarily provides images in the transverse (axial) and coronal planes, but it can also produce sagittal images. The choice of plane depends on what the doctor wants to examine:
• Transverse (axial) – Common for brain, abdomen, and pelvic scans.
• Coronal – Often used for spine, joints, and chest imaging.
• Sagittal – Used for the brain, spine, and pelvic organs like the uterus.
Many MRI machines allow multi-planar reconstruction, meaning a scan taken in one plane can be adjusted to view in other planes as well.
1.What is the name given to the anatomical term which means toward the nose or the forehead
2.What is the name given to the term that talks about the front part of the body towards the belly?
3.What is the name of the term given to talking about the back or the spine?
4:What is the name of the term given to toward the ventral side ?
5.The name of the term given to toward the dorsal side?
What is the opposite of cephalic?
Refresh your memory on anatomical terms from PA like inferior, contralateral, ipsilateral,medial, lateral, etc. Note that the ulnar is medial while the radius is lateral (radius is remote. Remote is far away so far away from body which is lateral)
“Frontal” refers to the forehead region itself, while rostral means toward the nose or forehead, especially when describing structures in the brain or head.
For example:
• The frontal bone is the bone of the forehead.
• The rostral part of the brain is toward the nose and forehead.
So, frontal is a region, while rostral describes direction.
- Rostral
- Ventral (not anterior. Though they mean the same but in the context of this question, say ventral)
3.Dorsal
4: anterior - Posterior
The opposite of cephalic is caudal
Note: • The eyelid is rostral to the eyeball because it is positioned toward the nose and forehead.
• The eyeball is cephalic to the lower eyelid because it is positioned higher on the body (closer to the head).
Let me know if you need a simpler explanation!
You can have max of three anatomical directional terms in one sentence.
Note: unilateral contract of the Sternocleidomastoid muscles causes contralateral rotation of the face and ipsilateral lateral flexion of the neck.
See pictures of all these movements. ESP for hip, knee, feet, arms movements
Anatomical movements occur only at the joints. Know the angles at each joint to determine if flexion or extension has occurred.
What is extensions
What is flexion
What is hyper extension
What is zero position
What is plantar flexion
What’s the difference between lateral flexion and extension?
What is abduction? What is addiction?
What is the reference position of the fingers?
What is the reference position of the toes to determine if it’s flexion or extension or whatever?
Extension of the feet is called dorsi extension true or false
Definitions and Explanations:
1. Extension – A movement that increases the angle between two body parts. Example: Straightening the elbow or knee.
2. Flexion – A movement that decreases the angle between two body parts. Example: Bending the elbow or knee.
3. Hyperextension – Extension beyond the normal anatomical position. Example: Bending the neck backward beyond its neutral position.
4. Zero Position – The anatomical position, where all joints are in a neutral state, from which movements like flexion, extension, abduction, etc., are measured.
5. Plantar Flexion – Moving the foot downward, away from the shin, as in pointing the toes (like pressing a gas pedal).
6. Difference Between Lateral Flexion and Extension
• Lateral Flexion – Bending the spine or neck sideways (left or right).
• Extension – Returning the spine or neck to the upright (neutral) position or moving it backward.
7. Abduction – Moving a limb away from the midline of the body. Example: Raising the arms or legs sideways.
8. Adduction – Moving a limb toward the midline of the body. Example: Bringing the arms or legs back toward the body.
9. Reference Position of the Fingers – Fingers are considered to be in extension when they are straight (in anatomical position). Flexion occurs when you curl them. The reference position for the fingers is the middle finger.
10. Reference Position of the Toes – Toes are in extension when they are straight and in line with the foot. Flexion occurs when they are curled downward. Reference position for the toes is the big toe.
11. Extension of the feet is called Dorsi Extension – True or False?
• False – The correct term is Dorsiflexion, which means lifting the foot upward toward the shin.(this is extension yes but it’s not called extension but called dorsiflexion while pushing the feet downward will be plantar flexion cuz under the feet is plantar. You plant your feet on the ground so plantar)
- Difference Between Extension and Hyperextension
• Extension: Moves a joint from a flexed position back to the zero position (neutral anatomical position). Example: Straightening the knee after bending it.
• Hyperextension: Moves a joint past the zero position. Example: Bending the neck or lower back backward beyond its normal range. - How Movements Are Measured From the Zero Position
The zero position is the anatomical position (standing upright, palms forward). All movements are described as deviations from this position.
• Flexion: Measured as movement forward or decreasing the joint angle from zero position.
• Extension: Measured as movement back to zero position from flexion.
• Hyperextension: Measured as movement past zero position in the opposite direction.
• Abduction/Adduction: Measured from how far a limb moves away from or toward the midline.
• Rotation: Measured based on movement around an axis (e.g., turning the head left or right).
- Difference Between Lateral Flexion and Lateral Extension
• Lateral Flexion: Bending a structure sideways away from the midline. Example: Tilting your head or spine to the left or right.
• Lateral Extension: Returning the structure back to the zero position after lateral flexion.
Lateral flexion mostly applies to the spine and neck since these are the main body parts that can bend sideways.
No, raising your leg is not extension; it depends on the direction of movement. Let’s break it down clearly for each body part.
Understanding Flexion and Extension in Different Body Parts
Think of flexion as bending or decreasing the angle of a joint and extension as straightening or increasing the angle back to the neutral position.
- Arms (Shoulder and Elbow)
• Flexion: Moving the arm forward (e.g., raising it in front of you) or bending the elbow (e.g., bringing your hand toward your shoulder). Imagine a 180 degree angle on your arm. Bringing your hand to your shoulder will decrease that angle that’s why it’s flexion
• Extension: Moving the arm backward (past the body) or straightening the elbow (bringing the forearm back down).
• Hyperextension: Moving the arm too far backward (beyond normal range). - Legs (Hip and Knee)
• Hip Flexion: Lifting the leg forward (e.g., raising your thigh when walking). There’s an angle between your thigh and abdomen. Maybe 180. Lifting your leg reduces this angle.
Knee flexion and extension work opposite to the hip:
Knee Flexion
• Bending the knee (bringing the heel toward the back of your thigh) → Angle decreases → Flexion (angle is maybe 180 on back of leg when standing. If you sit down, it reduces the angle at the back of your leg where the popliteal area is to 90 degrees .
• Example: Sitting down, squatting, or kicking backward
Knee Extension
• Straightening the knee (returning the leg to a straight position) → Angle increases → Extension
• Example: Standing up, kicking forward
Why is it opposite to the hip?
• The knee is a hinge joint, and in anatomical position (standing), it is already extended.
• To flex the knee, you must bend it backward, reducing the angle.
• To extend the knee, you must straighten it, increasing the angle.
💡 Easy Trick:
• Flexion = Bending (heel moves toward the back)
• Extension = Straightening the knee
• Hip Extension: Bringing the leg back to the neutral position or moving it backward (e.g., pushing your leg behind you). • Hyperextension: Moving the leg too far backward (beyond normal range). • Knee Flexion: Bending the knee backward (e.g., when squatting or kicking back). • Knee Extension: Straightening the knee back to zero position (standing straight). • Hyperextension: Pushing the knee too far back, beyond straight.
- Feet (Ankle Movements)
• Plantar Flexion: Pointing the toes downward (e.g., pressing on a gas pedal).
• Dorsiflexion: Lifting the toes upward (e.g., walking on your heels).
How to Know If It’s Flexion or Extension?
1. If the movement reduces the angle → Flexion
2. If the movement increases the angle back to normal → Extension
3. If the movement goes beyond normal straight position → Hyperextension
So, if you raise your leg forward, you’re doing hip flexion, not extension. If you bring it back down or push it behind you, that’s hip extension.
Hip flexion brings the leg forward because flexion decreases the angle between the thigh and the torso.
Think of it this way:
• When you lift your leg forward (like when kicking a ball or taking a step), the angle between your thigh and abdomen decreases → This is flexion.
• When you bring your leg back down or move it behind your body, the angle increases → This is extension.
Why is it like this?
• Anatomically, zero position (neutral) is when you are standing upright with your legs straight.
• Any movement that reduces the angle at the hip joint (bringing the thigh closer to the abdomen) is flexion.
• Any movement that increases the angle (moving the thigh away from the abdomen) is extension.
💡 Quick way to remember:
• Flexion = Forward (reducing the angle)
• Extension = Backward (increasing the angle back to neutral)
What is radial flexion, ulnar flexion,palmar abduction of thumb? Opposition of thumb? And why is opposition of the thumb important?
The deep transverse metacarpal ligament binds in the hand something sormthing so the opponens pollicis in the thumb allows the thumb to oppose.
What is pronation?
What is supination?
What is protraction?
What is retraction?
What is circumduction?
What is medial or internal rotation?
What is lateral or external rotation?
Elevation and depression ?
How is the foot pronated?
Hand & Thumb Movements
Radial & Ulnar Flexion (Deviation)
• Radial Flexion (Radial Deviation): Moving the wrist toward the radius (thumb side).
• Example: Waving with your hand tilting toward the thumb.
• Ulnar Flexion (Ulnar Deviation): Moving the wrist toward the ulna (little finger side).
• Example: Tilting your hand toward your pinky.
Palmar Abduction of the Thumb
• Moving the thumb away from the palm in a forward direction (perpendicular to the palm).
• Example: Moving your thumb forward, like when you reach to pick up a bottle.
Opposition of the Thumb
• Moving the thumb across the palm to touch the fingertips.
• Why is it important?
• Allows grasping and pinching, making fine motor skills possible (e.g., writing, buttoning clothes).
• The opponens pollicis muscle plays a key role, and its action is restricted by the deep transverse metacarpal ligament, which binds the fingers together but allows thumb movement.
Other Movements
Pronation & Supination
• Pronation: Rotating the forearm so the palm faces downward (posteriorly in anatomical position).
• Example: Turning your hand to type on a keyboard.
• Supination: Rotating the forearm so the palm faces upward (anteriorly in anatomical position).
• Example: Holding a bowl of soup (“Supination = Holding Soup”).
Protraction & Retraction (Used for the jaw & shoulder)
• Protraction: Moving a body part forward/anteriorly.
• Example: Pushing your jaw or shoulders forward.
• Retraction: Moving a body part backward/posteriorly.
• Example: Pulling your jaw or shoulders back.
Circumduction
• A circular motion that combines flexion, extension, abduction, and adduction.
• Example: Making arm circles or moving your finger in a circle.
Medial (Internal) Rotation & Lateral (External) Rotation
• Medial Rotation: Rotating a limb toward the midline.
• Example: Turning your foot inward.
• Lateral Rotation: Rotating a limb away from the midline.
• Example: Turning your foot outward.
Elevation & Depression
• Elevation: Lifting a body part upward.
• Example: Shrugging your shoulders.
• Depression: Lowering a body part downward.
• Example: Relaxing your shoulders after shrugging.
Understanding Ulnar Flexion (Ulnar Deviation)
Flexion generally means reducing the angle of a joint, but in the case of ulnar flexion, it’s a sideways movement of the wrist, not a traditional bending motion like elbow flexion.
• The angle is reduced between the hand and the ulna (medial forearm bone).
• When you move your wrist toward the little finger (ulnar side), the hand bends toward the ulna, decreasing the angle on that side.
Think of it like tilting your hand inward toward your pinky rather than bending it forward or backward.
Foot Pronation
Pronation of the foot is different from forearm pronation because the foot doesn’t rotate in the same way.
Pronation of the foot involves three movements combined:
1. Eversion – The sole of the foot turns outward.
2. Dorsiflexion – The toes move upward slightly.(flexion)
3. Abduction – The foot moves slightly away from the midline.
Example:
• When you walk or run, your foot naturally pronates to absorb shock.
• In excessive pronation, the arch flattens too much, leading to overuse injuries.
Supination of the Foot (Opposite of Pronation):
1. Inversion – The sole of the foot turns inward.
2. Plantarflexion – The toes point downward slightly.(extension of foot cuz angle is on top part of the foot not behind it)
3. Adduction – The foot moves slightly toward the midline.
This movement pattern makes the foot more rigid, which helps in pushing off while walking or running.
What is inversion
What is eversion
What is medial excursion
What is lateral excursion
Definitions of Movements
1. Inversion
• The sole of the foot turns inward toward the midline and the heel stays down.
• Example: Standing on the outer edge of your foot.
• Opposite: Eversion (sole turns outward).
2. Eversion
• The sole of the foot turns outward, away from the midline and your heel raises. • Example: Standing on the inner edge of your foot.
3. Lateral Excursion
• Movement of the mandible (jaw) or lower jaw away from the midline and out , to the left or right.
• Example: Moving your jaw to the side while chewing.
• Opposite: Medial Excursion (returning to the midline).
4. Medial Excursion
• The jaw moves back toward the midline or inside after lateral excursion.
• Example: Returning the jaw to a neutral position after shifting it sideways.
These terms mainly apply to jaw and foot movements in anatomical descriptions.
Look at course outline to see if you’re missing something
In the organization of the human body, we have the chemical part(includes atoms and molecules), the organelles, the cellular level, the tissues, the organs, the organ system, the organism.
State the two main approaches to studying anatomy and their advantages and disadvantages
Approaches
1. Regional anatomy
A. Appendicular region- upper and lower limbs
B. Axial region: head and neck, trunk(thorax, abdomen, pelvis, perineum)
- Systemic anatomy:
There are 11 systems plus an immune system. It’s used to teach nurses and others while regional is used to teach med students.
Regional Anatomy
✅ Advantage: Helps understand the relationships that exist among structures (muscles, nerves, blood vessels) within a specific body region.
❌ Disadvantage: Does not provide a complete view of an entire system (e.g., learning only upper limb muscles may make it harder to understand the muscular system as a whole).
Systemic Anatomy
✅ Advantage: Gives a full understanding of a body system (e.g., learning all muscles together helps see how the muscular system functions as a whole).
❌ Disadvantage: Does not emphasize how different systems interact within a region or doesn’t show the relationship that exists among structures in a region. (e.g., studying all muscles together may overlook their relationship with nearby nerves and blood vessels in a specific region).
Systemic anatomy does show how muscles relate as a whole system, but it doesn’t focus on how they interact with other structures in a specific region (like nerves, blood vessels, and bones in the arm).
For example:
• Regional anatomy helps you see how the biceps brachii is positioned near the brachial artery and musculocutaneous nerve in the upper limb.
• Systemic anatomy teaches you about all muscles in the body together, but it doesn’t emphasize their local relationships with nearby structures.
So, regional anatomy helps with local functional understanding, while systemic anatomy gives a broader view of how an entire system works.
Yes, that makes sense. A disadvantage of regional anatomy is that it focuses only on structures within a specific area, so if you’re studying muscles in the upper or lower limb, you won’t learn about muscles in other parts of the body at the same time. This can make it harder to see how a system (like the muscular system) works as a whole.
What is the name given to the following parts of the body (mention the name anteriorly and the name posteriorly):
Head
Face
Neck
Chest
Sternum
Arm
Hand
Back
Wrist
Abdomen
Umbilicus
Butt
Groin
Place where the reproductive structures are at
The thigh
Knee
Leg
Feet
Ankle
Make sure you look at a picture so you know where each part of the body is called in regional anatomy
- Head & Neck
• Cranial – Anterior & Posterior (skull)
• Facial – Anterior (face)
• Frontal – Forehead
• Orbital – Eye region
• Nasal – Nose
• Oral – Mouth
• Buccal – Cheeks
• Mental – Chin
• Cervical – Anterior (front of neck)
• Nuchal – Posterior (back of neck) - Thorax (Chest & Upper Back)
• Acromial – Anterior & Posterior (shoulder)
• Thoracic – Anterior & Posterior (chest region)
• Pectoral – Anterior (chest)
• Sternal – Anterior (midline of chest)
• Mammary – Anterior (breast region)
• Scapular – Posterior (shoulder blade region)
• Interscapular – Posterior (between shoulder blades)
• Vertebral – Posterior (spinal column) - Abdomen & Lower Back
• Abdominal – Anterior (stomach region)
• Umbilical – Anterior (navel region)
• Pelvic – Anterior (lower abdomen)
• Inguinal – Anterior (groin)
• Lumbar – Posterior (lower back)
• Sacral – Posterior (base of the spine, above buttocks)
• Perineal – Posterior (between anus and external genitalia) - Upper Limb
• Axillary – Anterior (armpit)
• Brachial – Anterior & Posterior (upper arm)
• Antecubital – Anterior (front of elbow)
• Olecranal – Posterior (back of elbow)
• Antebrachial – Anterior & Posterior (forearm)
• Carpal – Anterior (wrist)
• Dorsum of Hand – Posterior (back of hand)
• Palmar – Anterior (palm)
• Digital – Anterior & Posterior (fingers) - Lower Limb
• Gluteal – Posterior (buttocks)
• Gluteal Cleft – Posterior (midline between buttocks)
• Gluteal Fold – Posterior (crease where buttocks meet the thigh)
• Coxal – Anterior (hip)
• Femoral – Anterior & Posterior (thigh)
• Patellar – Anterior (kneecap)
• Popliteal – Posterior (back of knee)
• Crural – Anterior of leg (shin or the leg(rem cruise as in walking))
• Sural – Posterior of leg (calf)
• Tarsal – Anterior (ankle)
• Calcaneal – Posterior (heel)
• Dorsum of Foot – Anterior (top of foot)
• Plantar – Posterior (sole of foot)
• Digital – Anterior & Posterior (toes)
Here are the regions with different names for anterior and posterior views:
Head & Neck
• Cervical (Anterior) / Nuchal (Posterior) – Neck
Thorax & Back
• Sternal (Anterior) / Vertebral (Posterior) – Midline of chest vs. spine
• Pectoral (Anterior) / Scapular (Posterior) – Chest vs. shoulder blade region
• Interscapular (Posterior only) – No anterior equivalent
Abdomen & Lower Back
• Abdominal (Anterior) / Lumbar (Posterior) – Stomach region vs. lower back
• Pelvic (Anterior) / Sacral (Posterior) – Lower abdomen vs. base of spine
• Inguinal (Anterior) / Perineal (Posterior) – Groin vs. area between anus and genitals
Upper Limb
• Antecubital (Anterior) / Olecranal (Posterior) – Front vs. back of elbow
• Palmar (Anterior) / Dorsum of Hand (Posterior) – Palm vs. back of hand
Lower Limb
• Patellar (Anterior) / Popliteal (Posterior) – Kneecap vs. back of knee
• Crural (Anterior) / Sural (Posterior) – Shin vs. calf
• Dorsum of Foot (Anterior) / Plantar (Posterior) – Top vs. sole of foot
These are the key regions where anterior and posterior names differ.
State the foramins in the body
Here are some common foramina in the body and their key structures:
Skull Foramina:
1. Foramen magnum – Spinal cord, vertebral arteries, and accessory nerve (CN XI).
2. Supraorbital foramen – Supraorbital nerve, artery, and vein.
3. Infraorbital foramen – Infraorbital nerve, artery, and vein.
4. Mental foramen – Mental nerve, artery, and vein.
5. Optic canal (foramen) – Optic nerve (CN II) and ophthalmic artery.
6. Superior orbital fissure – CN III (oculomotor), CN IV (trochlear), CN V1 (ophthalmic), CN VI (abducens), and superior ophthalmic vein.
7. Inferior orbital fissure – Infraorbital and zygomatic nerves, infraorbital artery, and vein.
8. Foramen rotundum – Maxillary nerve (CN V2).
9. Foramen ovale – Mandibular nerve (CN V3), accessory meningeal artery.
10. Foramen spinosum – Middle meningeal artery and vein, meningeal branch of CN V3.
11. Foramen lacerum – Nothing passes through directly (covered by cartilage in life).
12. Jugular foramen – Internal jugular vein, CN IX (glossopharyngeal), CN X (vagus), CN XI (accessory).
13. Internal acoustic meatus – CN VII (facial) and CN VIII (vestibulocochlear).
Pelvic Foramen:
14. Obturator foramen – Obturator nerve, artery, and vein.
Vertebral Foramina:
15. Intervertebral foramen – Spinal nerves exit.
16. Transverse foramen (in cervical vertebrae) – Vertebral arteries and veins.
A body cavity is a space in the body that forms from folding during embryonic development State the two main body cavities in the axial region
If an organ changes position, is it herniation? If not, what is it?
What is herniation?
How is the organ changing position different from anatomical variations?
1.Dorsal body cavity which is created by skeletal framework but not filled with bones.
Comprises of
A. Cranial cavity which is Anterior and has the brain
B. Posterior spinal cord or vertebral canal
Two Main Body Cavities in the Axial Region
The axial region of the body contains two major cavities:
- Dorsal Body Cavity (Located at the back, enclosed by bones)
• Formed by the skeletal framework (skull and vertebrae) but is not filled with bones—instead, it houses the central nervous system. dorsal body cavity was not formed by the skeletal framework. Instead, the cavity developed first during embryonic development, and then the skeletal structures (skull and vertebrae) grew around it to provide protection. So, the bones enclose the cavity, but they did not create it.
In short: The dorsal cavity existed first, and the skeletal framework formed around it for protection
Divided into:
• Cranial Cavity (Anterior) → Encloses the brain within the skull.
• Vertebral (Spinal) Cavity (Posterior) → Contains the spinal cord, enclosed by the vertebral column. - Ventral Body Cavity (Located at the front, contains soft organs). Larger than the dorsal cavity and divided by the diaphragm into two parts:
• Thoracic Cavity → Contains the lungs, heart, esophagus, and trachea.
• Abdominal Cavity → Houses digestive organs (stomach, liver, intestines, etc.).
• Pelvic Cavity → Contains the bladder, reproductive organs, and rectum.
The diaphragm which is a musculotendinous stretcher that separates the thoracic cavity and abdominal cavity. Organs will pass through or behind the diaphragm if they shift from the thorax to abdomen or Vice versa.
There’s no barrier between abdominal cavity and pelvic cavity so structures can transverse freely between them.
The bladder is in the pelvic in adults but is in the abdominal cavity in children but as children grow, it enters into the pelvic cavity. . When the bladder is full, it bulges into the abdominal cavity.
Your information is mostly accurate, but I’ll clarify and correct some points for precision:
1. The diaphragm is a musculotendinous structure that separates the thoracic and abdominal cavities – ✅ Correct.
• It serves as the primary muscle for respiration and has openings (foramina) through which structures pass between the thorax and abdomen.
2. Organs pass through or behind the diaphragm when moving between the thorax and abdomen – ✅ Correct.
• Some key structures that pass through or behind the diaphragm include:
• Esophagus (through the esophageal hiatus)
• Inferior vena cava (through the caval opening)
• Aorta (through the aortic hiatus)
• Vagus nerves and thoracic duct
3. There is no barrier between the abdominal and pelvic cavities, so structures can move freely between them – ✅ Correct.
• The abdominopelvic cavity is a continuous space, and there is no physical separation between the abdominal and pelvic cavities.
• This allows structures like the intestines, blood vessels, and ureters to extend freely between the two regions.
4. The bladder is in the pelvis in adults but in the abdomen in children, and as children grow, it enters the pelvis – ✅ Correct.
• In infants and young children, the urinary bladder is located in the abdomen because the pelvis is not yet fully developed.
• As the child grows and the pelvis enlarges, the bladder descends into the pelvic cavity.
5. When the bladder is full, it bulges into the abdominal cavity – ✅ Correct.
• A distended (full) bladder rises above the pubic symphysis, making it palpable in the lower abdomen.
Final Verdict:
✅ Your information is mostly accurate. Just be clear that the diaphragm does not block structures entirely but allows them to pass through specific openings. Also, the abdominopelvic cavity is a continuous space without a strict division.
No, a change in an organ’s position is not always herniation.
Herniation vs. Normal Positional Change:
1. Herniation → When an organ protrudes through an abnormal opening in a tissue or cavity where it is usually contained.
• Example: Hiatal hernia (stomach protrudes through the diaphragm into the thorax).
2. Normal Positional Change → Some organs naturally change position due to growth, posture, movement, or physiological conditions (e.g., breathing, digestion, or bladder filling).
• Example: The bladder moves up when full, but this is not a hernia.
Key Difference:
• Herniation involves an abnormal displacement, often through a weak spot in surrounding tissues.
• Normal position changes are expected and do not involve tissue damage or abnormal openings.
A normal position change of an organ is called physiological displacement or positional variation.
Examples:
• Bladder expansion → When full, the bladder moves upward into the abdominal cavity.
• Diaphragmatic movement → The liver and stomach shift slightly with breathing.
• Postural changes → The kidneys move slightly when lying down vs. standing.
These are normal and do not indicate pathology like herniation.
Yes, positional variation and anatomical variation are different concepts:
1. Positional Variation → Temporary or natural movement of an organ based on function, posture, or physiological conditions.
• Example: The bladder moves upward when full.
• Example: The diaphragm shifts with breathing.
2. Anatomical Variation → A congenital (born-with) difference in structure that is not a disease but a deviation from the typical anatomy.
• Example: Having an extra renal artery.
• Example: A bicuspid aortic valve instead of the usual tricuspid.
Key Difference:
• Positional variation is temporary and normal.
• Anatomical variation is a structural difference present from birth.
How is the folding done in embryonic development concerning the trilaminar disc
Trilaminar Disc and Body Folding in Embryonic Development
1. Trilaminar Disc Formation:
• Around week 3 of development, the embryo undergoes gastrulation, forming the trilaminar disc, which consists of three germ layers:
• Ectoderm (outer layer) → Forms skin, nervous system.
• Mesoderm (middle layer) → Forms muscles, bones, blood vessels.
• Endoderm (inner layer) → Forms the gut, liver, lungs.
2. Folding of the Embryo:
By week 4, the initially flat trilaminar disc undergoes two main types of folding to create the basic body shape:
• Longitudinal Folding (Head-Tail Folding)
• The head and tail bend forward due to rapid brain and spinal cord growth.
• This helps enclose the gut tube inside the body.
• Lateral Folding (Side-to-Side Folding)
• The sides of the embryo fold downward and inward.
• The ectoderm covers the outside, and the endoderm forms a tube inside (future digestive tract).
• This process encloses the body cavities, such as the pericardial (heart), pleural (lungs), and peritoneal (abdominal) cavities.
State the 11 body systems and the principal organs in each system.
What system is responsible for non verbal communication?
Which is responsible for water retention?
Which is responsible for being a physical barrier between internal organs and the outside?
Which four systems focus on acid base balance ?
Which system does motor control and sensation?
What’s the difference between the endocrine system and nervous system ?
Why are these two systems similar?
Which system is responsible for internal chemical communication and coordination?
Body systems are :
Functions of the Integumentary System (Skin, Hair, Nails, Cutaneous Glands)
1. Non-verbal Communication – Facial expressions and changes in body hair (e.g., goosebumps) help convey emotions.
2. Cutaneous Sensation – Detects heat, cold, touch, pressure, pain, and texture.
3. Water Retention – Prevents excessive water loss or absorption. The skin prevents excessive water retention by acting as a selective barrier.
• Keratinized Epidermis: The outer layer of the skin (stratum corneum) is made of dead, keratinized cells that are hydrophobic, preventing water from being absorbed into the body when exposed to liquids.
• Sebum (Oil Production): The sebaceous glands secrete oil that adds a waterproof layer, further preventing water from penetrating the skin.
• Tight Junctions: Skin cells are tightly packed with intercellular connections that block excessive water entry.
While the skin can absorb small amounts of water (e.g., through prolonged soaking), it largely prevents excessive swelling or fluid accumulation.
4. Physical Barrier – Protects internal organs from pathogens, UV radiation, and mechanical injury.
5. Thermoregulation – Regulates body temperature through sweat production and blood vessel dilation or constriction.
6. Vitamin D Synthesis – The skin helps produce vitamin D when exposed to UV light, which is essential for calcium absorption.
Skeletal system (bones , cartilage,ligaments)
The skeletal system does acid base balance and electrolyte balance. Bones and cartilage form the main skeletal system. Ligaments connect one bone to another at a joint. Cartilage covers ends of bones.
Muscular system: principal organs are the skeletal muscles.
They do heat production, guard the openings of the body(example is the oral tissue guards the oral cavity, the orbit is covered by obicularis oris)
Lymphatic system: lymph nodes vessels, lymphatic vessels, thymus,spleen,tonsils
Functions. In the recover of excess tissue fluid?(how)
Lymphatic system works with the immune system and circulatory system
Respiratory system functions for speech due to the larynx and then acid base balance
Urinary system: does regulation of blood volume and pressure, elimination of waste including excess water
Nervous system- brain , spinal cord, nerves, ganglia
Functions is motor control and sensation
Endocrine system: principal organs are testes, ovaries, pancreas, thymus, adrenal gland, parathyroid, pineal gland, thyroid, pituitary gland .
works like nervous system in controlling the body but does so using chemicals such as hormones while nervous system does it via electrical system.
Function of the endocrine system is for internal chemical communication and coordination.
Circulatory system: distribution of things, electrolyte and acid base balance. Why is the circulatory system important? It moves hormones to where they’re to be, waste to to where it’s supposed to go..
Digestive system: salivary glands, teeth, tongue, liver
Functions; liver causes metabolism of macromolecules, vitamins, minerals, synthesis of plasma proteins. Entire digestive does nutrient breakdown and absorption
Reproductive system:
Male: secretion of male sex hormones
Female: ovaries, dallopian tubes, mammary glands,uterus, vagina
Function is secretion of sex hormones, lactation, fetal nourishment .
Mammary gland is a modified sweat gland
Here’s an in-depth explanation of each system while keeping it concise:
- Skeletal System (Bones, Cartilage, Ligaments)
• Support & Protection: Bones provide structural support (e.g., the vertebral column supports posture), and protect organs (e.g., the skull protects the brain).
• Electrolyte Balance: Bones store calcium and phosphate, releasing them into the bloodstream when needed.
• Acid-Base Balance: Bones buffer pH by absorbing or releasing alkaline phosphate and carbonate ions.
• Movement: Bones act as levers for muscles (e.g., the humerus and femur help in limb movement).
• Blood Cell Formation: Red bone marrow produces red and white blood cells via hematopoiesis.
• Cartilage Function: Covers the ends of bones in joints to reduce friction and absorb shock (e.g., hyaline cartilage in the knee joint).
• Ligaments: Connect bones at joints to provide stability (e.g., the anterior cruciate ligament in the knee). - Muscular System (Skeletal Muscles)
• Movement: Muscles pull on bones to produce motion (e.g., biceps flex the elbow).
• Heat Production: Muscle contractions generate heat to maintain body temperature (e.g., shivering).
• Posture & Stability: Core muscles help maintain balance and posture.
• Guarding Body Openings: Sphincters control passage through openings (e.g., the orbicularis oris regulates the mouth opening, and the external urethral sphincter controls urine release). - Lymphatic System (Lymph Nodes, Lymphatic Vessels, Thymus, Spleen, Tonsils)
• Fluid Recovery: Returns excess tissue fluid to the bloodstream, preventing swelling (edema).
• Immunity: Lymph nodes filter pathogens, and white blood cells in lymph fight infections.
• Lipid Absorption: The small intestine’s lacteals absorb dietary fats into the lymphatic system before entering the bloodstream.
• Example: Swollen lymph nodes during an infection indicate an immune response. - Respiratory System (Nose, Pharynx, Larynx, Trachea, Bronchi, Lungs)
• Gas Exchange: Oxygen is absorbed into the blood, and CO₂ is expelled via alveoli in the lungs.
• Speech: The larynx (voice box) produces sound by vibrating vocal cords.
• Acid-Base Balance: Controls blood pH by adjusting CO₂ levels—excess CO₂ lowers pH (acidosis), while reduced CO₂ raises pH (alkalosis). - Urinary System (Kidneys, Ureters, Bladder, Urethra)
• Blood Volume & Pressure Regulation: The kidneys adjust water and sodium levels to regulate blood pressure (e.g., renin-angiotensin system).
• Waste Elimination: Kidneys filter out urea, creatinine, and excess water through urine.
• pH Balance: By excreting hydrogen ions and reabsorbing bicarbonate, the kidneys regulate blood pH. - Nervous System (Brain, Spinal Cord, Nerves, Ganglia)
• Motor Control: Sends signals to muscles for movement (e.g., lifting a hand).
• Sensory Processing: Detects and interprets stimuli (e.g., heat, pain, sound).
• Coordination & Communication: Transmits electrical signals quickly to regulate body functions. - Endocrine System (Testes, Ovaries, Pancreas, Thymus, Adrenal Glands, Parathyroid, Pineal Gland, Thyroid, Pituitary Gland)
• Chemical Regulation: Uses hormones to control body processes (e.g., insulin from the pancreas regulates blood sugar).
• Growth & Development: Growth hormone (GH) from the pituitary stimulates bone and muscle growth.
• Stress Response: Adrenal glands release cortisol and adrenaline to handle stress.
• Reproduction: Ovaries and testes secrete sex hormones (e.g., estrogen, testosterone). - Circulatory System (Heart, Blood Vessels, Blood)
• Transport: Delivers oxygen, nutrients, hormones, and removes waste.
• Electrolyte & pH Balance: Regulates levels of sodium, potassium, and pH (e.g., bicarbonate in the blood buffers pH).
• Thermoregulation: Blood vessels dilate or constrict to regulate body temperature. - Digestive System (Mouth, Esophagus, Stomach, Intestines, Liver, Pancreas, Gallbladder)
• Nutrient Breakdown & Absorption: Enzymes in the stomach and intestines digest food; nutrients are absorbed into the blood.
• Liver Function: Metabolizes macronutrients, stores vitamins, detoxifies substances, and synthesizes plasma proteins.
• Waste Elimination: Indigestible materials exit via feces. - Reproductive System
Male (Testes, Prostate, Penis, Seminal Vesicles, Vas Deferens)
• Sperm Production: Testes produce sperm and testosterone.
• Seminal Fluid: Seminal vesicles and prostate produce components of semen.
Female (Ovaries, Uterus, Fallopian Tubes, Mammary Glands, Vagina)
• Egg Production: Ovaries release eggs and produce estrogen and progesterone.
• Fetal Nourishment: The uterus supports pregnancy; mammary glands provide milk for infants.
• Mammary Glands: These are modified sweat glands that produce milk.
Would you like further details on any system?
Differences Between the Endocrine and Nervous Systems
• Mode of Communication: The endocrine system uses chemical signals (hormones), while the nervous system uses electrical impulses (neurotransmitters).
• Speed of Response: The endocrine system is slow (seconds to days), while the nervous system is fast (milliseconds).
• Duration of Effect: The endocrine system has long-lasting effects (hours to weeks), while the nervous system has short-lived effects (fractions of a second to minutes).
• Target Area: The endocrine system affects multiple organs (widespread), while the nervous system affects specific cells/tissues.
• Type of Control: The endocrine system regulates long-term processes (growth, metabolism, reproduction), while the nervous system controls rapid responses (reflexes, muscle movement).
• Mode of Transport: The endocrine system sends hormones through the bloodstream, while the nervous system transmits impulses through neurons.
Why Are the Endocrine and Nervous Systems Similar?
• Both control body functions like metabolism, stress response, growth, and homeostasis.
• Both use chemical signals (hormones for the endocrine system, neurotransmitters for the nervous system).
• They work together, with the hypothalamus (brain) regulating the pituitary gland, which controls many endocrine functions.
• Both influence behavior and mood (e.g., serotonin affects emotions, while cortisol influences stress responses).
Example of Interaction:
During stress, the nervous system quickly triggers the “fight or flight” response using neurotransmitters like norepinephrine. The endocrine system follows up by releasing cortisol from the adrenal glands for a prolonged stress response.
What are the anatomical divisions of the nervous system ?
What are the functional divisions of the nervous system?
Anatomical:
A. CNS: Brain and spinal cord
B.PNS: cranial nerves 12 pairs and spinal nerves 31 pairs
Functional divisions:
A. Autonomic-
B. Somatic-
Functional Divisions of the Nervous System:
A. Autonomic Nervous System (ANS) – Controls involuntary functions such as heart rate, digestion, and respiration. It is further divided into:
• Sympathetic Division (“fight or flight”) – Prepares the body for stress (e.g., increases heart rate, dilates pupils).
• Parasympathetic Division (“rest and digest”) – Promotes relaxation and energy conservation (e.g., slows heart rate, stimulates digestion).
B. Somatic Nervous System (SNS) – Controls voluntary movements by transmitting signals from the brain to skeletal muscles. It also carries sensory information (touch, pain, temperature) from the body to the central nervous system.
The breast itself isn’t an endocrine organ
The two ways of organization of the brain are 1. Organization into forebrain,midbrain and hindbrain
2. Organization into the I.brain stem. ii. cerebrum and cerebellum
What comprises of the forebrain
What comprises of the hind beain
What does the mid brain do
According to the organization of the Brian into brainstem, cerebrum and cerebellum, what does the brainstem comprise of?
Know this functions too wai
Divisions of the Brain and Their Functions
1. Forebrain (Prosencephalon) – Responsible for higher cognitive functions, sensory processing, and autonomic control. It includes:
• 2 pairs of Cerebrum or cerebral hemispheres – Controls thought, memory, voluntary movement, and sensory perception.
• Diencephalon (2 pairs of the Thalamus & 2 pairs of the Hypothalamus on both sides left and right ) – The thalamus relays sensory information, while the hypothalamus regulates hormones, temperature, hunger, and autonomic functions.
2. Midbrain (Mesencephalon) – Acts as a relay center between the forebrain and hindbrain. It controls:
• Reflexes (e.g., visual and auditory reflexes via the superior and inferior colliculi).
• Motor control (via connections with the basal ganglia).
• Regulation of consciousness and sleep (through the reticular formation).
3. Hindbrain (Rhombencephalon) – Controls vital bodily functions and motor coordination. It includes:
• Medulla Oblongata – Regulates breathing, heart rate, and reflexes (coughing, sneezing).
• Pons – Connects different brain regions and aids in motor control and sensory analysis.
• Cerebellum – Coordinates balance, posture, and fine motor movements.
Brain Organization by Structure
• Brainstem (Controls basic life functions and relays information) – Comprises:
• Midbrain
• Pons
• Medulla Oblongata
• Cerebrum – Responsible for higher-order functions like reasoning, memory, and voluntary movement.
• Cerebellum (little cerebrum)– Coordinates movement, balance, and muscle tone.
The brain and spinal cord are found in a space within a bony structure called?
They are surrounddd by protective membranes called meninges (what’s the singular of meninges?)
The spinal cord continues from the medulla oblongata at the base of the skull and terminates at what vertebral level in adults and what in children?
The spinal cord continues with the medulla oblongota, from the skill base and terminates at L2(L2 in adults and L3 in kids) vertebral level in the vertebral canal
The brain and spinal cord are found in a space within a bony structure called the dorsal body cavity (which includes the cranial cavity and vertebral canal).
The singular form of meninges is meninx.
The spinal cord continues from the medulla oblongata at the base of the skull and terminates at the L2 vertebral level in adults and L3 in children, within the vertebral canal.
Yes, the singular of meninges is meninx.
Here are some other words with the ”-nx” to “-nges” pattern:
1. Phalanx → Phalanges (bones of the fingers and toes)
2. Larynx → Larynges (voice box)
3. Sphinx → Sphinges (mythological creatures)
This pattern occurs in certain Greek-derived words in medical and anatomical terminology.
Here are common anatomical terms with their singular and plural forms:
”-nx” → “-nges”
• Phalanx → Phalanges (bones of the fingers and toes)
• Larynx → Larynges (voice box)
”-on” → “-a”
• Ganglion → Ganglia (clusters of nerve cell bodies)
• Mitochondrion → Mitochondria (organelles for energy production)
”-ma” → “-mata”
• Stroma → Stromata (connective tissue framework)
• Sarcoma → Sarcomata (malignant tumors of connective tissue)
”-is” → “-es”
• Epiphysis → Epiphyses (ends of long bones)
• Diaphysis → Diaphyses (shaft of long bones)
”-us” → “-i”
• Bronchus → Bronchi (airways in the lungs)
• Lobus → Lobi (lobes of an organ, e.g., lung or liver)
• Nucleus → Nuclei (cell structures containing DNA)
”-a” → “-ae”
• Vertebra → Vertebrae (bones of the spine)
• Scapula → Scapulae (shoulder blades)
• Fossa → Fossae (depressions or hollows in bones)
These are some of the most commonly used ones in anatomy. Want more?
Here are more anatomical singular and plural forms:
”-nx” → “-nges”
• Meninx → Meninges (protective membranes around the brain and spinal cord)
• Phalanx → Phalanges (bones of the fingers and toes)
• Larynx → Larynges (voice box)
”-on” → “-a”
• Ganglion → Ganglia (clusters of nerve cell bodies)
• Mitochondrion → Mitochondria (organelles for energy production)
• Criterion → Criteria (standards of judgment, used in medical diagnostics)
”-ma” → “-mata”
• Stroma → Stromata (connective tissue framework of organs)
• Sarcoma → Sarcomata (malignant tumors of connective tissue)
• Enema → Enemata (liquid treatments for bowel cleansing)
”-is” → “-es”
• Epiphysis → Epiphyses (ends of long bones)
• Diaphysis → Diaphyses (shaft of long bones)
• Diagnosis → Diagnoses (identifications of diseases)
• Prognosis → Prognoses (predictions of disease outcomes)
”-us” → “-i”
• Bronchus → Bronchi (airways in the lungs)
• Lobus → Lobi (lobes of an organ, e.g., lung or liver)
• Nucleus → Nuclei (cell structures containing DNA)
• Fungus → Fungi (yeast and mold species, some of which cause infections)
”-a” → “-ae”
• Vertebra → Vertebrae (bones of the spine)
• Scapula → Scapulae (shoulder blades)
• Fossa → Fossae (depressions or hollows in bones)
• Pleura → Pleurae (membranes surrounding the lungs)
”-um” → “-a”
• Bacterium → Bacteria (microscopic organisms)
• Ovum → Ova (egg cells)
• Atrium → Atria (upper chambers of the heart)
• Septum → Septa (walls dividing two cavities, e.g., nasal septum)
”-ex” or “-ix” → “-ices”
• Cortex → Cortices (outer layers of organs, e.g., cerebral cortex)
• Appendix → Appendices (part of the digestive system or supplementary material)
• Helix → Helices (spiral structures, e.g., part of the ear)
These are the most common ones in anatomy. Let me know if you want more!
Yes, in anatomical and medical terminology, words ending in ”-nges” usually have a singular form ending in ”-nx.”
For example:
• Phalanges → Phalanx (bones of the fingers and toes)
• Meninges → Meninx (protective membranes around the brain and spinal cord)
• Larynges → Larynx (voice box)
This pattern is consistent for Greek-derived medical terms!s
State the five regions of the spinsl cord
State the number of vertebrae for each plus the spinal nerves for each
State the shape of each vertebrae region
Five Regions of the Spinal Cord and Their Vertebrae, Spinal Nerves, and Shape
1. Cervical Region
• Vertebrae: 7 (C1–C7)
• Spinal Nerves: 8 pairs (C1–C8)
• Vertebral Shape: Small, oval-shaped body with a large vertebral foramen; C3–C6 have bifid spinous processes; C1 (atlas) and C2 (axis) have unique structures.
2. Thoracic Region
• Vertebrae: 12 (T1–T12)
• Spinal Nerves: 12 pairs (T1–T12)
• Vertebral Shape: Heart-shaped body with long, downward-sloping spinous processes; facets for rib articulation.
3. Lumbar Region
• Vertebrae: 5 (L1–L5)
• Spinal Nerves: 5 pairs (L1–L5)
• Vertebral Shape: Large, kidney-shaped body; thick and short spinous processes; designed for weight-bearing.
4. Sacral Region
• Vertebrae: 5 fused (S1–S5)
• Spinal Nerves: 5 pairs (S1–S5)
• Vertebral Shape: Triangular, fused into the sacrum, forming the posterior part of the pelvis.
5. Coccygeal Region
• Vertebrae: 3–5 fused (Co1–Co3/Co5)
• Spinal Nerves: 1 pair called Cnot(Co1)
• Vertebral Shape: Small, triangular, and fused into the coccyx (tailbone).
No, the cervical region has a lordotic curve, which means it is convex anteriorly and concave posteriorly.
To clarify:
• Lordotic curves (Cervical & Lumbar) → Convex anteriorly, Concave posteriorly
• Kyphotic curves (Thoracic & Sacral) → Convex posteriorly, Concave anteriorly
So, cervical is not convex overall, but it is convex when viewed from the front (anteriorly).
Use convex anteriorly and concave posteriorly
Here are the spinal curvatures:
1. Cervical curvature – Lordotic (Convex anteriorly, Concave posteriorly)
2. Thoracic curvature – Kyphotic (Convex posteriorly, Concave anteriorly)
3. Lumbar curvature – Lordotic (Convex anteriorly, Concave posteriorly)
4. Sacral curvature – Kyphotic (Convex posteriorly, Concave anteriorly)
• Lordotic curves: Cervical & Lumbar (Convex anteriorly) • Kyphotic curves: Thoracic & Sacral (Convex posteriorly)
Here are the MCQs without answers:
- Which of the following is the correct singular form of “meninges”?
A) Meninx
B) Meningis
C) Meninga
D) Meningum
- What is the plural form of “phalanx”?
A) Phalanges
B) Phalanxes
C) Phalangi
D) Phalancia
- Which of the following singular-plural pairs is incorrect?
A) Ganglion → Ganglia
B) Larynx → Larynges
C) Cortex → Cortexes
D) Epiphysis → Epiphyses
- The correct singular form of “phalanges” is:
A) Phalango
B) Phalancis
C) Phalanx
D) Phalangum
- Which of the following does NOT follow the “-nx” to “-nges” pluralization rule?
A) Larynx → Larynges
B) Phalanx → Phalanges
C) Meninx → Meninges
D) Bronchus → Bronchi
- Which of these singular-plural pairs is CORRECT?
A) Atrium → Atries
B) Appendix → Appendixes
C) Meninx → Meninges
D) Ovum → Ovums
- The plural form of “larynx” is:
A) Laryngi
B) Larynxes
C) Larynges
D) Laryncia
- Which singular term correctly matches the plural form “ganglia”?
A) Ganglium
B) Ganglion
C) Ganglix
D) Ganglis
- What is the correct plural of “cortex”?
A) Cortexes
B) Cortices
C) Corti
D) Cortae
- Which singular-plural pair is incorrect?
A) Helix → Helices
B) Septum → Septa
C) Bronchus → Bronchae
D) Epiphysis → Epiphyses
Let me know if you need more!
Here are multiple-choice questions (MCQs) based on the singular and plural forms of anatomical terms:
- Which of the following is the correct singular form of “meninges”?
A) Meninx
B) Meningis
C) Meninga
D) Meningum
Answer: A) Meninx
- What is the plural form of “phalanx”?
A) Phalanges
B) Phalanxes
C) Phalangi
D) Phalancia
Answer: A) Phalanges
- Which of the following singular-plural pairs is incorrect?
A) Ganglion → Ganglia
B) Larynx → Larynges
C) Cortex → Cortexes
D) Epiphysis → Epiphyses
Answer: C) Cortex → Cortexes (Correct plural: Cortices)
- The correct singular form of “phalanges” is:
A) Phalango
B) Phalancis
C) Phalanx
D) Phalangum
Answer: C) Phalanx
- Which of the following does NOT follow the “-nx” to “-nges” pluralization rule?
A) Larynx → Larynges
B) Phalanx → Phalanges
C) Meninx → Meninges
D) Bronchus → Bronchi
Answer: D) Bronchus → Bronchi (This follows “-us” to “-i” rule instead)
- Which of these singular-plural pairs is CORRECT?
A) Atrium → Atries
B) Appendix → Appendixes
C) Meninx → Meninges
D) Ovum → Ovums
Answer: C) Meninx → Meninges
- The plural form of “larynx” is:
A) Laryngi
B) Larynxes
C) Larynges
D) Laryncia
Answer: C) Larynges
- Which singular term correctly matches the plural form “ganglia”?
A) Ganglium
B) Ganglion
C) Ganglix
D) Ganglis
Answer: B) Ganglion
- What is the correct plural of “cortex”?
A) Cortexes
B) Cortices
C) Corti
D) Cortae
Answer: B) Cortices
- Which singular-plural pair is incorrect?
A) Helix → Helices
B) Septum → Septa
C) Bronchus → Bronchae
D) Epiphysis → Epiphyses
Answer: C) Bronchus → Bronchae (Correct plural: Bronchi)
Would you like more MCQs?
Explain how the nerves connect with the spinal cord
In summary; Okay so if I understand everything you’re saying, when sensory info comes, it goes to the dorsal root ganglion where the cell bodies of sensory neurons are and then enters the spinal cord through the posterior horn. At the posterior horn, the info is either sent to the anterior horn for quick reflexes or goes to the brain for further processing before it now comes to the anterior horn and enters the ventral root where the dorsal and verntrak root merge to form the spinal nerve and then separates again to form the dorsal and ventral rami.
If the sensory info coming needs autonomic input, it goes to the lateral horn(specifically for sympathetic nervous system innervation and is from the thoracic and upper lumbar regions while parasympathetic is from the brain stem and sacral regions) So if the sensory info needs autonomic response, if the response is simple, it goes to the lateral horn and then to the anterior horn and then to the spinal nerve and then the effector organ right?
If it’s complex, it goes to the brain stem via ascending pathways and to the anterior horn (which contains the parasympathetic neurons of the sacral nerves) via descending pathways and then ventral root and to the spinal nerve and then the effector organ
Complete Overview of Spinal Cord Pathways, Reflex Arcs, and Neuronal Types
- Sensory and Motor Pathways in the Spinal Cord
• Sensory information from the body enters the spinal cord through sensory neurons, whose cell bodies are located in the dorsal root ganglion (DRG).
• This information travels through the dorsal root → posterior horn of the spinal cord, where it can take one of two pathways:- Sent to the brain via ascending tracts for processing (e.g., pain, touch, temperature, proprioception).
- Processed in the spinal cord for an immediate reflex response (bypassing the brain).
• When the brain sends a response, it sends motor signals through descending tracts to the anterior horn, where motor neurons send commands out through the ventral root → spinal nerve → body (muscles or glands).
• The dorsal and ventral roots merge to form a spinal nerve, which then separates again into the dorsal and ventral rami to supply different parts of the body.
- The Role of the Lateral Horn (Autonomic Function)
• The lateral horn is found only in the thoracic and upper lumbar spinal cord regions (T1–L2). It contains autonomic (sympathetic) motor neurons that control involuntary functions like heart rate, digestion, and sweating.
• If the sensory information requires autonomic motor commands, the signal goes from the posterior horn → lateral horn → brain → autonomic response sent back via descending pathways.
• Parasympathetic nervous system neurons do not originate from the lateral horn of the thoracic/lumbar spinal cord. Instead, they come from the brainstem (cranial nerves III, VII, IX, X) and sacral spinal cord (S2–S4). - White Matter Columns (Pathways for Signals)
• The spinal cord has white matter columns that carry sensory (ascending) and motor (descending) information.
• Posterior Columns → Carry sensory signals to the brain (e.g., fine touch, vibration, proprioception).
• Lateral Columns → Carry both sensory (ascending) and motor (descending) signals.
• Anterior Columns → Carry motor commands from the brain to the body. - Reflex Arcs: Fast, Automatic Responses
A reflex arc is an automatic response that bypasses the brain to allow for a faster reaction.
Steps of a Reflex Arc
1. Sensory receptor detects a stimulus (e.g., touching something hot).
2. Sensory neuron (unipolar) carries the signal via dorsal root ganglion → dorsal root → posterior horn.
3. Interneuron (multipolar) in the spinal cord processes the signal (if needed).
4. Motor neuron in the anterior horn gets activated.
5. Motor command exits via the ventral root → spinal nerve → muscle, causing an immediate reaction.
Types of Reflexes
• Monosynaptic Reflex (Simple Reflex):
• Involves only one synapse (no interneurons).
• Example: Stretch reflex (knee-jerk reflex) → Sensory neuron synapses directly onto a motor neuron in the anterior horn, causing the muscle to contract.
• Polysynaptic Reflex (Complex Reflex):
• Involves interneurons and multiple synapses.
• Example: Withdrawal reflex (e.g., pulling away from pain) → Sensory neuron synapses on an interneuron, which then synapses on a motor neuron in the anterior horn.
• Autonomic Reflexes (Lateral Horn Involvement):
• These involve the autonomic nervous system, controlling involuntary functions.
• Example: Bladder control, pupil constriction, heart rate regulation.
• If autonomic motor commands are needed, the signal goes to the lateral horn → brain → autonomic response sent back via descending pathways.
- Types of Neurons in These Pathways
✔ Unipolar neurons → Found in the dorsal root ganglion (sensory neurons), responsible for carrying sensory input to the spinal cord.
✔ Bipolar neurons → Found in special senses (e.g., vision, hearing, smell, taste, balance).
✔ Multipolar neurons → Found in interneurons (posterior horn), motor neurons (anterior horn), and autonomic neurons (lateral horn).
Final Summary
✔ Sensory input enters the spinal cord via the dorsal root → posterior horn.
✔ If autonomic input is required, the signal is sent to the lateral horn for processing before being relayed to the brain.
✔ Motor commands exit via the anterior horn → ventral root → spinal nerve → target muscles or glands.
✔ Reflex arcs allow for immediate responses without brain involvement.
✔ White matter columns organize sensory (ascending) and motor (descending) signals.
✔ Different neurons serve different functions: Unipolar (sensory), bipolar (special senses), multipolar (motor and interneurons).
This version includes all the details while keeping the structure clear. Let me know if anything needs more clarification!
Spinal Cord Structure and Relation to Spinal Nerves
The spinal cord is a cylindrical structure extending from the medulla oblongata to the L1-L2 vertebral level in adults (L3 in children). It serves as the main communication pathway between the brain and the peripheral nervous system (PNS). It is organized into gray matter and white matter, each with distinct functions.
- Cross-Sectional Structure of the Spinal Cord
When viewed in cross-section, the spinal cord consists of gray matter in an H-shape (or butterfly shape) surrounded by white matter.
A. Gray Matter (H-Shaped Region)
• The gray matter is central in the spinal cord and contains neuronal cell bodies, dendrites, and unmyelinated axons.
• It is divided into three horns:
1. Posterior (Dorsal) Horn → Processes sensory (afferent) input from peripheral receptors.
2. Anterior (Ventral) Horn → Contains motor neurons (efferent) that send signals to skeletal muscles.
3. Lateral Horn (only in thoracic & upper lumbar regions) → Contains autonomic neurons that control smooth muscle, cardiac muscle, and glands.
• The central canal runs through the middle of the gray matter and is filled with cerebrospinal fluid (CSF). It is continuous with the fourth ventricle of the brain, allowing CSF circulation.
B. White Matter
• The white matter surrounds the gray matter and consists of myelinated axons that transmit signals between the brain and body.
• It is divided into three columns (funiculi):
1. Anterior (Ventral) Column → Carries descending motor signals.
2. Lateral Column → Contains both ascending sensory & descending motor tracts.
3. Posterior (Dorsal) Column → Carries ascending sensory signals (e.g., touch, proprioception).
These columns contain tracts that allow communication between different levels of the CNS.
- Relationship Between Spinal Cord and Spinal Nerves
The spinal cord gives rise to 31 pairs of spinal nerves, which transmit signals into and out of the CNS.
A. Spinal Nerve Roots
Each spinal nerve is formed by two roots:
1. Dorsal (Posterior) Root
• Carries sensory (afferent) fibers from the body into the spinal cord.
• Contains the dorsal root ganglion (DRG), which houses sensory neuron cell bodies.
• Signals enter the posterior horn of the gray matter for processing.
2. Ventral (Anterior) Root
• Carries motor (efferent) fibers from the spinal cord to muscles and glands.
• Motor neurons originate in the anterior horn and send axons through the ventral root.
3. Formation of Spinal Nerves
• The dorsal and ventral roots merge to form a spinal nerve.
• Since it contains both sensory and motor fibers, a spinal nerve is considered a mixed nerve.
B. Spinal Nerve Branching
After exiting the vertebral column, a spinal nerve splits into two rami:
1. Dorsal Ramus → Innervates deep back muscles, skin of the back.
2. Ventral Ramus → Innervates limbs, anterior & lateral trunk.
• Forms nerve plexuses like the brachial plexus (upper limb) and lumbosacral plexus (lower limb).
- Functional Organization of the Spinal Cord
The spinal cord serves as both a reflex center and a pathway for signals between the brain and the body.
A. Sensory Pathway (Afferent)
• Sensory input (touch, pain, temperature, proprioception) is carried by ascending tracts in the posterior column & lateral column.
• Information reaches the brainstem, thalamus, or cerebrum for processing.
B. Motor Pathway (Efferent)
• Motor commands from the brain travel through descending tracts in the anterior & lateral columns.
• Signals reach motor neurons in the anterior horn, which then send impulses to skeletal muscles.
C. Reflex Arc
• A reflex arc is an automatic, involuntary response to stimuli.
• Sensory neurons detect the stimulus, synapse in the spinal cord, and immediately activate motor neurons, bypassing the brain.
• Example: Knee-jerk reflex (patellar reflex).
- Summary of Key Relationships
Structure Function
Gray Matter Processes sensory & motor signals, houses neuron cell bodies
White Matter Contains ascending & descending tracts for communication
Dorsal Root Carries sensory input (afferent) into the spinal cord
Dorsal Root Ganglion Contains sensory neuron cell bodies
Ventral Root Carries motor output (efferent) from the spinal cord
Spinal Nerve Mixed nerve (contains both sensory & motor fibers)
Dorsal Ramus Innervates back muscles & skin
Ventral Ramus Innervates limbs, anterior & lateral trunk
Central Canal Filled with CSF, continuous with fourth ventricle
Reflex Arc Bypasses the brain, allowing rapid motor response
What about relationship between the cranial nerves , spinal nerves and spinal cord and sympathetic and parasympathetic nerves
Here are the cranial nerves with their actual numbers:
• Cranial Nerve 3 (Oculomotor) → Pupil constriction & lens accommodation.
• Cranial Nerve 7 (Facial) → Controls lacrimal (tear) glands, submandibular & sublingual salivary glands.
• Cranial Nerve 9 (Glossopharyngeal) → Controls the parotid salivary gland.
• Cranial Nerve 10 (Vagus) → Parasympathetic control of the heart, lungs, and digestive organs.
These nerves originate from the brainstem and carry parasympathetic fibers to ganglia before reaching their target organs.
Here’s a structured explanation of the relationship between cranial nerves, spinal nerves, the spinal cord, and the autonomic nervous system (sympathetic and parasympathetic nerves):
- Cranial Nerves and Spinal Nerves
• Cranial Nerves (12 pairs)
• Emerge directly from the brain (mostly from the brainstem).
• Serve the head, neck, and some visceral organs.
• Some are sensory (e.g., optic, olfactory), some motor (e.g., oculomotor, hypoglossal), and some mixed (e.g., vagus, facial).
• Vagus nerve (CN X) plays a major role in the parasympathetic system, regulating heart, lungs, and digestive organs.
• Spinal Nerves (31 pairs)
• Emerge from the spinal cord through intervertebral foramina.
• They are all mixed nerves (carry both sensory and motor fibers).
• Each spinal nerve splits into:
• Dorsal ramus (innervates the back muscles and skin).
• Ventral ramus (innervates limbs and anterior trunk).
• Spinal nerves contribute to sympathetic nervous system via the sympathetic trunk. - Relationship with the Autonomic Nervous System (ANS)
The ANS is divided into:
• Sympathetic Nervous System (“Fight or Flight”)
• Arises from T1-L2 spinal nerves (thoracolumbar origin).
• Travels through sympathetic chain ganglia along the spine.
• Regulates heart rate, blood pressure, bronchodilation, and sweat glands.
• Parasympathetic Nervous System (“Rest and Digest”)
• Arises from cranial nerves (CN III, VII, IX, X) and sacral spinal nerves (S2-S4) → craniosacral origin.
• Regulates digestion, urination, pupil constriction, and slowing of the heart.
• Vagus nerve (CN X) is the most significant parasympathetic nerve, controlling most thoracic and abdominal organs.
- Interaction Between These Systems
• Cranial and spinal nerves supply the body with somatic (voluntary) and autonomic (involuntary) functions.
• The spinal cord acts as a central hub where sensory input enters, is processed, and motor output is sent to target organs.
• The sympathetic system uses spinal nerves to reach organs, while the parasympathetic system uses cranial nerves (mainly vagus) and sacral spinal nerves.
In my notes on how the nerves connect with the spinal cord via the anterior posterior lateral horn, these are the points I have.
Part of the horn deep groove which is a fissure(the anterior median fissure cuz it’s deep)
There was something about the posterior median sulcus and it’s called sulcus cause not it’s deep and there was something about anyeriolaterkal sulcus. I don’t know how these relate
So now there are ventral or anterior rootlets. And the anterior rootlets are in contact with the spinal cord and merge to form anterior roots and carries motor fibers or anterior fibers or motor ventra which are just different names for the same thing I guess.
There are sensory rootlets
The spinal nerves emerge from the intervertebral foramina.
We are to know the parts of the neuron.
The accumulation of cell bodies of the sensory neuron outside the CNs is called ganglion
The accumulation of motor neurons cell bodies which are inside the CNS is called nucleus.
Every spinal nerve has a sensory and motor nerve that is joined together
Mixed nerves have a sensory and motor component
Motor is anterior
Sensory is posterior.
Beyond the spinal nerve, they divide into dorsal and ventral ramus.
Dorsal ramus must go to the back and enter the thoracolumbar fascia which innervates it.
The anterior or ventral ramus takes care of the rest of the body.
Dorsal root is sensory. Ventral root is motor but with both dorsal and anterior ramus, they are both sensory and motor so they’re mixed.
Sympa fibres come from T1-L3 or L2
Parasympa fibres come from or with s2,3,4 nerves plus four cranial nerves.
No cranial nerve is associated with the sympathetic fibers
Sympathetic fibers are thoracolumbar in origin
Para are craniosacral in origin
Sympa and para fibres are motor
I want more in-depth knowledge of everything and how they are all related plus how the anterior lateral and posterior horns come into play
Here’s a detailed breakdown of how everything relates, expanding on your notes while keeping it structured for easy understanding.
- Understanding the Spinal Cord Structure
The spinal cord is divided into gray matter (H-shaped, central) and white matter (outer).
Gray Matter (H-Shaped)
• Divided into three horns:
• Anterior (Ventral) Horn – contains motor neurons (somatic motor function).
• Lateral Horn – contains autonomic (sympathetic and parasympathetic) neurons.
• Posterior (Dorsal) Horn – receives sensory input.
- The Relationship Between Nerves and the Spinal Cord
a) How Spinal Nerves Connect to the Spinal Cord
Spinal nerves arise from the spinal cord through rootlets, which then merge to form roots:
1. Ventral (Anterior) Rootlets → merge to form Ventral (Anterior) Roots
• These carry motor fibers from the spinal cord to muscles and glands.
• The cell bodies of these motor neurons are in the anterior horn of the spinal cord.
• If autonomic fibers (sympathetic or parasympathetic) are present, they originate from the lateral horn.
2. Dorsal (Posterior) Rootlets → merge to form Dorsal (Posterior) Roots
• These carry sensory fibers from the body to the spinal cord.
• The cell bodies of these sensory neurons are located in the dorsal root ganglion (outside the spinal cord).
3. The spinal nerve is formed when the dorsal (sensory) and ventral (motor) roots merge.
• Since it contains both sensory and motor fibers, it is a mixed nerve.
• It emerges from the intervertebral foramen.
4. The spinal nerve splits into:
• Dorsal (Posterior) Ramus → innervates the muscles and skin of the back.
• Ventral (Anterior) Ramus → supplies the rest of the body (limbs, trunk, etc.).
- The Spinal Cord Grooves & Their Importance
The spinal cord has several grooves (sulci and fissures) that help separate different parts:
1. Anterior Median Fissure (Deep groove)
• Located on the anterior side, splits the spinal cord into right and left halves.
• It is deep → called a fissure rather than a sulcus.
• Related to motor output (as motor neurons are in the anterior horn).
2. Posterior Median Sulcus (Shallow groove)
• Located on the posterior (dorsal) side, separating the right and left halves.
• It is not as deep as the anterior median fissure, so it’s called a sulcus.
• Related to sensory input (as sensory neurons are in the posterior horn).
3. Anterolateral Sulcus & Posterolateral Sulcus
• Anterolateral Sulcus → where motor rootlets exit the spinal cord.
• Posterolateral Sulcus → where sensory rootlets enter the spinal cord.
Key Relationship:
• Motor output travels through the anterior root, which exits at the anterolateral sulcus.
• Sensory input enters the posterior root, which enters at the posterolateral sulcus.
- The Autonomic Nervous System & Its Connection to the Spinal Cord
The autonomic nervous system (ANS) is responsible for involuntary control of organs and has two divisions:
1. Sympathetic Nervous System (Thoracolumbar Origin: T1–L2/L3)
• Motor fibers originate from the lateral horn of the spinal cord (T1–L2).
• These fibers exit the spinal cord via the ventral (anterior) root, then synapse in the sympathetic chain ganglia.
• No cranial nerves carry sympathetic fibers.
2. Parasympathetic Nervous System (Craniosacral Origin: CN III, VII, IX, X & S2–S4)
• Cranial portion: Fibers arise from cranial nerves III, VII, IX, X.
• Sacral portion: Fibers originate from S2–S4 (lateral horn of sacral spinal cord).
• These fibers exit via the ventral root, travel through spinal nerves, and reach their target organs.
Key Differences:
• Sympathetic fibers come from the lateral horn of T1–L2 and travel via spinal nerves.
• Parasympathetic fibers come from cranial nerves & sacral spinal nerves (S2–S4).
• Both are motor fibers but affect involuntary functions.
- Summary Table of Key Relationships
Structure Function Related Structures
Anterior (Ventral) Horn Motor output (somatic) Contains cell bodies of motor neurons
Lateral Horn Autonomic motor neurons (sympathetic & parasympathetic) Present in T1–L2 (sympathetic) & S2–S4 (parasympathetic)
Posterior (Dorsal) Horn Sensory input Receives sensory signals from dorsal root
Anterior Rootlets → Anterior Root Carries motor fibers Joins with posterior root to form a mixed spinal nerve
Posterior Rootlets → Posterior Root Carries sensory fibers Contains dorsal root ganglion (sensory neuron cell bodies)
Spinal Nerve Mixed nerve (motor & sensory) Splits into dorsal and ventral rami
Dorsal Ramus Mixed nerve, innervates the back Goes into the thoracolumbar fascia
Ventral Ramus Mixed nerve, innervates limbs & anterior body Takes care of the rest of the body
Sympathetic Fibers (T1–L2/L3) “Fight or flight” Lateral horn → ventral root → sympathetic chain
Parasympathetic Fibers (CN III, VII, IX, X & S2–S4) “Rest and digest” Cranial nerves & sacral spinal nerves
Final Thoughts
• The spinal cord connects sensory and motor fibers through its roots and rami.
• The autonomic nervous system (ANS) operates through the lateral horn for sympathetic (T1–L2) and parasympathetic (S2–S4) control.
• Grooves & sulci help segregate sensory & motor pathways.
• Spinal nerves are mixed nerves, but their roots separate sensory and motor functions before merging.
Let me know if you need further breakdowns!
Mention the functions, names of the cranial nerves
Whether they’re sensory or motor or both or parasympathetic
State the roots of the cranial nerves and their origin for each.
Plus The fissures used to exit the cranial cavity for each nerve
Here’s a detailed and structured breakdown of the cranial nerves, including functions, sensory/motor classification, parasympathetic components, roots, origins, and exit foramina.
Cranial Nerves Overview
The 12 pairs of cranial nerves (CN I–XII) arise from the brainstem (except CN I & II) and exit the cranial cavity through specific foramina.
Cranial Nerve Name Function Type Root Origin Brain Origin Exit Foramen
CN I Olfactory Smell Sensory Olfactory epithelium Telencephalon (Olfactory bulb) Cribriform plate (ethmoid bone)
CN II Optic Vision Sensory Retina Diencephalon (Optic chiasm) Optic canal
CN III Oculomotor Eye movement (SR, IR, MR, IO), pupil constriction (PS), accommodation Motor + Parasympathetic Midbrain (anterior) Midbrain Superior orbital fissure
CN IV Trochlear Eye movement (SO muscle) Motor Midbrain (posterior) Midbrain Superior orbital fissure
CN V1 Ophthalmic (Trigeminal branch) Sensation to forehead, cornea Sensory Pons Pons Superior orbital fissure
CN V2 Maxillary (Trigeminal branch) Sensation to cheeks, upper teeth Sensory Pons Pons Foramen rotundum
CN V3 Mandibular (Trigeminal branch) Sensation to jaw, lower teeth; motor to mastication muscles Both (Sensory + Motor) Pons Pons Foramen ovale
CN VI Abducens Eye movement (LR muscle) Motor Pons (medial) Pons Superior orbital fissure
CN VII Facial Facial expression, taste (anterior 2/3 tongue), saliva/tear secretion (PS) Both (Motor + Sensory + Parasympathetic) Pons Pons Internal acoustic meatus → Stylomastoid foramen
CN VIII Vestibulocochlear Hearing & balance Sensory Inner ear Pons & Medulla Internal acoustic meatus
CN IX Glossopharyngeal Taste (posterior 1/3 tongue), swallowing, saliva secretion (PS) Both (Motor + Sensory + Parasympathetic) Medulla Medulla Jugular foramen
CN X Vagus Autonomic control of heart, lungs, digestion; taste, swallowing Both (Motor + Sensory + Parasympathetic) Medulla Medulla Jugular foramen
CN XI Accessory Motor to SCM & trapezius muscles Motor Medulla & Spinal cord (C1–C5) Medulla Jugular foramen
CN XII Hypoglossal Tongue movement Motor Medulla Medulla Hypoglossal canal
Key Notes on Cranial Nerve Functions
1. Pure Sensory Nerves: CN I, II, VIII
2. Pure Motor Nerves: CN III, IV, VI, XI, XII
3. Mixed (Sensory + Motor) Nerves: CN V, VII, IX, X
4. Cranial Nerves with Parasympathetic Fibers: CN III, VII, IX, X
Cranial Nerves with Parasympathetic Function
• CN III (Oculomotor): Pupillary constriction, lens accommodation (Edinger-Westphal nucleus).
• CN VII (Facial): Lacrimal & salivary gland secretion (submandibular & sublingual glands).
• CN IX (Glossopharyngeal): Parotid gland secretion.
• CN X (Vagus): Heart rate, digestion, respiratory control.
Summary Table of Cranial Nerve Exits
Cranial Nerve | Exit Foramen
CN I (Olfactory) | Cribriform plate
CN II (Optic) | Optic canal
CN III (Oculomotor) | Superior orbital fissure
CN IV (Trochlear) | Superior orbital fissure
CN V1 (Ophthalmic) Superior orbital fissure
CN V2 (Maxillary) Foramen rotundum
CN V3 (Mandibular) Foramen ovale
CN VI (Abducens) Superior orbital fissure
CN VII (Facial) Internal acoustic meatus → Stylomastoid foramen
CN VIII (Vestibulocochlear) Internal acoustic meatus
CN IX (Glossopharyngeal) Jugular foramen
CN X (Vagus) Jugular foramen
CN XI (Accessory) Jugular foramen
CN XII (Hypoglossal) Hypoglossal canal
Let me know if you need further explanations!
Here are some mnemonic devices to help you remember the cranial nerves, their functions, and their exit foramina:
- Cranial Nerves (CN I–XII)
Mnemonic (first letters of each nerve):
Oh Oh Oh To Touch And Feel Very Green Vegetables AH
Breakdown:
1. Olfactory (CN I)
2. Optic (CN II)
3. Oculomotor (CN III)
4. Trochlear (CN IV)
5. Trigeminal (CN V)
6. Abducens (CN VI)
7. Facial (CN VII)
8. Vestibulocochlear (CN VIII)
9. Glossopharyngeal (CN IX)
10. Vagus (CN X)
11. Accessory (CN XI)
12. Hypoglossal (CN XII)
- Cranial Nerve Functions (Sensory, Motor, Both)
Mnemonic:
Some Say Marry Money But My Brother Says Big Brains Matter Most
Breakdown:
1. Sensory (CN I)
2. Sensory (CN II)
3. Motor (CN III)
4. Motor (CN IV)
5. Both (CN V)
6. Motor (CN VI)
7. Both (CN VII)
8. Sensory (CN VIII)
9. Both (CN IX)
10. Both (CN X)
11. Motor (CN XI)
12. Motor (CN XII)
- Cranial Nerve Exit Foramina
Mnemonic (Foramina in order of nerve exit):
Cleaners Only Spray Smelly Rats On Some Internal Injured Jugular Jugular Homes
Breakdown:
1. Cribriform plate (CN I – Olfactory)
2. Optic canal (CN II – Optic)
3. Superior orbital fissure (CN III, IV, V1, VI – Oculomotor, Trochlear, Ophthalmic, Abducens)
4. Foramen Rotundum (CN V2 – Maxillary)
5. Foramen Ovale (CN V3 – Mandibular)
6. Superior orbital fissure (CN VI – Abducens)
7. Internal acoustic meatus (CN VII, VIII – Facial, Vestibulocochlear)
8. Jugular foramen (CN IX, X, XI – Glossopharyngeal, Vagus, Accessory)
9. Hypoglossal canal (CN XII – Hypoglossal)
- Parasympathetic Cranial Nerves (III, VII, IX, X)
Mnemonic:
3, 7, 9, 10 → “1973” → Think of a random event in 1973
Breakdown:
• CN III (Oculomotor): Pupil constriction, lens accommodation
• CN VII (Facial): Lacrimal, submandibular, sublingual glands
• CN IX (Glossopharyngeal): Parotid gland
• CN X (Vagus): Heart, lungs, digestion
Would you like more memory tricks for anything else?
Cranial nerves do not carry sympathetic fibers because the sympathetic nervous system originates from the thoracic and lumbar spinal cord (T1–L2), not the brainstem. No, only cranial nerves III–XII originate from the brainstem.
Difference Between Cranial & Spinal Nerves:
1. Cranial Nerves (CN I–XII)
• Originate from the brain (not the spinal cord).
• CN I (Olfactory) and CN II (Optic) do NOT come from the brainstem—they arise from the cerebrum and diencephalon, respectively.
• CN III–XII come from the brainstem (midbrain, pons, medulla).
2. Spinal Nerves (31 Pairs)
• Originate from the spinal cord, not the brainstem.
• They exit through the intervertebral foramina and control body functions below the head and neck.
So, cranial nerves come from the brain (including the brainstem), while spinal nerves come from the spinal cord.
How Does the Head Get Sympathetic Innervation?
• Sympathetic fibers originate from T1–L2 in the lateral horn of the spinal cord.
• They travel upward through the sympathetic chain to synapse in the superior cervical ganglion.
• From there, postganglionic sympathetic fibers hitchhike on blood vessels (like the internal carotid artery) to reach the head and face.
So, instead of cranial nerves carrying sympathetic fibers, the sympathetic nerves travel along arteries and other pathways to reach their target organs.
Overview of Spinal Nerves and Their Connection to the Spinal Cord
1. Spinal Nerve Structure
• 31 pairs of spinal nerves
• Each spinal nerve emerges from the spinal cord through the intervertebral foramina
• Composed of sensory (afferent) and motor (efferent) fibers, making them mixed nerves
2. Roots and Horns
• Dorsal (posterior) root → carries sensory signals into the spinal cord
• Dorsal root ganglion → contains sensory neuron cell bodies
• Ventral (anterior) root → carries motor signals out of the spinal cord
• Gray matter (H-shaped):
• Posterior horn → sensory processing
• Anterior horn → motor neuron cell bodies
• Lateral horn → autonomic motor neurons (T1–L2 for sympathetic)
3. Spinal Nerve Divisions
• After exiting the spinal cord, spinal nerves divide into:
• Dorsal ramus → innervates back muscles and skin
• Ventral ramus → innervates limbs and anterior body
4. Autonomic Connections
• Sympathetic fibers (T1–L2) exit via the lateral horn
• Parasympathetic fibers (S2–S4) exit via the ventral root
• No cranial nerves carry sympathetic fibers; only parasympathetic ones (CN III, VII, IX, X)
Would you like a more detailed explanation of any part?
Let’s break it down step by step so you can clearly picture how the roots and horns of the spinal cord relate to each other.
- Understanding the Gray Matter (Horns)
The spinal cord’s gray matter is H-shaped and has three horns:
• Posterior (dorsal) horn → Receives sensory input
• Anterior (ventral) horn → Sends out motor signals
• Lateral horn (T1–L2) → Autonomic motor neurons (sympathetic)
- How Spinal Nerves Connect to the Spinal Cord
Each spinal nerve is formed by two roots:
• Dorsal root (sensory fibers): Carries information into the spinal cord
• Enters through the posterior horn
• Has a dorsal root ganglion (contains sensory neuron cell bodies)
• Ventral root (motor fibers): Carries signals out of the spinal cord
• Originates from motor neurons in the anterior horn
• No ganglion because motor neuron cell bodies are inside the spinal cord
Key relationship:
• Sensory nerves (afferent) → enter through the dorsal root → synapse in the posterior horn
• Motor nerves (efferent) → originate in the anterior horn → exit through the ventral root
- Path of Nerve Impulses
• Touching a hot object:- Sensory fibers in the skin detect heat → signal travels through the dorsal root into the posterior horn
- The signal is processed in the spinal cord and a reflex response is generated
- Motor neurons in the anterior horn send an impulse out through the ventral root to move your hand away
- What Happens After the Roots Join?
• The dorsal and ventral roots merge to form a spinal nerve (which is mixed: both sensory & motor)
• Then, the spinal nerve splits into:
• Dorsal ramus (innervates back muscles & skin)
• Ventral ramus (innervates front of the body & limbs) - Where Does the Lateral Horn Come In?
• Found only in T1–L2 because it contains sympathetic autonomic neurons
• These sympathetic fibers exit via the ventral root and go to the sympathetic ganglia
Final Summary (Easy to Picture)
• Dorsal root → Posterior horn (sensory input, ganglion present)
• Ventral root → Anterior horn (motor output, no ganglion)
• Lateral horn (T1–L2) → Sympathetic autonomic motor fibers exit via ventral root
• Roots join to form spinal nerves → split into dorsal & ventral rami
Would you like a diagram to visualize this better?
DRAW a thoracic spinal cord segment with its segmental (intercostal) nerve to show the following:
Anterior and posterior roots
Anterior and posterior primary rami
Posterior root (sensory) ganglion
Cutaneous branches
Routes of sensory and motor fibres
How xo I do this
To draw a thoracic spinal cord segment with its intercostal nerve and the listed structures, follow these steps:
Step-by-Step Guide to Drawing:
- Outline the Spinal Cord Segment
• Draw an oval or cylindrical shape to represent the spinal cord.
• Label the anterior (ventral) side and the posterior (dorsal) side clearly. - Draw the Spinal Nerve Roots
• Draw anterior (ventral) roots extending from the anterior side of the spinal cord.
• These carry motor fibers from the anterior horn.
• Draw posterior (dorsal) roots extending from the posterior side.
• These carry sensory fibers from the posterior horn.
• Label them accordingly. - Add the Posterior Root Ganglion
• On the posterior root, draw a bulge (oval-shaped) to represent the posterior root ganglion (where sensory neuron cell bodies are located). - Form the Spinal Nerve
• Show where the anterior and posterior roots merge to form a short mixed spinal nerve (containing both motor and sensory fibers). - Draw the Primary Rami
• From the spinal nerve, draw two branches:
• Anterior (ventral) primary ramus → Extends forward to supply the muscles and skin of the anterior/lateral body wall and limbs.
• Posterior (dorsal) primary ramus → Extends backward to innervate the deep back muscles and skin of the back. - Show the Intercostal Nerve and Cutaneous Branches
• In the thoracic region, the anterior ramus becomes an intercostal nerve, running between the ribs.
• Draw small branches from the intercostal nerve:
• Lateral cutaneous branch → Pierces through the muscles to supply the skin of the lateral thorax.
• Anterior cutaneous branch → Innervates the skin near the midline of the chest. - Indicate the Routes of Sensory and Motor Fibers
• Use arrows:
• Sensory fibers (from the skin and muscles) travel via the posterior root into the spinal cord.
• Motor fibers (from the spinal cord) exit via the anterior root to innervate muscles.
Final Touches
• Label each structure clearly.
• Ensure the spinal cord, roots, rami, ganglion, and cutaneous branches are distinguishable.
What is cauda equina?
What level of the vertebrae does the spinal cord end at?
What is the name of that place rjay the spinal cord ends at
What lumbar is lumbar puncture done at?
Question 1:
Which of the following statements is correct regarding spinal nerve exits?
A) The L2 spinal nerve exits above the L2 vertebra.
B) The L2 spinal nerve exits below the L2 vertebra.
C) All spinal nerves exit above their corresponding vertebrae.
D) The L2 spinal nerve exits at the same level as the conus medullaris.
Question 2:
Where does the C6 spinal nerve exit?
A) Above the C6 vertebra
B) Below the C6 vertebra
C) Between the C6 and C7 vertebrae
D) Below the C7 vertebra
The cauda equina is a bundle of nerve roots that descend from the end of the spinal cord (around L1-L2) and extend down through the lower back. It looks like a horse’s tail, which is how it got its name. These nerves control movement and sensation in the legs, bladder, and bowels.
The conus medullaris is the terminal end of the spinal cord, located around L1–L2 in adults.
Key Features:
• The spinal cord does not extend the full length of the vertebral column—it ends at the conus medullaris.
• Below it, the cauda equina (a bundle of spinal nerve roots) continues down to exit at their respective levels.
• The filum terminale, a fibrous strand, extends from the conus medullaris to anchor the spinal cord to the coccyx.
This structure is clinically important because spinal taps (lumbar punctures) are performed below L2 to avoid damaging the spinal cord.
Lumbar Puncture (LP) – It is typically performed between L3-L4 or L4-L5, because the spinal cord ends higher (around L1-L2), reducing the risk of injury.
2. End of the Spinal Cord – The spinal cord ends at the conus medullaris, which is usually at L1-L2 in adults.
Not exactly! Here’s how it works:
• In the cervical spine (C1-C7), nerves exit above their corresponding vertebrae. For example, the C2 nerve exits above the C2 vertebra.
• From T1 downward, nerves exit below their corresponding vertebrae. So, the L2 spinal nerve exits below the L2 vertebra, not above it.
Example:
• The L1 nerve exits below the L1 vertebra.
• The L2 nerve exits below the L2 vertebra.
• The L3 nerve exits below the L3 vertebra, and so on.
Yes, exactly! The spinal cord itself ends at the L1-L2 vertebral level (not the L1,L2 nerve level), forming the conus medullaris.
However, the spinal nerves (like L2, L3, etc.) continue downward as the cauda equina and exit below their corresponding vertebrae.
So:
• The L2 vertebra is a bone.
• The L2 spinal nerve exits below the L2 vertebra.
• The spinal cord stops around L1-L2, but the nerve roots continue down.
That’s why a lumbar puncture is done at L3-L4 or L4-L5—to avoid damaging the spinal cord!
Does this make sense now?
Here are two MCQs based on spinal nerve exit points:
Question 1:
Which of the following statements is correct regarding spinal nerve exits?
A) The L2 spinal nerve exits above the L2 vertebra.
B) The L2 spinal nerve exits below the L2 vertebra.
C) All spinal nerves exit above their corresponding vertebrae.
D) The L2 spinal nerve exits at the same level as the conus medullaris.
Answer: B) The L2 spinal nerve exits below the L2 vertebra.
• Explanation: In the cervical region (C1-C7), nerves exit above their corresponding vertebrae. However, from T1 downward, spinal nerves exit below their corresponding vertebrae. Therefore, the L2 nerve exits below the L2 vertebra.
Question 2:
Where does the C6 spinal nerve exit?
A) Above the C6 vertebra
B) Below the C6 vertebra
C) Between the C6 and C7 vertebrae
D) Below the C7 vertebra
Answer: A) Above the C6 vertebra
• Explanation: In the cervical spine (C1-C7), spinal nerves exit above their corresponding vertebrae. The C6 nerve exits above the C6 vertebra, between C5 and C6. However, starting from T1 downward, nerves exit below their respective vertebrae.
Briefly explain the difference between the rami and roots of the spinal nerves
The roots and rami of spinal nerves differ in their function and location:
• Spinal Roots (Dorsal & Ventral Roots): These are closer to the spinal cord and only carry one type of nerve fiber:
• Dorsal root → Sensory (afferent) fibers
• Ventral root → Motor (efferent) fibers
• Spinal Rami (Dorsal & Ventral Rami): These are branches of the spinal nerve after the roots merge, and they carry both sensory and motor fibers:
• Dorsal ramus → Supplies muscles and skin of the back
• Ventral ramus → Supplies the limbs and anterior body
So, roots are separate (sensory or motor), while rami are mixed (both sensory and motor).
14.All the following are components of the cell theory except …
A.All organisms are composed of cells and its products.
B.Cell is the smallest structural unit of life.
C.Structure and function of organisms are due to functions of the cell.*
Cells come from preexisting cells.
What is the cell theory?
Answer is C
Cell theory – what are its components?
1. All living things are made of cells and their products.
2. Cells are the basic structural and functional units of life.
3. All cells arise from pre-existing cells.
The incorrect option was C: “Structure and function of organisms are due to functions of the cell” — this is a logical consequence of the theory, not one of the original statements.
35.Clearing is used in tissue processing to …
A.remove alcohol which is immiscible with toluene and xylene.
B.remove alcohol which is miscible with paraffin.
C.remove alcohol which is immiscible with paraffin.
remove alcohol which might contain some water.
Clearing is used in tissue processing to …
→ Correct answer: C. remove alcohol which is immiscible with paraffin.
Explanation:
• Clearing is done after dehydration (with alcohol) and before embedding (with paraffin wax).
• Since alcohol does not mix with paraffin, a clearing agent (like xylene or toluene) is used to remove the alcohol and allow paraffin to infiltrate the tissue.
Other options:
• A & B: Misstatements — xylene/toluene are miscible with paraffin, not with alcohol.
• D. remove alcohol which might contain some water → Water is already removed during dehydration.
You’re absolutely right to think critically about this — let’s clarify it in a simple and accurate way.
Clearing in Tissue Processing – What’s Really Happening:
1. Dehydration step: You first remove water from the tissue using alcohol (usually ethanol).
2. Clearing step: Alcohol is then removed and replaced with a substance (clearing agent) that is:
• miscible with alcohol, and also miscible with paraffin wax.
So actually:
• Xylene is miscible with alcohol AND with paraffin, and that’s why xylene is used in the clearing step — it acts as a bridge between the alcohol and paraffin wax.
So the correct explanation is:
Clearing is used to remove alcohol (which is not miscible with paraffin), and replace it with xylene (which is miscible with both alcohol and paraffin).
Therefore, the correct answer is:
C. remove alcohol which is immiscible with paraffin.
Your original understanding was correct — alcohol and paraffin don’t mix, so you need to get rid of alcohol first by using xylene. Xylene allows the tissue to be ready for infiltration with paraffin wax.
Let me know if you’d like a simple diagram or analogy for this process!
32) What is the connection between the first rib and the sternum?
A. Fibrocartilage joint
B. Synovial joint
C. Primary cartilaginous joint (synchondrosis)
D. Secondary cartilaginous joint (symphysis)
MCQ:
32) What is the connection between the first rib and the sternum?
A. Fibrocartilage joint
B. Synovial joint
C. Primary cartilaginous joint (synchondrosis)
D. Secondary cartilaginous joint (symphysis)
Answer: C. Primary cartilaginous joint (synchondrosis)
Explanation:
The first rib connects to the manubrium of the sternum via a primary cartilaginous joint, also called a synchondrosis, which is immovable and made of hyaline cartilage. This is in contrast to the second to seventh ribs, which form synovial joints with the sternum.
Examples of Synchondrosis and Syndesmosis Joints
- Synchondrosis (Cartilaginous Joint - Primary Cartilaginous)
• These are bones joined by hyaline cartilage and are usually temporary (they ossify with age).
• Examples:
• Epiphyseal plates (growth plates in long bones, which ossify after growth).
• First sternocostal joint (between the first rib and sternum).
• Spheno-occipital synchondrosis (at the base of the skull, fuses in adulthood). - Syndesmosis (Fibrous Joint)
• These are bones connected by a ligament or interosseous membrane, allowing limited movement.
• Examples:
• Distal tibiofibular joint (between tibia & fibula).
• Interosseous membrane between the radius and ulna (allows slight movement in pronation/supination).
So, synchondrosis is cartilage-based, while syndesmosis is ligament-based.
A 19-year-old college student came to doctor’s office for a neurological exam. Physician tells him synapses are absent from which of the following structures?
A. Anterior horn of spinal cord
B. Dorsal root ganglia
C. Sympathetic chain ganglia
D. Dendrites
A 19-year-old student came for a neurological exam. Synapses are absent from which of the following structures?
Answer: B. Dorsal root ganglia
• No synapses occur in dorsal root ganglia; they contain cell bodies of sensory neurons, not synaptic junctions.
The dorsal root ganglia function as relay stations housing the cell bodies of sensory neurons, but they do not contain synapses. The actual synaptic transmission of sensory information occurs within the spinal cord, not in the DRG.
In the context of the neurological examination question, the correct answer is B. Dorsal root ganglia. This is because synapses are absent in the dorsal root ganglia (DRG).
Explanation:
• Dorsal Root Ganglia (DRG): The DRG contains the cell bodies of pseudounipolar sensory neurons. These neurons have a unique structure where a single process bifurcates into two branches:
• Peripheral Branch: Extends to sensory receptors in the body, collecting sensory information.
• Central Branch: Carries this sensory information into the spinal cord.
Importantly, no synapses occur within the DRG. The sensory information is transmitted directly from the peripheral branch, through the cell body in the DRG, and along the central branch into the spinal cord, where it then synapses with other neurons.
In contrast:
• A. Anterior Horn of the Spinal Cord: This region contains the cell bodies of motor neurons. Synapses occur here between interneurons and motor neurons, facilitating motor responses.
• C. Sympathetic Chain Ganglia: These ganglia are part of the autonomic nervous system and contain synapses between preganglionic and postganglionic sympathetic neurons.
• D. Dendrites: Dendrites are structures of neurons that receive synaptic inputs from other neurons. Synapses occur on dendrites but not within them as standalone structures.
Therefore, among the options provided, synapses are absent in the dorsal root ganglia.
40yr old female patient with blood pressure was examined at the emergency department, her physician found blood from a blood vessel which carries richly oxygenated blood. Which of the following vessels was affected
A. Superior vena cava
B. Pulmonary arteries
C. Pulmonary veins
D. Portal vein
Microvilli and cilia are similar because
A. They’re both strengthened by microfilament
B. Both hv 9+2 arrangements of microfilament
C Both are extensions of the cytoplasm
D same length or size
- In ethics ……… stands for excellence or virtue
A. Sophia
B. Arete
C. Eudamonia
D. Phronesis
The seven main causes of human actions are attributed to…
A. Aristotle
B. Descartes
C. Socrates
D. Plato
Q4: In ethics, _____ stands for excellence or virtue
Correct answer: B. Arete
Other options explained:
• A. Sophia – Refers to wisdom in Greek philosophy, not virtue.
• C. Eudaimonia – Means human flourishing or happiness, often the goal or outcome of living with Arete (virtue), not the virtue itself.
• D. Phronesis – Refers to practical wisdom (knowing how to act rightly), not virtue in itself but a quality of good ethical judgment.
So, Arete = moral excellence, while Eudaimonia = goal, Sophia = intellectual wisdom, and Phronesis = practical wisdom.
Q10: Synapses are absent from which of the following?
Correct answer: B. Dorsal root ganglia
Other options explained:
• A. Anterior horn of spinal cord – Contains motor neuron cell bodies, and synapses occur here between interneurons and motor neurons.
• C. Sympathetic chain ganglia – These are autonomic ganglia, and synapses definitely occur here between preganglionic and postganglionic neurons.
• D. Dendrites – Synapses occur on dendrites, as they receive input from other neurons.
→ Dorsal root ganglia contain only cell bodies of sensory neurons, and the signal passes without synapsing there.
Microvilli and cilia are similar because:
Answer: C. Both are extensions of the cytoplasm
• Microvilli increase surface area for absorption (supported by actin/microfilaments).
• Cilia aid in movement (supported by microtubules, not microfilaments).
Q12: Bleeding from a vessel carrying oxygen-rich blood — which vessel is it?
Correct answer: C. Pulmonary veins
Other options explained:
• A. Superior vena cava – A vein that carries deoxygenated blood from the upper body to the heart.
• B. Pulmonary arteries – Although they are arteries, they carry deoxygenated blood from the heart to the lungs (they’re exceptions to the general artery-vein oxygen rule).
• D. Portal vein – Carries nutrient-rich, deoxygenated blood from intestines to the liver.
→ The only vein that carries oxygenated blood is the pulmonary vein (from lungs to heart).
Correct answer: A. Aristotle
Explanation:
Aristotle, in his work “Nicomachean Ethics”, identified seven causes or reasons why people take action, which are:
1. Chance
2. Nature
3. Compulsion
4. Habit
5. Reason
6. Passion (emotion)
7. Desire
These help explain why humans behave the way they do, from logical reasoning to emotional impulses or even external forces.
Other options explained:
• B. Descartes – Known for rationalism and the quote “I think, therefore I am”, not this classification of human actions.
• C. Socrates – Focused more on ethics and self-knowledge, but did not list these seven causes.
• D. Plato – A student of Socrates who contributed to moral philosophy, but Aristotle (his student) made this specific classification.
Would you like a quick mnemonic to remember the seven causes?
1 Which of the following is not a characteristic of image formed in front of the principal forcus of the first objective lens.
A.Magnified
B. Inverted
C.Erect
D. Real
- The following are negative feedback mechanisms except
A. Water regulation
B. Thyroxine production
C. Blood clotting
D. BP regulation - What is the plural form of meniscus?
Menisci
Meniscuses
Meniscuss
Meniscea
4 Who is the father of physiology?
A. Claude Benard
B. Canon
5.The current system of anatomical terminology is based on
A. Greek and Latin
B. Terminogia anatomica
C. Nomina anatomical
D. Eponyms
Here are the answers with brief explanations:
- Which of the following is not a characteristic of the image formed in front of the principal focus of the first objective lens?
✔ C. Erect
• Explanation: In a compound microscope, the first image formed by the objective lens (in front of the principal focus) is:
• Magnified
• Inverted
• Real
• So, it is not erect — the image is inverted. - The following are negative feedback mechanisms except
✔ C. Blood clotting
• Explanation:
• Negative feedback works to reverse a change (e.g., water regulation, BP regulation, thyroxine regulation).
• Blood clotting is positive feedback, because once a clot starts, it promotes more clotting until the wound is sealed. - What is the plural form of meniscus?
✔ A. Menisci
• Explanation: “Meniscus” is Latin in origin. The correct plural is menisci. - Who is the father of physiology?
✔ A. Claude Bernard
• Explanation: Claude Bernard is considered the father of modern physiology. He introduced the concept of “milieu intérieur” (internal environment), foundational for understanding homeostasis. - The current system of anatomical terminology is based on:
✔ B. Terminologia Anatomica
• Explanation: Terminologia Anatomica is the modern, standardized international system for naming anatomical structures, replacing Nomina Anatomica and eliminating eponyms (terms based on people’s names).
Image Formation in a Microscope
A compound microscope uses two convex lenses to magnify an object:
1. Objective lens (close to the specimen)
2. Eyepiece lens (close to the eye)
Each lens plays a specific role in image formation.
Step 1: The Role of the Objective Lens
• The objective lens collects light from the specimen and creates an inverted, real, and magnified image.
• This only happens because the specimen is placed just beyond the focal point (F) of the objective lens.
• The real image is then formed inside the microscope tube, closer to the eyepiece lens.
Step 2: The Role of the Eyepiece Lens
• The eyepiece lens takes the real image from the objective lens and acts like a magnifying glass, creating a magnified, virtual, and erect final image that the observer sees.
• This happens because the real image from the objective lens is placed inside the focal length of the eyepiece.
Now, Relating This to Your Question:
1. If the object (specimen) is closer than F of the objective lens:
• The objective lens will form a virtual image, which cannot be used by the eyepiece lens properly.
• This setup is NOT how a microscope works.
2. If the object is beyond F of the objective lens (correct placement):
• The objective lens forms a real, inverted, magnified image.
• The eyepiece lens further magnifies it and makes it virtual and erect (as seen by the observer).
Final Answer to Your Question:
• If an object is placed far from F of the objective lens (but still close enough for magnification), the image is inverted and real.
• If the object is too close to the objective lens (before F), the image is virtual and cannot be used correctly by the microscope.
Would you like me to break this down further with a diagram?
Okay! Imagine you have a magnifying glass. If you hold it far from a book, the letters might look upside down and big—this is a real image because the light actually comes together to form the image.
Now, if you bring the magnifying glass very close to your eye and look at a small ant, the ant looks bigger but still upright—this is a virtual image because the light doesn’t actually come together but only looks like it does.
A microscope works like this:
1. The first lens (objective lens) makes a real, upside-down, and bigger image of the tiny object.
2. The second lens (eyepiece lens) acts like the magnifying glass you hold close to your eye. It makes the image even bigger but keeps it virtual and upright so your eyes can see it clearly.
The reason the final image is virtual is that your eyes can’t focus on real images formed deep inside the microscope, so the eyepiece makes it seem as if the image is floating in front of you at a comfortable distance.
Does that make more sense?
