Open PPQ

Question 1

Feature of femoral ring

Answer 1

The femoral ring is an opening of the femoral canal which is located deep to the inguinal ligament.
Medial border-Lacunar ligament
Lateral-femoral vein in the intermediate compartment of the femoral sheet
Anterior-Inguinal ligament
Posterior-Pectineal ligament overlying the pectineus muscle and its fascia covering the superior pubic ramus
Crucial site for hernia.

Question 2

Describe the inner surface of the right ventricle

Answer 2

1-Trabeculae carneae: Inner surface of the right ventricle is lined with irregular muscular ridges known as trabeculae carneae. These spongy structures prevents stagnation of blood.
2-Papillary muscles: Cone-shaped projections from the inner surface of the right ventricle. They anchor the chordae tendineae which are fibrous cords connected to the tricuspid valve. The contraction of the papillary muscles prevents the valve from prolapsing into the right atrium during ventricular systole.
3-Moderator band(Septomarginal Trabecula): Muscular structure that traverses the right ventricular cavity. It contains a portion of the right bundle branch of the conducting system. The moderator band helps coordinate the contraction of different parts of the right ventricle and contributes efficient ventricular ejection.
4-(!)Crista Supraventricularis: muscular ridge that runs along the upper part of the right ventricular cavity. It separates the infundibulum from the trabeculated portion of the right ventricle. Separation of pulmonary valve from the tricuspid valve that is why the inlet and outlet are separated distantly.
5-Infundibulum: Smooth walled conical region leads to the pulmonary trunk. Efficient ejection of blood into the pulmonary circulation.
6-Chordae tendineae- fibrous collagenous structures that supports the leaflets of the AV valves.

Question 3

Describe lesser omentum

Answer 3

The lesser omentum is a double-layered fold of peritoneum, a serous membrane that lines the abdominal cavity. It has two main components:

1. Hepatogastric Ligament:
   
   • The hepatogastric ligament is the portion of the lesser omentum that extends between the liver and the lesser curvature of the stomach. It attaches to the lesser curvature of the stomach and then spreads out to attach to the visceral surface of the liver. This ligament helps support and stabilize the stomach relative to the liver.
2. Hepatoduodenal Ligament:
   
   • The hepatoduodenal ligament runs from the liver to the first part of the duodenum. It contains the portal triad, which includes the portal vein, common bile duct, and proper hepatic artery. The hepatoduodenal ligament helps connect the liver and duodenum and carries important structures involved in the transport of blood and bile.

These two components enclose the lesser sac (omental bursa) posteriorly, providing a protective covering for this region of the abdominal cavity.

Functions of the Lesser Omentum:
- Support for Stomach and Liver: The lesser omentum helps provide support and stabilization for the stomach and liver.
- Containment of Structures: It contains and protects important vascular and biliary structures within the hepatoduodenal ligament.
- Boundary of the Lesser Sac: The lesser omentum forms part of the boundary of the lesser sac (omental bursa), which is a potential space in the abdominal cavity.

The lesser omentum is anatomically distinct from the greater omentum, which is a larger, apron-like fold of peritoneum that hangs down from the greater curvature of the stomach and drapes over the abdominal organs.

Question 4

Describe the relationship between bladder and terminal parts of the ureters

Answer 4

The relationship between the bladder and the terminal parts of the ureters involves the entry of the ureters into the bladder and the prevention of backflow of urine. Here’s a brief description:

1. Ureteral Orifices:
   
   • The terminal parts of the ureters enter the bladder at specific points known as ureteral orifices. These orifices are located in the trigone region of the bladder.
2. Trigone of the Bladder:
   
   • The trigone is a triangular-shaped area in the bladder formed by the ureteral orifices and the internal urethral orifice. It is a smooth-surfaced region, and the ureteral orifices mark its posterior angles.
3. Ureterovesical Junction (UVJ):
   
   • The point where the ureter enters the bladder is called the ureterovesical junction (UVJ). At the UVJ, there are valves formed by the mucosa and submucosa that act as one-way flaps, preventing the backflow of urine from the bladder into the ureters. This mechanism is crucial for maintaining urinary continence and preventing reflux of urine.
4. Ureteral Peristalsis:
   
   • Peristaltic contractions of the ureters, especially during micturition (urination), help propel urine from the kidneys into the bladder. The valves at the UVJ prevent retrograde flow.
5. Intravesical Ureter Length:
   
   • The intravesical part of the ureter is the portion that travels within the bladder wall before opening into the bladder lumen. The length of this intravesical segment contributes to the prevention of reflux.

Understanding the anatomy and functional aspects of the ureter-bladder relationship is crucial for normal urine flow and the prevention of conditions such as vesicoureteral reflux, where urine can flow backward from the bladder into the ureters.

Question 5

Microscopic of lymph node

Answer 5

A lymph node, when observed under a microscope, exhibits a complex structure that reflects its vital role in the immune system. Here are the key components of a lymph node at the microscopic level:

1. Capsule:
   
   • The outermost layer is the fibrous capsule, a connective tissue structure that surrounds the entire lymph node.
2. Trabeculae:
   
   • Extensions of the capsule, known as trabeculae, penetrate the interior of the lymph node, providing support and creating compartments within.
3. Cortex:
   
   • The cortex is the outer region of the lymph node. It contains follicles, which are clusters of B cells, and is involved in the primary immune response.
4. Paracortex:
   
   • The paracortex is the middle region of the lymph node and contains T cells. It plays a crucial role in the immune response by facilitating interactions between T cells and antigen-presenting cells.
5. Medulla:
   
   • The innermost region is the medulla, which contains medullary cords and sinuses. Medullary cords consist of B cells, plasma cells, and macrophages, while sinuses are spaces that allow the flow of lymph.
6. Medullary Sinuses:
   
   • Medullary sinuses are interconnected spaces that collect lymph filtered through the lymph node. They contain immune cells and serve as conduits for lymphatic fluid.
7. Germinal Centers:
   
   • Germinal centers are areas within follicles where B cells proliferate and differentiate, producing antibodies in response to antigens.
8. Afferent and Efferent Lymphatic Vessels:
   
   • Lymph enters the lymph node through afferent lymphatic vessels and exits through efferent lymphatic vessels. This flow allows the lymph node to filter and process lymphatic fluid.
9. Hilum:
   
   • The hilum is a concave region where blood vessels and efferent lymphatic vessels enter and exit the lymph node.

Under the microscope, the lymph node’s intricate structure reflects its role in filtering lymph, initiating immune responses, and coordinating the activities of various immune cells.

Question 6

Describe the sternocostal joint

Answer 6

Also: when you raise your arm, reaching overhead, the rib cage also raised.
The sternocostal joints are the articulations between the sternum and the costal cartilages, forming connections between the bony sternum and the cartilaginous portions of the ribs. There are two types of sternocostal joints: the true or synchondral joints and the false or synovial joints.

1. True or Synchondral Sternocostal Joints:
   
   • These joints are the connections between the upper seven ribs and the sternum.
   • The costal cartilages of the first seven ribs articulate directly with the sternum through hyaline cartilage, forming synchondroses.
   • The cartilages attach to the sternum, creating a flexible and slightly movable junction.
2. False or Synovial Sternocostal Joints:
   
   • The false sternocostal joints involve the articulations of the costal cartilages of the 8th, 9th, and 10th ribs with the sternum.
   • These joints are considered false because they have a small amount of synovial joint characteristics, making them more mobile compared to the true sternocostal joints.
   • The 8th, 9th, and 10th ribs’ costal cartilages do not attach directly to the sternum but instead connect to the cartilage of the rib just above, forming synovial-type joints.

Key Points:
- The sternocostal joints collectively contribute to the flexibility of the rib cage, allowing movements during breathing.
- The true sternocostal joints provide stability and limited movement, while the false sternocostal joints offer more mobility due to the synovial characteristics.
- The costal cartilages act as shock absorbers, distributing forces and reducing impact on the rib cage.
- The costal cartilages’ flexibility is essential for the expansion and contraction of the thoracic cavity during respiration.
The first sternochondral joint is different from the other 7 because it is considered as primary cartilaginous joint meaning almost no movement.
This aspect is very important during mechanical ventilation. As the ribs move up and down and their anterior ends elevate, this nonmoveable sternochondral joint helps to automatically move the sternum upwards and outwards (‘pump handle’ movement). Which elevates the ribs.

Question 7

Describe the relationship between uterine artery and the ureters

Answer 7

The uterine artery crosses the ureter superiorly at the level of the lateral part of the uterine cervix below the isthmic part of the uterus, explaining why the ureter is at greater risk of injury during pelvic and gynecologic surgeries.

Question 8

Describe foramen ovale and the ductus arteriosus
Bypass the lungs

Answer 8

Sure, let’s explore the anatomical features of the Foramen Ovale and the Ductus Arteriosus:

Foramen Ovale:
1. Location:
- Found in the fetal heart, it’s an opening between the atria (upper chambers).
- Specifically, it’s in the interatrial septum, the wall that separates the left and right atria.

2. Function:
   
   • Allows blood to bypass the lungs in the fetal circulation.
   • Connects the right atrium to the left atrium, providing a shortcut for oxygenated blood to move directly from the right side to the left side of the heart.
3. Closure:
   
   • Typically, the foramen ovale closes shortly after birth as a part of the normal physiological changes during the transition from fetal to postnatal circulation.
   • In some individuals, it may remain partially open or patent, but this is generally without significant impact.

Ductus Arteriosus:
1. Location:
- Another fetal structure, the ductus arteriosus is a short, muscular blood vessel.
- Connects the pulmonary artery (from the right ventricle) to the aorta (which carries blood to the rest of the body).

2. Function:
   
   • Similar to the foramen ovale, it allows blood to bypass the fetal lungs.
   • Diverts a portion of the blood directly from the pulmonary artery to the aorta.
3. Closure:
   
   • The ductus arteriosus usually closes shortly after birth, triggered by the increase in oxygen levels after the first breath.
   • Once closed, it becomes the ligamentum arteriosum, a fibrous remnant.

Postnatal Significance:
- The closure of these structures is essential for the establishment of the adult circulatory system, separating the systemic and pulmonary circulations and ensuring efficient oxygenation of the blood.

Understanding the fetal structures like the Foramen Ovale and Ductus Arteriosus is crucial for healthcare professionals managing neonatal care and congenital heart conditions.

Question 9

Describe the axillary lymph nodes, their arrangement and relationships

Answer 9

Axillary lymph center-Rotter’s node
5 groups; Lateral, central, subclavicular, pectoral group and subcapsular group. Each group have more than 3 lymph nodes. Collect lymph from upper limb, breasts, subcapsular area, thorax.
Rotter’s node located in the interpectoral area in between pectoralis major and minor.
There is very large amount of lymphatic vessels in the region of nipple.

Question 10

Microscopic anatomy of the esophagus

Answer 10

1-Mucosa: Innermost layer facing the lumen, non-keratinized stratified squamous epithelium.
2-Submucosa:CT layer, contains blood vessels, lymphatics and nerves that support the mucosa. Esophageal submucosal glands can be present providing lubrication.
3-Muscularis Externa: Upper third-skeletal muscles for voluntary control
Middle third- skeletal+smooth muscle
Lower third- Smooth muscle
Sphincters- upper and lower esophageal sphincters regulate the movement of food.
4-Adventitia: Outermost layer: Composed of CT that anchors the esophagus to surrounding structures.
Simple tubular glands found in the submucosa of the upper part of the esophagus

Question 11

Flexor digitorum superficialis innervation, action, origin
FDS

Answer 11

Flexor Digitorum Superficialis is the largest muscle in the anterior forearm. It is located in the middle compartment of the forearm.
2 origins: Humeroulnar head originated from the medial epicondyle of the humerus and radial head originated from the medial radial surface.
Its large muscular belly courses distally towards the wrist where it splits into four tendons and attaches to the middle phalanges of the 2-5th digits of the hand. Due to their superficial location, these tendons can be easily palpated on the distal part of the forearm.
Action: flexion of the wrist and fingers except thumb.
Innervation: Median nerve C8,T1
Blood supply: Ulnar artery, radial artery, median artery.

Question 12

microscopic anatomy of the duodenum

Answer 12

The microscopic anatomy of the duodenum reveals several distinctive features:

1. Mucosa:
   
   • The mucosal lining consists of simple columnar epithelium.
   • Numerous intestinal glands (crypts of Lieberkühn) are present, contributing to the secretion of digestive enzymes and mucus.
2. Villi and Microvilli:
   
   • The mucosal surface is characterized by finger-like projections called villi, which increase the absorptive surface area.
   • Each epithelial cell on the villi has microvilli, forming the “brush border,” which further enhances absorption.
3. Submucosa:
   
   • The submucosa contains larger blood vessels, lymphatic vessels, and submucosal glands.
4. Muscularis Externa:
   
   • The muscularis externa consists of two layers of smooth muscle: an inner circular layer and an outer longitudinal layer. These layers contribute to peristalsis for the movement of chyme.
5. Sphincters:
   
   • The duodenum has two important sphincters:
     
     • Superior duodenal sphincter (of Oddi): Regulates the flow of bile and pancreatic juice from the common bile duct and main pancreatic duct into the duodenum.
     • Inferior duodenal sphincter: Regulates the passage of chyme from the stomach into the duodenum.
6. Brunner’s Glands:
   
   • Brunner’s glands are found in the submucosa of the duodenum, particularly in the first part. They secrete alkaline mucus, helping to neutralize acidic chyme from the stomach.

Understanding these microscopic features is crucial for grasping the duodenum’s role in digestion and absorption processes.

Question 13

cruciate ligaments

Answer 13

PCL: Originating from the posterior intercondylar area of the tibia and inserting onto the anterior aspect of the medial femoral condyle.
Function of the PCL: prevents excessive backward movement of the tibia relative to the femur. Rotational stability.
Car accidents are the main injury
ACL:
Anterior intercondylar area of the tibia and inserts onto the posterior aspect of the lateral femoral condyle.
Function: Prevents excessive forward movement of the tibia relative to the femur.
Injuries: ACL injuries often occur during sports activities that involve sudden stops, change in direction.
It also provide stability when rapid acceleration and decelerations.

Question 14

left lung macro-anatomy

Answer 14

The left lung is slightly smaller than the right lung due to the cardiac notch and is positioned higher to accommodate the heart. It has 2 lobes; superior and inferior it lacks middle lobe.
The aorta runs alongside the left lung.
Esophagus is situated posterior to the left lung.
Spleen and stomach positioned in the abdominal region inferior to the left lung.

Question 15

cornu of uterus and its relationship with nearby structures

Answer 15

It refers to the horn-like upper parts of the uterus where fallopian tubes attach.
1-fallopian tubes extend laterally from each Cornu. These tubes are responsible for transporting eggs from ovaries to the uterus.
Round ligaments: The round ligaments of the uterus extend from the cornua to the labia majora, providing support to the uterus and helping to maintain its position.
Broad ligament attaches to the sides of the uterus and extends to the pelvic sidewalls.
Ovaries: Not directly attached to the cornua, the ovaries are nearby reproductive organs. The release of eggs(ovulation) occurs from the ovaries and is part of the menstrual cycle.

Question 16

peripheral attachments of the diaphragm

Answer 16

The diaphragm, a large muscle separating the thoracic and abdominal cavities, has peripheral attachments that include:

1. Sternal Part: Attaches to the xiphoid process of the sternum.
2. Costal Part: Attaches to the internal surface of the lower six ribs and their costal cartilages. (T7-T12)
3. Lumbar Part: Attaches to the vertebral bodies of the upper three lumbar vertebrae and the intervening intervertebral discs.

These peripheral attachments contribute to the overall support and function of the diaphragm.

Question 17

Insertions, innervation, vascularisation and actions of the supraspinatus muscle

Answer 17

Supraspinatus muscle is one of the rotator cuff muscle located in the posterior scapular region, extending from supraspinous fossa of scapula to the greater tubercle of the humerus.
Innervated by suprascapular nerve C5-C6
Vascularization: Suprascapular artery, which is a branch of the thyrocervical trunk.
Actions: Initiates abduction first 15º, later deltoids.
It stabilizes the glenohumeral joint, especially during the initial phase of arm movement.
Assist in external rotation of the arm.

Question 18

Elastic membranes of the larynx

Answer 18

The larynx contains several important membranes that contribute to its structure and function. Here are some key membranes of the larynx:

1. Thyrohyoid Membrane: This membrane connects the thyroid cartilage to the hyoid bone. It helps suspend the larynx in the neck and allows for some degree of movement.
2. Cricothyroid Membrane (Conus Elasticus): This elastic membrane forms the lower part of the laryngeal skeleton and connects the cricoid cartilage to the thyroid cartilage. It provides support and elasticity to the vocal folds.
3. Quadrangular Membrane: This membrane extends between the lateral and medial aspects of the arytenoid cartilages. It contributes to the formation of the vestibular folds (false vocal cords) and helps enclose the laryngeal ventricle.
4. Cricotracheal Membrane: This membrane connects the cricoid cartilage to the trachea. It plays a role in maintaining the stability and integrity of the larynx.

These membranes, along with the cartilages and muscles of the larynx, work together to regulate airflow, protect the airway, and produce sound during speech and phonation.

Question 19

Uterine angles

Answer 19

1. Anteversion: Anteversion refers to the forward tilt or inclination of the entire uterus in relation to the vagina. In other words, it describes the angle formed between the long axis of the uterus and the long axis of the vagina when the uterus is tilted forward. Normally, the uterus is anteverted, meaning it tilts forward toward the bladder.
2. Anteflexion: Anteflexion refers to the forward bend or flexion of the body of the uterus relative to the cervix. It describes the angle formed between the body and cervix of the uterus. The uterus is anteflexed when the body bends forward at the level of the cervix. This is a normal anatomical variation.

Question 20

Bicuspid valve
(Mitral valve)

Answer 20

Located between left atrium and ventricle. 2 cusps;
Anterior cusp: Larger of the two, facing more anteriorly
Posterior cusp: smaller facing posteriorly
1-papillary muscles connected to the AV valves.
2-Chordae Tendineae: strong, fibrous cords that connect the edges of the cusps to the papillary muscles in the left ventricle.
Anterior, posterior, intermediate papillary muscle
3-Annulus: Fibrous ring-like structure that support the valve and provide attachment for the leaflets.
4-Commissures: The points where the edges of the cusps meet, forming valve’s closure line.
Vestibule: smooth surface where the opening is placed.

Question 21

Microscopic anatomy of the stomach

Answer 21

1-layers of the stomach:
Mucosa; the innermost layer consisting epithelium(simple columnar cells), lamina propria(CT) and muscularis mucosae(smooth muscle layer).
Submucosa containing blood vessels, lymphatics and CT.
Muscularis externa: Inner Oblique/Middle circular/Outer Longitudinal.
Serosa(or Adventitia): Outermost layer providing protection and support.
2-Gastric glands: Mucous cells, Parietal cells(HCl production), Chief cells(secrete pepsinogen)
3- Blood supply: Celiac artery

Question 22

Describe the structure of the intervertebral disc

Answer 22

Fibrocartilaginous structure found between adjacent vertebral discs. 2 main components;
1-Annulus Fibrosus: The outer portion of the intervertebral disc is composed of fibrous tissue. It is organized into concentric layers or lamallae made of fibrocartilage. Each lamellae consist of collagen fibers arranged in a crisscross pattern. Annulus fibrosus provides strength and stability to the intervertebral disc, resisting tension and containing the gel-like nucleus pulposus.
2-Nucleus pulposus: The inner core of the intervertebral disc is called nucleus pulposus.
It is gelatinous, mucoid substance with a high water content. The nucleus pulposus providing flexibility and resistance to compression. It act as a shock absorber. It allows the spine to bend and flex.
3-Vertebral endplates: Upper and lower surfaces of the intervertebral discs, allowing nutrients and fluids to diffuse between the disc and the vertebral bodies.
4-Avascular: meaning it lacks direct blood supply.
5-Innervation: The outer layers of the annulus fibrosus are innervated, providing the disc with sensory nerve fibers. This makes the outer layers more susceptible to pain, contributing to conditions like disc herniation.

Question 23

Describe the tricuspid valve

Answer 23

Found between the right ventricle and atrium.
Leaflets: 3 cusps named anterior, posterior and septal leaflets.
2-chardae Tendineae:Thin fibrous cords called chordae tendineae connect the free edges of the valves to the papillary muscles found in the ventricle.
3-Papillary muscles

Question 24

Describe the macroscopic anatomy of the pylorus

Answer 24

The pylorus is a part of the stomach that connects to the small intestine. Here’s a description of its macroscopic anatomy:

Location:
The pylorus is situated at the distal end of the stomach, forming the junction between the stomach and the duodenum (the first part of the small intestine).

Components:
1. Pyloric Antrum: This is the initial portion of the pylorus, located closest to the body of the stomach. It is larger and more distensible than the pyloric canal.

2. Pyloric Canal: This is the narrower, more muscular portion of the pylorus. It serves as a passage for the partially digested food (chyme) to enter the duodenum.

Muscular Features:
The muscular structure of the pylorus is crucial for regulating the passage of food from the stomach to the small intestine. It consists of two main muscle layers:

1. Circular Muscle Layer (Thick Muscularis Externa): This layer, known as the pyloric sphincter or pyloric circular muscle, forms a ring around the pyloric orifice. It acts as a sphincter to control the release of chyme into the duodenum.
2. Longitudinal Muscle Layer: This layer runs along the length of the pyloric canal and aids in the peristaltic movements that propel chyme into the small intestine.

Pyloric Sphincter:
The pyloric sphincter is a specialized muscle at the junction of the stomach and the duodenum. It controls the flow of chyme from the stomach into the duodenum, allowing small amounts to pass through at a time.

Function:
The primary function of the pylorus is to regulate the release of chyme, the semi-liquid mixture of food and digestive juices, from the stomach into the small intestine. This controlled release ensures that the small intestine receives properly processed food for further digestion and absorption.

In summary, the macroscopic anatomy of the pylorus involves distinct anatomical components, including the pyloric antrum and pyloric canal, along with specialized muscular structures such as the pyloric sphincter, all working together to facilitate the controlled passage of partially digested food into the small intestine.

Question 25

Describe the structure of Bowman’s capsule

Answer 25

Bowman’s capsule, also known as the renal corpuscular capsule, is a crucial structure in the nephron, the functional unit of the kidney. Here’s a detailed explanation of its structure:

1. Location: Bowman’s capsule is located at the beginning of each nephron, specifically in the renal cortex of the kidney.
2. Composition:
   
   • Parietal Layer: This is the outer layer of Bowman’s capsule. It is a simple squamous epithelium that surrounds the glomerulus and forms the capsule’s wall.
   • Visceral Layer (Podocytes): This inner layer is made up of specialized cells called podocytes. Podocytes have finger-like projections called pedicels that wrap around the glomerular capillaries.
3. Space or Capsular Space (Bowman’s Space):
   
   • Between the parietal and visceral layers, there is a cavity known as Bowman’s space. It’s the initial part of the renal tubule where the filtrate from the blood collects before moving into the renal tubules.
4. Glomerulus: This is a network of tiny blood vessels (capillaries) contained within Bowman’s capsule. The glomerulus is the site of ultrafiltration, where blood is filtered to form the initial urine filtrate.
5. Filtration Membrane:
   
   • Endothelial Cells: These cells make up the walls of the glomerular capillaries.
   • Basement Membrane: A gel-like substance that lies between the endothelial cells and the podocytes. It acts as a selective barrier to filter substances based on size and charge.
   • Slit Diaphragms: Specialized membrane proteins between the pedicels of adjacent podocytes. They contribute to the selective permeability of the filtration membrane.
6. Filtration Process: Blood enters the glomerulus through the afferent arteriole and leaves via the efferent arteriole. The pressure in the glomerular capillaries forces small molecules, like water, electrolytes, and waste products, into Bowman’s space. Larger molecules like proteins and blood cells are retained.

In summary, Bowman’s capsule, with its parietal and visceral layers, along with the glomerulus and the associated filtration membrane, plays a crucial role in the initial filtration of blood and the formation of the primary urine filtrate in the kidneys.

Question 26

Describe the contents of the carpal tunnel

Answer 26

Passageway found on anterior wrist for structures passing between anterior forearm and hand

Floor: Carpal groove
Roof: Flexor retinaculum

Contents: Flexor digitorum superficialis tendons
Flexor digitorum profundus tendons
Flexor pollicis longus tendon
Median nerve

Question 27

Describe the posterior wall of the inguinal canal

Answer 27

Posterior wall is divided into 3 parts;
1- Most lateral and posterior wall, thick transversalis fascia(hesselbach ligament)-congenital hernia
2-Only transversalis fascia. Located medially to the inferior epigastric vessels. Acquired hernias
3-Transversalis fascia and lacunar ligament. It is near to the pubic symphysis.
Congenital h-Bowel in the spermatic cords
Acquired h- Bowel parallel to the spermatic cord.

Question 28

Describe the location of the thymus, its relations with other anatomical structures and the microscopic anatomy

Answer 28

Location:
Located in the superior mediastinum, which is the region of thoracic cavity above the heart and between the lungs. It lies anteriorly to the great vessels such as aortic arch or brachiocephalic veins. Its inferior border reaches the level of the fourth costal cartilage.

The thymus has several important anatomical relations:

1. Anterior Relations:
   
   • Anterior to the thymus is the sternum (breastbone).
2. Posterior Relations:
   
   • Posterior to the thymus are the great vessels, including the aortic arch and the brachiocephalic veins.
3. Inferior Relations:
   
   • Inferior to the thymus lies the pericardium and the upper part of the heart.
4. Superior Relations:
   
   • Superiorly, it extends to the lower part of the thyroid gland.
5. Lateral Relations:
   
   • On each side, the thymus is in proximity to the pleura and lungs.
     Microscopic anatomy:

The thymus is a primary lymphoid organ located in the anterior mediastinum, above the heart and behind the sternum. It plays a crucial role in the development and maturation of T-lymphocytes, which are essential components of the immune system. Microscopically, the thymus is composed of several distinct structural components, each with specialized functions. Here’s a detailed explanation of the microscopic anatomy of the thymus:

1. Thymic Lobules:
   
   • The thymus is divided into lobules by connective tissue septa.
   • Each thymic lobule consists of a cortex and a medulla.
2. Cortex:
   
   • The cortex is the outer region of the thymic lobule.
   • It contains densely packed lymphocytes, primarily thymocytes, which are immature T-cells undergoing differentiation and maturation.
   • Within the cortex, thymocytes proliferate and undergo positive and negative selection processes to ensure the development of functional T-cells capable of recognizing self-antigens without causing autoimmune reactions.
3. Medulla:
   
   • The medulla is the inner region of the thymic lobule.
   • It contains fewer lymphocytes compared to the cortex and is characterized by the presence of Hassall’s corpuscles, which are concentrically arranged structures composed of epithelial cells.
   • Hassall’s corpuscles are thought to play a role in the maturation and selection of T-cells within the thymus.
4. Epithelial Reticular Cells:
   
   • Epithelial reticular cells are a specialized type of stromal cell found throughout the thymus.
   • They provide structural support to the thymic microenvironment and create a network of reticular fibers that help organize and compartmentalize thymic tissue.
   • Epithelial reticular cells also play important roles in regulating thymocyte development and maturation through cell-cell interactions and the secretion of various cytokines and growth factors.
5. Blood-Thymus Barrier:
   
   • The thymus is surrounded by a blood-thymus barrier, which consists of specialized endothelial cells lining blood vessels within the organ.
   • This barrier regulates the entry of circulating immune cells and antigens into the thymus, ensuring the integrity of the thymic microenvironment and the proper development of T-cells.

Overall, the microscopic anatomy of the thymus reflects its role as a primary lymphoid organ involved in the development and maturation of T-lymphocytes. Its distinct structural components, including the cortex, medulla, epithelial reticular cells, and blood-thymus barrier, work together to create an environment conducive to T-cell development and selection.

Question 29

Describe the anterior relationship of the left kidney

Answer 29

Certainly! The left kidney is an important organ with various anatomical relationships. Here’s a detailed explanation of its anterior relationships:

1. Stomach:
   
   • The upper part of the left kidney is related to the greater curvature of the stomach.
2. Spleen:
   
   • The left kidney is in close proximity to the spleen, and these organs are often found in the left upper quadrant of the abdomen.
3. Pancreas:
   
   • The pancreas lies in close association with the left kidney. The pancreatic tail may extend near the hilum of the left kidney.
4. Left Suprarenal Gland (Adrenal Gland):
   
   • The left suprarenal gland is situated above the upper pole of the left kidney.
5. Splenic Flexure of the Colon:
   
   • The splenic flexure of the colon is in the vicinity of the left kidney.
6. Left Colic (Splenic) Flexure:
   
   • The left colic (splenic) flexure of the colon is also associated with the left kidney.
7. Descending Colon:
   
   • The descending colon runs along the lateral aspect of the left kidney.

These anatomical relationships are important for understanding the positional and functional aspects of the left kidney in the abdominal cavity.

Question 30

Gross anatomy of the pleurae

Answer 30

The pleurae are a pair of serous membranes that envelop the lungs and line the thoracic cavity. There are two layers of pleurae for each lung: the visceral pleura, which covers the lung surface, and the parietal pleura, which lines the inner surface of the thoracic cavity.

1. Visceral Pleura:
- Location: Directly adherent to the lung tissue.
- Function: Protects and covers the lungs, providing a smooth, frictionless surface for movement during respiration.

2. Parietal Pleura:
- Costal Pleura: Lines the inner surface of the thoracic wall (ribs, intercostal muscles, and sternum).
- Diaphragmatic Pleura: Covers the superior surface of the diaphragm.
- Mediastinal Pleura: Surrounds the mediastinum (central compartment of the thoracic cavity).

3. Pleural Cavity:
- Location: The potential space between the visceral and parietal pleurae.
- Function: Contains a small amount of pleural fluid, reducing friction during respiratory movements.

4. Pleural Reflections:
- Costomediastinal Recess: A potential space where the costal and mediastinal pleurae meet.
- Costodiaphragmatic Recess: A potential space where the costal and diaphragmatic pleurae meet.

5. Innervation and Blood Supply:
- Nerve Supply: Phrenic nerve (mainly responsible for sensory innervation).
- Blood Supply: Intercostal and bronchial arteries.

Clinical Significance:
- Pleural Effusion: Accumulation of excess fluid in the pleural cavity.
- Pneumothorax: Presence of air in the pleural cavity.
- Pleural Mesothelioma: Cancer affecting the pleura.

Understanding the gross anatomy of the pleurae is crucial for comprehending respiratory mechanics and diagnosing thoracic conditions.

Question 31

Prostatic urethra

Answer 31

The prostatic urethra is the part of the urethra that passes through the prostate. It is about 3-4 cm long and extends between the preprostatic and the membranous part of the urethra. The posterior part of the prostatic urethra is marked by an elevation known as the urethral crest.he prostatic sinuses are two depressions on each side of the crest where the prostatic ducts empty prostatic fluid into the urethral lumen. The urethral crest enlarges to form a rounded elevation which is known as the seminal colliculus. In the center of the seminal colliculus is a small indentation, the prostatic utricle, an embryological remnant that is thought to be the homologue of the uterus. The ejaculatory ducts also open up in the prostatic urethra, on each side of the prostatic utricle. These ducts carry sperm from the testes and fluid from the seminal vesicles into the urethra. Thus the urinary and reproductive tracts merge at this point.

The prostatic urethra is a common site of obstruction to the outflow of urine in patients with benign hypertrophy of the prostate

Question 32

Sinoatrial node

Answer 32

Pacemaker of the heart, cluster of cells located in the right atrium located near to the orifice of the SVC.
Composed of specialized cardiac muscle cells. Structurally distinct from the surrounding atrial muscle cells. Ovoid shape.
Initiates electrical impulses that coordinate the heartbeat. Generates rhythmic action potentials due to the spontaneous depolarization of its cells due to movement of ions across its membrane.
Supplied by the Sinoatrial nodal artery which is a branch of the right coronary artery

Question 33

Ligaments of liver

Answer 33

1-Round ligament or Ligamentum Teres:
Origin: Fetal umbilical vein
Runs within the free edge of the falciform ligament
Extends from umbilicus to the liver.
2-Falciform Ligament: broad thin fold of peritoneum that attaches the lvier to the anterior abdominal wall and the diaphragm.
Divides the liver into left and right lobes.
Contains the ligamentum teres
3-Coronary ligaments: fold of peritoneum that attach the liver to the diaphragm. 2 coronary ligaments
Left CL; left lobe to the diaphragm
Right CL; right lobe to the diaphragm
Form a crown-like structure around the bare area of the liver.
Triangular ligament: Results from the union of the coronary and falciform ligaments. Extend from the liver to the diaphragm
Ligamentum venosum: is a fibrous remnant of the ductus venosus, which shunted blood from the umbilical vein to the IVC in the fetal circulation. It attach liver to the IVC and help stabilizing the liver in the abdominal region
Lesser omentum: connects liver to the lesser curvature of the stomach. It contains the right and left gastric arteries and veins.
Hepatogastric ligament: connects liver to the greater curvature of the stomach.

Question 34

Macro anatomy of transverse colon

Answer 34

The transverse colon is a part of the large intestine and has specific anatomical features:

1. Location:
   
   • The transverse colon is the longest and most movable part of the colon.
   • It extends horizontally across the upper abdomen, below the stomach and liver.
2. Shape and Orientation:
   
   • It has a somewhat flattened or “U”-shaped appearance.
   • It forms a loop, and its position can vary based on an individual’s anatomy.
3. Attachments:
   
   • It is attached to the posterior abdominal wall by the transverse mesocolon, a peritoneal fold that supports and suspends it.
4. Connections:
   
   • The right portion of the transverse colon connects to the ascending colon.
   • The left portion connects to the descending colon.
5. Flexures:
   
   • The transverse colon has two flexures:
     
     • Right Colic Flexure (Hepatic Flexure): This is the bend where the ascending colon turns into the transverse colon.
     • Left Colic Flexure (Splenic Flexure): This is the bend where the transverse colon turns into the descending colon.
6. Blood Supply:
   
   • The transverse colon receives its blood supply primarily from the middle colic artery, a branch of the superior mesenteric artery.
7. Function:
   
   • The primary function of the transverse colon is to further absorb water and electrolytes from the remaining indigestible food matter, forming solid feces.

Understanding the macroscopic anatomy of the transverse colon provides insights into its role in the digestive process and its connections within the abdominal cavity.

Question 35

Macro anatomy of the trachea

Answer 35

The trachea, commonly known as the windpipe, is a tubular structure in the respiratory system. Here are key aspects of its macroscopic anatomy and relationships:

1. Location:
   
   • The trachea is located anterior to the esophagus in the neck and upper chest.
   • It begins at the level of the sixth cervical vertebra (C6) and extends to the level of the fifth thoracic vertebra (T5).
2. Structure:
   
   • It is a flexible, cylindrical tube composed of cartilaginous rings connected by fibrous tissue and smooth muscle.
   • The trachea is approximately 10-12 cm long in adults.
3. Divisions:
   
   • The trachea divides into the right and left main bronchi at the carina, which is a cartilaginous ridge.
4. Cartilaginous Rings:
   
   • The trachea is reinforced by C-shaped cartilaginous rings that provide support to prevent collapse.
   • The open part of the C-shaped rings faces the posterior side of the trachea.
5. Relations:
   
   • Anteriorly, the trachea is related to the sternum.
   • Posteriorly, it is in contact with the esophagus.
6. Blood Supply:
   
   • The blood supply to the trachea comes from the inferior thyroid arteries, branches of the thyrocervical trunk.
7. Nerve Supply:
   
   • The trachea is innervated by the recurrent laryngeal nerves, which are branches of the vagus nerve (cranial nerve X).
8. Function:
   
   • The trachea serves as a passageway for air to travel between the larynx and the bronchi, facilitating the exchange of gases during respiration.

Understanding the macroscopic anatomy of the trachea helps in appreciating its role in the respiratory system and its relationships with surrounding structures.

Question 36

Median nerve: origin, course and territory of innervation

Answer 36

Major nerve that innervated the upper limb, originating from the brachial plexus.
Origin: lateral and medial cords of the brachial plexus. Specifically, it receives fibers from spinal nerve roots C5 to T1.
Course: after its formation the median nerve descends down the arm, running alongside the brachial artery. Passes the cubical fossa, in the forearm pass between the flexor digitorum superficialis and profundus muscles. It continues into hand through carpal tunnel.
Branches and innervation:
Innervates the flexor and pronator muscles in the anterior compartment of the forearm (except the flexor carpi ulnaris and part of the flexor digitorum profundus, innervated by the ulnar nerve). Also supplies innervation to the thenar muscles and lateral two lumbricals in the hand.
Sensory innervation: Lateral palm and lateral first 3,5 fingers.

Question 37

Describe the vesicouterine pouch: limits and content

Answer 37

Fold of peritoneum
Potential space in the female pelvis situated between the bladder(anteriorly) and the uterus(posteriorly).
Limits: posterior surface of the bladder-anterior surface of the uterus.
Contents: small amount of peritoneal fluid and is part of the peritoneal cavity. It is important for its role as a potential space that allows mobility and movement between the bladder and uterus.

Question 38

Describe the interatrial septum, with particular focus on the fossa ovalis

Answer 38

Interatrial septum: divides 2 atria of the heart.
Fossa ovalis is a depressed structure located in the superior portion of the interatrial septum in the right atrium.
Fossa ovalis is the remnant of the foremen ovale, allowing blood to bypass lungs. After lungs become functional foramen ovale generally closes and leaving fossa ovalis as a remnant.

Question 39

Deep femoral artery: anatomy, course branches and supply

Answer 39

The profunda femoris (deep femoral) artery is the largest branch of the femoral artery.

It arises within the anterior thigh, and travels deeply to supply the muscles and skin of the lateral, medial and posterior thigh.

Course
The profunda femoris artery arises from the posterolateral aspect of the femoral artery proper, approximately 3cm distal to the inguinal ligament. It passes inferiorly and posteriorly into the thigh, along the medial aspect of the femur.

Shortly after its origin, it gives rise to the medial and lateral circumflex femoral arteries.

It travels between the pectineus and adductor longus muscles of the medial thigh compartment, and then between the adductor longus and brevis as it moves inferiorly.

The profunda femoris then pierces the adductor magnus muscle, terminating as a perforating vessel within the thigh.

Supply
The profunda femoris artery gives rise to two major vessels and (usually) three perforating vessels, which supply the muscles and skin of the lateral, medial and posterior thigh:

Lateral circumflex femoral artery – supplies the muscles of the anterolateral thigh (vastus lateralis, tensor fascia lata, lateral aspect of rectus femoris and vastus intermedius) and overlying subcutaneous tissue and skin.
Medial circumflex femoral artery– supplies the head and neck of the femur, muscles of the medial thigh, and overlying subcutaneous tissue and skin.
Perforating arteries (x3) – supplies the muscles of the posterior thigh and overlying subcutaneous tissue and skin.

Question 40

Thoracic duct: anatomical relationships, origin tributaries

Answer 40

The thoracic duct is 38 to 45 centimeters long and 2 to 5 millimeters in diameter. It runs from the superior aspect of the cisterna chyli, a lymph sac at the L2 vertebral level, to the lower cervical spine. From the cisterna chyli, the duct continues superiorly, running between the aorta and the azygous vein and anterior to the vertebral column. The thoracic duct ascends through the aortic hiatus of the diaphragm entering the posterior mediastinum, still to the right of the vertebral column. It courses posterior to the esophagus at the T7 level and crosses over the midline to the left side of the thorax around the T5 vertebral level. As it continues upward, it runs behind the aorta and to the left of the esophagus ascending 2-3 cm above the clavicle. In the superior mediastinum, it passes behind the left common carotid artery, the vagus nerve, and the internal jugular vein. It then descends to empty into the junction of the left subclavian and internal jugular veins.

Question 41

Recto- uterine pouch
(Ben yazdim)

Answer 41

Douglas pouch found in women. Posteriorly limited by anterior wall of the rectum and anteriorly posterior surface of the uterus. Inferior limit or floor; upper part of the posterior vaginal wall
Contents; small amount of fluid allows for mobility and minimizes friction.
Clinical relevance: it is a common site for the accumulation of fluid or blood in cases of pelvic pathology such as pelvic inflammatory disease(PID), endometriosis, ovarian cyst rupture, or ectopic pregnancy. This accumulation of fluid or blood may lead to pain or discomfort.

Question 42

Describe the rectus abdominis sheath

Answer 42

It is a layer of dense regular connective tissue that surrounds the rectus abdominis muscle and helps to maintain anterior abdominal wall.
External oblique muscle aponeurosis= this layer is located anteriorly and laterally
Internal oblique aponeurosis= posteriorly and laterally
Transversus abdominis aponeurosis= deepest layer, lies posteriorly
Linea alba= in the midline of the abdomen the aponeuroses of the internal oblique and transversus abdominis muscles merge and interlace with each other. It is a tough, fibrous band running from xiphoid process to the pubic symphysis.
Lower 1/4 of the muscles are not covered posteriorly by the sheath only anteriorly. The line between the upper three quarters and the lower quarter of the rectus abdominis muscle is called the arcuate line.

besides the rectus abdominis and pyramidalis muscles, the rectus sheath contains the superior and inferior epigastric arteries and veins, lymphatic vessels, termination parts of lower five intercostal nerves (T7-T11).
Superior and inferior epigastric arteries anastomes with each other at the level of the umbilicus after entering the rectus sheath.

Question 43

Describe the common hepatic artery

Answer 43

Abdominal aorta- coeliac trunk-common hepatic artery.
One of the 3 branches of the celiac trunk(Major branch). It supplies oxygenated blood to the liver, gallbladder and some parts of the stomach, pancreas and duodenum.
Course; after arising, travels anteriorly and laterally, passing behind the lesser omentum and to the right portal vein. It then enters the hepatoduodenal ligament where it is referred to as the hepatic artery proper.
Branches:
-Gastroduodenal branch; stomach and proximal duodenum
-proper hepatic; continues towards liver and divides into right and left hepatic arteries.

Question 44

Shape, position, relationships of the cecum and behavior of the peritoneum

Answer 44

It is a pouch shaped or blind ended tube. It situated in the right iliac fossa which is the right lower quadrant of the abdomen but its position can be changed due to the intestine movements.
Anteriorly it is related to the anterior abdominal wall and it is covered by the peritoneum. Medially it is related to the distal ileum. Which it communicates through the iliocecal valve. Laterally the cecum is often related to the ascending colon from which it arises.

The base of the appendix lies on the posteromedial wall of the cecum about 1 to 2 centimeters below the ileocecal junction.

The cecum is supplied by the ileocolic artery, which is a terminal branch of the Superior Mesenteric Artery (SMA). The ileocolic artery gives rise to the appendicular artery to supply the appendix.

The cecum also is located intraperitoneally, but it lacks a mesentery. The cecum is an intraperitoneal organ, however, as it is covered on all sides by peritoneum.

Question 45

Describe the inner configuration of the bladder

Answer 45

Trigone: triangular area defined by 3 openings; two ureteral orifices at the upper corners and the internal urethral orifice at the lower apex. It serves as a landmark for the smooth flow of urine.
Rugae; the mucosal lining forms folding, it is able to expand as it fills with the urine. Increasing its capacity without increasing the internal pressure significantly.
Transitional epithelium; it can be stretched and contract to accommodate changes in the bladder volume. This epithelium is impermeable to urine and helps prevent leakage.
Mucosal glands; secrete mucus to help lubricate the bladder’s inner surface and protect it from irritation caused by urine.
In the ureteral orifices there are valves that prevent back flow of the urine.
Internal urethral orifice; opening through which urine exits the bladder and enters the urethra. Located at the lower apex of the trigone and is surrounded by a internal sphincter muscle.

Question 46

Subcapsularis muscle(origin, insertion and innervation, action)

Answer 46

Origin: The subscapularis muscle originates from the subscapular fossa, which is a depression on the anterior surface of the scapula.

Insertion: It inserts onto the lesser tubercle of the humerus.

Innervation: The subscapularis muscle is innervated by the upper and lower subscapular nerves, which are branches of the brachial plexus (specifically, the posterior cord).

Action: The main actions of the subscapularis muscle include medial rotation of the arm at the shoulder joint and stabilization of the shoulder joint, especially during activities involving overhead motion or throwing. It also assists in adduction and extension of the arm.

Question 47

Microscopic anatomy of the spleen
White-red pulp

Answer 47

An intraperitoneal(except hilum of the spleen) lymphoid organ found on the left side of the abdomen inferior to the diaphragm. The spleen is an organ located in the upper left quadrant of the abdomen, just beneath the diaphragm and behind the stomach. It plays important roles in the immune system, blood filtration, and red blood cell storage and destruction. Microscopically, the spleen is composed of several distinct structures, each with specific functions. Here’s a detailed explanation of the microscopic anatomy of the spleen:

1. White Pulp:
   White pulp is the main lymphoid tissue of the spleen. It is the accumulation of lymphocytes around an arterial vessel. This aggregation of lymphocytes constitutes the lymphoid tissue known as periarterial lymphoid sheath(PALS) and it is the first to react if microbes reach the spleen through the bloodstream.
2. Red Pulp:
   Consist of splenic venous sinuses and cords, linings of splenic macrophages around the sinuses. The central artery from the PALS continues from the white pulp to the red pulp as a capillary. These capillaries empty into splenic cords where macrophages phagocyte old and damaged erythrocytes. From there blood diffuses into splenic sinuses thus returning the venous circulation.
3. Marginal Zone:
   
   • The marginal zone is a transitional region between the white pulp and the red pulp.
   • It contains specialized immune cells, such as marginal zone macrophages and dendritic cells, which play roles in antigen capture and presentation to lymphocytes.
   • The marginal zone serves as a critical site for initiating immune responses against blood-borne pathogens and antigens.
4. Vascular Supply:
   
   • The spleen receives its blood supply from the splenic artery, which branches into smaller arteries as it enters the spleen.
   • The splenic artery gives rise to central arterioles that penetrate the white pulp and give rise to the arteriolar sheaths.
   • Blood from the arterioles flows into the splenic cords and sinuses of the red pulp, where filtration and processing occur.
   • After filtration, blood exits the spleen via the splenic vein, which ultimately drains into the portal venous system.

Overall, the microscopic anatomy of the spleen reflects its dual functions as an immune organ and a blood filter, with specialized structures and cell populations dedicated to these roles.

Question 48

Internal surface of the right ventricle

Answer 48

1-Trabeculae carneae: internal surface of the right ventricle lined with irregular muscular ridges called TC. These trabeculae carneae is more prominent than the left ventricle and serve to strengthen the ventricular wall while preventing the collapse of the cusps.
2-Moderator band(septomarginal trabecula):
Runs between interventricular septum to the base of the anterior papillary muscle. It contains specialized cardiac conducting tissue and serves to conduct electrical impulses from the inter ventricular septum to the anterior papillary muscle, helping to coordinate the contraction of the right ventricle. Also provides structural support to the right ventricle preventing over-distension during contraction.
Papillary muscles: projections of myocardium that attach to the cusps of the tricuspid valve via the chordae tendineae. These muscles contract during ventricular systole to prevent the prolapse of the tricuspid valve cusps into the right atrium, thereby preventing the back flow of blood.
Sinus venarum or smooth areas:
Tricuspid orifice

Question 49

Sample question
Position and relationships of the second portion of the duodenum, also describing the behavior of the peritoneum?

Answer 49

Answer:
The second portion of the duodenum is a relatively short segment of the small intestine that follows the first (or superior) portion of the duodenum and precedes the third (or horizontal) portion. It is approximately 7.5 to 10 centimeters in length and is primarily retroperitoneal, meaning it is located behind the peritoneum.

Position and Relationships:
- The second portion of the duodenum begins at the level of the duodenal bulb, which is situated at the level of the L1 vertebra, descending slightly inferiorly and to the right.
- It runs horizontally across the abdomen, posterior to the head of the pancreas.
- Anteriorly, the second portion of the duodenum is related to the gallbladder and the hepatic flexure of the colon.
- Posteriorly, it is related to the inferior vena cava (IVC), the aorta, the superior mesenteric artery (SMA), and the right renal vessels.

Behavior of the Peritoneum:
- The second portion of the duodenum is mostly retroperitoneal, which means it is located behind the peritoneum. However, its anterior aspect may be partially covered by peritoneum, forming the anterior pararenal space.
- The peritoneum covers the anterior surface of the second portion of the duodenum, forming the anterior pararenal space. This space is anterior to the head of the pancreas and posterior to the peritoneum lining the anterior abdominal wall.
- Posteriorly, the duodenum is in direct contact with the retroperitoneal structures, such as the IVC, aorta, SMA, and right renal vessels, without any peritoneal covering.

In summary, the second portion of the duodenum is primarily retroperitoneal, with its anterior aspect partially covered by peritoneum, forming the anterior pararenal space. It is positioned horizontally across the abdomen, posterior to the head of the pancreas and related to various important structures in the abdominal cavity.