ANATOMY (2024) - PART 2 Flashcards
A complete transection of the tibial division of the sciatic nerve will most likely affect which muscle?
A. Tibialis anterior
B. Vastus lateralis
C. Peroneus longus
D. Semitendinosus
D. Semitendinosus
Rationale: The tibial division of the sciatic nerve innervates the semitendinosus muscle, which is part of the hamstring group.
Note:
* The Sciatic Nerve innervates muscles in the posterior compartment of the thigh (All muscles are innervated by the Tibial Nerve) except for the short head of the biceps femoris, which is supplied by the Common Peroneal Nerve.
* The Common Peroneal Nerve is in a vulnerable position as it winds around the neck of the fibula, and damage to it results in Foot Drop (foot is plantarflexed and inverted).
The following bones make up the orbit, EXCEPT:
A. Ethmoid
B. Sphenoid
C. Frontal
D. Nasal
E. Lacrimal
D. Nasal
Rationale: The nasal bone does not contribute to the formation of the orbit. The orbit is made up of the ethmoid, sphenoid, frontal, lacrimal, maxillary, palatine, and zygomatic bones.
The first order neuron of the ascending tract usually comes from the _____.
A. Dorsal root ganglion
B. Substantia gelatinosa
C. Anterior gray column
D. Receptors
A. Dorsal root ganglion
Rationale: The first-order neurons of the ascending sensory pathways are located in the dorsal root ganglia, which contain the cell bodies of sensory neurons.
A 23 y/o boxer presents with dizziness, vertigo, tinnitus, and fullness of his ears with some hearing loss and was diagnosed to have a perilymphatic fistula. In which of the following structures is perilymph normally found?
A. Saccule
B. Semicircular canals
C. Scala media
D. Scala tympani
D. Scala tympani
Rationale: Perilymph is found in the scala tympani and scala vestibuli of the cochlea. The scala media contains endolymph.
Histology
Choose the correct part of the pituitary: embryologic origin.
A. Pars nervosa: Floor of diencephalon
B. Adenohypophysis: Mesoderm
C. Pars tuberalis: Endoderm
D. Pars intermedia: Neural crest
A. Pars nervosa: Floor of diencephalon
Rationale: The pars nervosa, which is part of the posterior pituitary gland, originates from the floor of the diencephalon.
Which vertebral region has bifid spinous processes?
A. Sacral
B. Thoracic
C. Lumbar
D. Cervical
D. Cervical
Rationale: The cervical vertebrae, particularly C2 to C6, have bifid spinous processes.
Which structure is found deep to the flexor retinaculum?
A. Flexor carpi radialis
B. Ulnar nerve
C. Flexor digitorum profundus
D. Palmaris longus
C. Flexor digitorum profundus
Rationale: The flexor digitorum profundus tendons, along with the median nerve and other flexor tendons, pass deep to the flexor retinaculum through the carpal tunnel.
Wrist: Flexor Retinaculum
• Description: Thickening of deep fascia that holds the long flexor tendons in position at the wrist. It is attached medially to the pisiform bone and the hook of hamate and laterally to the tubercle of the scaphoid and the trapezium bones. The upper border of the retinaculum corresponds to the distal transverse skin crease in front of the wrist and is continuous with the deep fascia of the forearm. The lower border is attached to the palmar aponeurosis.
Structures Anterior to the Flexor Retinaculum (Medial to Lateral)
1. Flexor Carpi Ulnaris Tendon 2. Ulnar Nerve 3. Ulnar Artery 4. Palmaris Longus Tendon (if present) 5. Palmaris Cutaneous Branch of Ulnar Nerve 6. Palmaris Cutaneous Branch of Median Nerve
Structures Posterior to the Flexor Retinaculum (Medial to Lateral)
1. Flexor Digitorum Superficialis Tendons • Posterior to the FDS Tendons, both groups share a common synovial sheath. 2. Flexor Digitorum Profundus Tendons 3. Median Nerve 4. Flexor Pollicis Longus Tendon 5. Flexor Carpi Radialis Tendon
Additional Structures
• Distal Radio-Ulnar Joint Complex (TFCC): Occurs simultaneously, involving the triangular fibrocartilage complex, proximal and distal. • 12 Muscles: Associated with movements of the wrist and hand.
In cases of blunt trauma to the head, blood (hematoma) can easily form around the periorbital area, by spreading through this layer.
A. Skin
B. Connective tissue
C. Aponeurosis epicranialis
D. Loose areolar tissue
E. Pericranium
D. Loose areolar tissue
Rationale: The loose areolar tissue layer (subgaleal space) allows for the easy spread of blood and infection, which can lead to periorbital hematoma (bruising around the eyes).
These nerves regulate blood flow through the kidney by causing vasodilation or vasoconstriction of renal arterioles:
A. Aortic plexus
B. Renal ganglion
C. Celiac plexus
D. Hypogastric nerves
B. Renal ganglion
The renal ganglion refers to a cluster of nerve cell bodies located near the kidneys. It plays a role in the autonomic regulation of renal function, including the modulation of blood flow through vasodilation and vasoconstriction of renal arterioles.
Neuronal degeneration of the basal ganglia is the cause of this disease.
A. Quadriparesis
B. Diplegia
C. Parkinson’s disease
D. Hemiplegia
C. Parkinson’s disease
Rationale: Parkinson’s disease is characterized by neuronal degeneration in the basal ganglia, specifically the substantia nigra, leading to dopamine deficiency and motor symptoms.
The basal nuclei (also known as basal ganglia) play a critical role in various aspects of motor control and learning.
Functions of the Basal Nuclei
Corpus Striatum
- Afferent Information Sources:
1. Cerebral Cortex: Provides input related to motor commands and sensory information.
2. Thalamus: Relays processed sensory and motor signals to the basal nuclei.
3. Subthalamus: Involved in the regulation of motor functions.
4. Brainstem: Contributes to motor control and integrates information from various parts of the brain.
5. Substantia Nigra: Supplies dopamine, crucial for modulating motor control and function.
Which of the following nerves passes through the superficial inguinal ring?
A. Iliohypogastric nerve
B. Obturator nerve
C. Pudendal nerve
D. Ilioinguinal nerve
D. Ilioinguinal nerve
Rationale: The ilioinguinal nerve passes through the superficial inguinal ring and provides sensory innervation to the skin of the groin and upper genitalia.
Which of the following blood flow sequences into the kidney is correct?
A. Renal artery → Arcuate Artery → Interlobar Artery → Segmental Artery → Interlobular Artery →
Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries → … Renal vein
B. Renal artery → Segmental Artery → Interlobar Artery → Arcuate Artery → Interlobular Artery →
Efferent arteriole → Glomerulus → Afferent arteriole → Peritubular capillaries → … Renal vein
C. Renal artery →Segmental Artery → Interlobar Artery → Arcuate Artery → Interlobular Artery →
Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries → … Renal vein
D. Renal artery → Segmental Artery → Interlobular Artery → Arcuate Artery → Interlobar Artery →
Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries → … Renal vein
C. Renal artery → Segmental Artery → Interlobar Artery → Arcuate Artery → Interlobular Artery → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries → … Renal vein
Rationale: This sequence correctly follows the path of blood flow through the kidney from the renal artery to the renal vein, passing through the necessary arteries
-
Renal Medulla:
- Receives significantly less blood flow than the renal cortex.
- This makes the medulla very sensitive to hypoxia and vulnerable to ischemic damage.
-
Left Renal Vein:
- Receives two additional veins:
- Left suprarenal vein
- Left gonadal vein
- Receives two additional veins:
-
Left Kidney in Transplantation:
- The left kidney is often taken during living donor transplantation because it has a longer renal vein.and capillaries.
Of the structures contained within the carotid sheath, which lies posterior?
A. Common carotid artery
B. Internal carotid artery
C. Internal jugular vein
D. Vagus nerve
E. Phrenic nerve
D. Vagus nerve
Rationale: The vagus nerve (CN X) lies posteriorly within the carotid sheath, behind the common carotid artery and internal jugular vein.
Position (Carotid Sheath)
* Common Carotid Artery: medially and inferiorly.
* Internal Carotid Artery: medially and superiorly.
* Internal Jugular Vein: laterally.
* Vagus Nerve: posteriorly.
* Deep Cervical Lymph Nodes: Embedded within the sheath.
Which part of the gastrointestinal tract is classified as a derivative of both the foregut and the midgut?
A. Duodenum
B. Stomach
C. Esophagus
D. Transverse colon
A. Duodenum
Rationale: The duodenum is derived from both the foregut and the midgut, with the transition occurring approximately at the level of the major duodenal papilla.
The planning of sequential movements of the entire body and the conscious assessment of errors are controlled by the _____.
A. Flocculonodular lobe
B. Lateral zone of the cerebellar hemispheres
C. Intermediate zone of the cerebellar hemispheres
D. Vermis
B. Lateral zone of the cerebellar hemispheres
Rationale: The lateral zone of the cerebellar hemispheres is involved in the planning of complex, sequential movements and the conscious assessment of movement errors.
CereBRUM gives commands. CereBELLUM coordinates
Functional Areas of the Cerebellum
Longitudinal Sagittal Zonal Patterns
- The cerebellum is divided into three longitudinal strips, each encompassing:
- Cerebellar Cortex
- Underlying White Matter
- Deep Cerebellar Nuclei
Functional Areas of the Cerebellar Cortex:
- Primary Fissure:
- Divides the anterior and posterior lobes of the cerebellum.
-
Vermis:
- Located along the midline (long axis of the body).
- Functions:
- Controls muscles of the neck, shoulders, thorax, abdomen, and hips.
-
Intermediate Zone:
- Located adjacent to the vermis.
- Functions:
- Controls muscles of the distal parts of the limbs, including the hands and feet.
-
Lateral Zone:
- Located laterally to the intermediate zone.
- Functions:
- Involved in the planning of sequential movements of the entire body.
- Responsible for the conscious assessment of movement errors.
The trachea bifurcates into right and left primary bronchi at the level of what structure?
A. Seventh cervical vertebra
B. First rib
C. Suprasternal (or jugular) notch
D. Plane of the sternal angle
D. Plane of the sternal angle
Rationale: The trachea bifurcates at the level of the sternal angle (T4/T5 vertebral level).
The ligament that extends from the anterior superior iliac spine to the pubic tubercle and forms the lower lateral boundary of the abdominal wall is the:
A. Inguinal
B. Pectineal
C. Ilio-pectineal
D. Lacunar
A. Inguinal
Rationale: The inguinal ligament extends from the anterior superior iliac spine to the pubic tubercle and forms part of the lower boundary of the abdominal wall.
A 25-year-old professional computer gamer has been experiencing tingling and numbness on the tips of the index and middle fingers for several months. Which test will most likely establish your diagnosis?
A. Phalen’s
B. Finkelstein’s
C. Trendelenburg
D. Allen’s
A. Phalen’s
Rationale: Phalen’s test is used to diagnose carpal tunnel syndrome, which commonly causes tingling and numbness in the tips of the index and middle fingers.
The zygomaticus major muscle is innervated by the:
A. Trigeminal nerve (CN V)
B. Facial nerve (CN VII)
C. Oculomotor nerve (CN III)
D. Abducens nerve (CN VI)
E. Vagus nerve (CN X)
B. Facial nerve (CN VII)
Rationale: The zygomaticus major muscle, which is responsible for elevating the corners of the mouth (smiling), is innervated by the facial nerve (CN VII).
Cranial Nerves in the Lower Pons:
- CN VI (Abducens Nerve):
- Function: Innervates the lateral rectus muscle, which abducts the eye.
- Clinical Note: Lesions in CN VI can result in an inability to move the eye laterally, leading to diplopia (double vision).
-
CN VII (Facial Nerve):
-
Function:
- Motor: Innervates muscles of facial expression.
- Sensory: Provides taste sensation to the anterior 2/3 of the tongue.
- Parasympathetic: Supplies glands like the lacrimal (tear) glands, submandibular, and sublingual salivary glands.
- Clinical Note: Damage to CN VII can cause Bell’s palsy, resulting in muscle weakness on one side of the face.
-
Function:
Muscles of Mastication:
- Innervated by CN V (Trigeminal Nerve):
- Lateral Pterygoid: Helps in opening the jaw.
- Medial Pterygoid: Assists in closing the jaw.
- Masseter: Elevates the mandible to close the jaw.
- Temporalis: Elevates and retracts the mandible.
Muscles of Facial Expression:
- Innervated by CN VII (Facial Nerve):
- Frontalis: Raises eyebrows.
- Orbicularis Oculi: Closes the eyes.
- Zygomaticus Major: Elevates the corners of the mouth (smiling).
- Buccinator: Compresses the cheek (e.g., during blowing).
- Orbicularis Oris: Closes and puckers the lips.
- Mentalis: Elevates and protrudes the lower lip (pouting).
Cranial Nerves in the Upper Medulla:
- CN XII (Hypoglossal Nerve):
- Function: Innervates all intrinsic and extrinsic muscles of the tongue except for the palatoglossus (innervated by CN X).
-
Nucleus Ambiguus:
-
Function:
- CN IX and X: Innervate muscles of the pharynx and larynx involved in swallowing and phonation.
- CN XI: Innervates the sternocleidomastoid and trapezius muscles and also assists in swallowing and phonation.
-
Function:
In Wallenberg syndrome, the structure responsible for the analgesia and thermoanesthesia on the ipsilateral side of the face is the _____.
A. Spinothalamic tract
B. Inferior cerebellar peduncle
C. Nucleus and spinal tract of the trigeminal nerve
D. Descending sympathetic tract
C. Nucleus and spinal tract of the trigeminal nerve
Rationale: In Wallenberg syndrome (lateral medullary syndrome), the nucleus and spinal tract of the trigeminal nerve are affected, leading to loss of pain and temperature sensation on the ipsilateral side of the face.
Key Points:
- Contralateral Lesions affect the opposite side of the body.
- Ipsilateral Lesions affect the same side of the body.
Contralateral Lesions (The Rest Ipsilateral):
1. Motor Pathway (Corticospinal Tract):
- Effect: Paresis (weakness)
- Lesion Location: Contralateral to the site of the lesion.
2. DC/ML (Dorsal Column/Medial Lemniscus):
- Effect: Loss of proprioception and vibration sense.
- Lesion Location: Contralateral to the site of the lesion.
3. Spinothalamic Tract:
- Effect: Loss of pain and temperature sensation (PaTe)
- Lesion Location: Contralateral to the site of the lesion.
- Mnemonic: S PagheTTi (highlighting Pain and Temp)
Explanation:
- Contralateral Lesions:
- The pathways that cross to the opposite side (decussate) before reaching their targets result in contralateral effects when damaged.
- Motor Pathway (Corticospinal Tract): Originates in the cortex, crosses at the medulla (pyramidal decussation), affecting the opposite side of the body.
- DC/ML: Sensory pathways for proprioception and vibration cross in the medulla, affecting the opposite side.
- Spinothalamic Tract: Carries pain and temperature sensation, crosses at the spinal cord level, affecting the opposite side.
-
Ipsilateral Lesions:
- Most other pathways and cranial nerves do not cross, resulting in ipsilateral effects when damaged.
If a patient with a laceration on the palmar aspect of the right middle finger is able to flex the PIP joint but is unable to flex the DIP joint, this implies injury to which structure?
A. Ulnar nerve
B. Flexor digitorum profundus
C. Median nerve
D. Flexor digitorum superficialis
B. Flexor digitorum profundus
Rationale: The flexor digitorum profundus muscle is responsible for flexing the distal interphalangeal (DIP) joints. The inability to flex the DIP joint while being able to flex the proximal interphalangeal (PIP) joint suggests an injury to the flexor digitorum profundus.
Overdistension of the valves of the atrioventricular orifices of the heart is prevented by the papillary muscles and which structure?
A. Ligamentum teres
B. Crista terminalis
C. Trabeculae carneae
D. Chordae tendineae
D. Chordae tendineae
Rationale: The chordae tendineae are tendinous cords that connect the papillary muscles to the atrioventricular valves, preventing valve prolapse during ventricular contraction.
The cerebellar cortex has three functional areas. The cortex of the vermis influences movements of the _____.
A. Distal parts of the body
B. Axial parts of the body
C. Lateral parts of the body
D. Proximal parts of the body
B. Axial parts of the body
Rationale: The cortex of the vermis is involved in controlling movements of the axial parts of the body, such as the trunk and proximal limbs.
Summary:
- Lateral Zone: Involved in planning and coordinating complex, sequential movements and conscious error correction.
- Vermis: Controls trunk muscles, maintains posture, and coordinates movements for axial equilibrium.
- Flocculonodular Lobe: Manages balance, eye movements, and body coordination based on vestibular input.
The common bile duct, hepatic artery, and portal vein are found grouped together in the:
A. Gastrocolic ligament
B. Hepatoduodenal ligament
C. Gastrosplenic ligament
D. Gastrohepatic ligament
B. Hepatoduodenal ligament
Rationale: The hepatoduodenal ligament contains the common bile duct, hepatic artery, and portal vein and forms part of the lesser omentum.
During micturition, nerve impulses cause contraction of this muscle:
A. Detrusor
B. Internal urethral sphincter
C. External urethral sphincter
D. Urethra
A. Detrusor
Rationale: During micturition, the detrusor muscle of the bladder contracts to expel urine.
In a displaced fracture of the patella, the superior fragment is displaced because of which muscle?
A. Semimembranosus
B. Quadriceps femoris
C. Gastrocnemius
D. Tibialis anterior
B. Quadriceps femoris
Rationale: The quadriceps femoris muscle attaches to the superior part of the patella via the quadriceps tendon. When the patella fractures, the superior fragment is pulled upward by the quadriceps femoris muscle.
Which of the following DOES NOT cross the pelvic brim?
A. Uterine artery
B. Ureter
C. Vas deferens
D. Internal iliac artery
A. Uterine artery:
The uterine artery, a branch of the internal iliac artery, does not cross the pelvic brim. It primarily supplies blood to the uterus and travels within the pelvis.
Most of the small intestine receives its blood supply from branches of a single artery. The artery that supplies most of the small bowel is the:
A. Superior mesenteric
B. Inferior mesenteric
C. Middle colic
D. Celiac
A. Superior mesenteric
Rationale: The superior mesenteric artery supplies blood to most of the small intestine, including the jejunum and ileum.
Which of the following tracts conveys pain and temperature sensations?
A. Dorsal Spinocerebellar tract
B. Lateral Spinothalamic tract
C. Lateral Reticulospinal tract
D. Dorsal column-medial lemniscus pathway
B. Lateral Spinothalamic tract
Rationale: The lateral spinothalamic tract conveys pain and temperature sensations from the body to the brain.
During the early stages of tuberculosis infections, the costal parietal pleura becomes inflamed and results in pain at the involved area. What nerve carries these painful sensations?
A. Phrenic nerve
B. Recurrent laryngeal nerve
C. Intercostal nerve
D. Vagus nerve
C. Intercostal nerve
Rationale: The costal parietal pleura is innervated by the intercostal nerves, which carry pain sensations when this pleura becomes inflamed.
This structure divides the dorsal aspect of the tongue into oral and pharyngeal parts:
A. Circumvallate papilla
B. Foramen cecum
C. Sulcus terminalis
D. Fungiform papilla
E. Lingual frenulum
C. Sulcus terminalis
Rationale: The sulcus terminalis is a V-shaped groove on the dorsal surface of the tongue that divides the anterior (oral) two-thirds from the posterior (pharyngeal) one-third.
A blood clot found in the left pulmonary artery probably came from which of the following?
A. Left atrium
B. Left brachiocephalic vein
C. Pulmonary veins
D. Right ventricle
D. Right ventricle
Rationale: A blood clot in the left pulmonary artery most likely originated from the right ventricle, as blood flows from the right ventricle into the pulmonary arteries.
Which of the following skull sutures join the frontal to the parietal bones?
A. Sagittal
B. Lambdoid
C. Zygomaticotemporal
D. Coronal
E. Sphenofrontal
D. Coronal
Rationale: The coronal suture joins the frontal bone to the parietal bones.
Which of the following muscles divide the neck into an anterior and a posterior triangle?
A. Levator scapulae
B. Trapezius
C. Digastric
D. Omohyoid
E. Sternocleidomastoid
E. Sternocleidomastoid
Rationale: The sternocleidomastoid muscle divides the neck into the anterior and posterior triangles.
Which of the following is the thickest component of the cornea?
A. Descemet’s membrane
B. Epithelium
C. Bowman’s membrane
D. Stroma
D. Stroma
Rationale: The stroma is the thickest layer of the cornea, consisting of regularly arranged collagen fibers.
The prostate gland lies:
A. At the neck of the bladder and above the pelvic diaphragm
B. Within the urogenital diaphragm
C. In the rectovesical space
D. In the superficial perineal space
A. At the neck of the bladder and above the pelvic diaphragm
Rationale: The prostate gland is located at the neck of the bladder and lies above the pelvic diaphragm.
What is the most medial among the following contents of the cubital fossa?
A. Median nerve
B. Biceps tendon
C. Brachial artery
D. Radial nerve
A. Median nerve
Rationale: The median nerve is the most medial structure within the cubital fossa.
Which of the following would most likely result from the reduction of Paneth cells?
A. Elevated undigested proteins
B. Decreased mucus in intestines
C. Thinning of the glycocalyx
D. Increase in intestinal bacteria
D. Increase in intestinal bacteria
Rationale: Paneth cells secrete antimicrobial peptides and enzymes, so a reduction in Paneth cells would likely result in an increase in intestinal bacteria.
What is an expected finding in the endometrium of a patient in the proliferative phase?
A. Small, straight, tubular glands
B. Small, inactive glands
C. Fragmented endometrium
D. Coiled to stellate glands
A. Small, straight, tubular glands
Rationale: During the proliferative phase of the menstrual cycle, the endometrium has small, straight, tubular glands as it regenerates and thickens under the influence of estrogen.
The central nervous system is derived from this germ layer:
A. Mesoderm
B. Ectoderm
C. Endoderm
D. Mesenchyme
B. Ectoderm
Rationale: The central nervous system is derived from the ectoderm germ layer.
Which artery is most commonly involved with massive posterior nasal cavity bleeds?
A. Greater palatine
B. Anterior ethmoid
C. Posterior ethmoid
D. Nasopalatine
E. Ascending palatine
A. Greater palatine
Rationale: Massive posterior nasal cavity bleeds are most commonly due to the sphenopalatine artery, which is a branch of the greater palatine artery. However, since “greater palatine” is the closest correct option, it is chosen.
Anterior Segment (Kiesselbach Plexus)
The Kiesselbach plexus is a common site for anterior nosebleeds and is located in the anterior part of the nasal septum. The arteries contributing to this plexus include:
* Superior Labial Artery: A branch of the facial artery.
* Anterior Ethmoidal Artery: A branch of the ophthalmic artery.
* Posterior Ethmoidal Artery: Also a branch of the ophthalmic artery.
* Greater Palatine Artery: A branch of the maxillary artery.
* Sphenopalatine Artery: A branch of the maxillary artery.
Posterior Segment
Life-threatening hemorrhages more commonly occur in the posterior segment of the nasal cavity and are usually associated with the sphenopalatine artery, which is a branch of the maxillary artery. The sphenopalatine artery supplies a significant portion of the posterior nasal cavity, making it a critical source of severe posterior nasal bleeds.
A patient presenting with an enlarged pupil and ptosis of the lid on the right side may have a lesion compressing the _____.
A. CN IV and VII
B. CN III and VII
C. CN III, V, VII
D. CN III, IV, VI
B. CN III and VII
CN III controls pupil constriction and eyelid elevation, while CN VII controls facial expressions. CN III involvement explains both the enlarged pupil and ptosis.
During a community rotation, a medical student was stung by a bee at the tip of his nose. The nerve responsible for the horrible sensation is:
A. CN V1 (ophthalmic branch)
B. CN V2 (maxillary branch)
C. CN V3 (mandibular branch)
D. CN VI (abducens nerve)
E. CN VII (facial nerve)
A. CN V1 (ophthalmic branch)
Rationale: The tip of the nose is innervated by the ophthalmic branch (V1) of the trigeminal nerve (CN V).
Cranial Nerve V (Trigeminal Nerve) Branches
The trigeminal nerve (CN V) is responsible for sensory innervation of the face and has three branches:
- CN V1 (Ophthalmic Branch): Provides sensory innervation to the forehead, scalp, upper eyelid, and the tip of the nose.
- CN V2 (Maxillary Branch): Provides sensory innervation to the lower eyelid, upper lip, cheek, and upper teeth.
- CN V3 (Mandibular Branch): Provides sensory innervation to the lower lip, lower teeth, chin, and jaw. It also has motor functions for mastication.
Cranial nerve/s found in between the olive and pyramid:
A. Hypoglossal nerve
B. Spinal Accessory nerve
C. Glossopharyngeal nerve
D. Vagus nerve
E. CN IX, X, XI
A. Hypoglossal nerve
Rationale: The hypoglossal nerve (CN XII) emerges between the olive and pyramid of the medulla.
The heart is located in which anatomical subdivision of the mediastinum?
A. Posterior
B. Middle
C. Anterior
D. Superior
B. Middle
Rationale: The heart is located in the middle mediastinum, which also contains the pericardium, roots of the great vessels, and other structures.
The final control of the parasympathetic system is in the _____.
A. Suprachiasmatic nucleus
B. Supra-optic nucleus
C. Pre-optic and anterior nuclei of the hypothalamus
D. Medial hypothalamic nucleus
C. Pre-optic and anterior nuclei of the hypothalamus
Rationale: The pre-optic and anterior nuclei of the hypothalamus play a crucial role in the control of the parasympathetic nervous system.
What is the most powerful flexor of the elbow?
A. Brachioradialis
B. Coracobrachialis
C. Brachialis
D. Biceps femoris
C. Brachialis
Rationale: The brachialis muscle is the most powerful flexor of the elbow because it directly acts on the ulna.
Which of the following nerves innervate the superior oblique muscle of the eye?
A. Oculomotor
B. Trochlear
C. Trigeminal
D. Abducens
E. Facial
B. Trochlear
Rationale: The trochlear nerve (CN IV) innervates the superior oblique muscle of the eye.
LR6 SO4 R3
Lesions that interrupt the visual pathway at the optic chiasm like pituitary tumors cause _____.
A. Superior quadrantanopsia
B. Complete blindness of one eye
C. Homonymous hemianopsia
D. Bilateral hemianopsia
D. Bilateral hemianopsia
Rationale: Lesions at the optic chiasm, such as those caused by pituitary tumors, typically result in bitemporal hemianopsia, which is the loss of vision in the outer (temporal) halves of the visual field in both eyes.
Which muscle is innervated by the ulnar nerve?
A. Flexor pollicis brevis
B. Opponens pollicis
C. Lumbrical 1
D. Adductor pollicis
D. Adductor pollicis
Rationale: The adductor pollicis muscle is innervated by the ulnar nerve. The other muscles listed are innervated by the median nerve.
The afferent pathway for the corneal reflex is:
A. CN V
B. CN IV
C. CN III
D. CN VII
A. CN V
Rationale: The afferent pathway for the corneal reflex is via the ophthalmic branch of the trigeminal nerve (CN V).
Afferent and Efferent Pathways of Each Reflex
-
Vestibulo-Ocular Reflex (VOR)
- Reflex Center: Vestibular nuclei in the brainstem.
- Afferent Pathway:
- Receptors: Hair cells in the semicircular canals of the inner ear detect head movements.
- Sensory Nerve: Vestibular nerve (part of the vestibulocochlear nerve, CN VIII) carries the signal to the vestibular nuclei.
- Efferent Pathway:
- Motor Nerve: Signals from the vestibular nuclei are sent to the nuclei of cranial nerves that control eye muscles (oculomotor nerve CN III, trochlear nerve CN IV, and abducens nerve CN VI).
- Effectors: Extraocular muscles adjust eye position to stabilize gaze. -
Pupillary Light Reflex
- Reflex Center: Pretectal area and Edinger-Westphal nucleus in the midbrain.
- Afferent Pathway:
- Receptors: Photoreceptors (rods and cones) in the retina detect light.
- Sensory Nerve: Optic nerve (CN II) carries the signal to the pretectal area.
- Efferent Pathway:
- Motor Nerve: From the pretectal area, signals are sent bilaterally to the Edinger-Westphal nuclei. From there, parasympathetic fibers travel with the oculomotor nerve (CN III) to the ciliary ganglion.
- Effectors: Postganglionic parasympathetic fibers innervate the sphincter pupillae muscles, causing pupil constriction. -
Corneal Reflex (Blink Reflex)
- Reflex Center: Trigeminal sensory nucleus and facial motor nucleus in the brainstem.
- Afferent Pathway:
- Receptors: Free nerve endings in the cornea detect mechanical stimulation.
- Sensory Nerve: Ophthalmic branch of the trigeminal nerve (CN V1) carries the signal to the trigeminal sensory nucleus.
- Efferent Pathway:
- Motor Nerve: Interneurons in the brainstem activate the facial motor nucleus. The facial nerve (CN VII) carries the signal to the orbicularis oculi muscle.
- Effectors: Orbicularis oculi muscle contracts, causing blinking. -
Gag Reflex (Pharyngeal Reflex)
- Reflex Center: Nucleus ambiguus and solitary nucleus in the medulla.
- Afferent Pathway:
- Receptors: Sensory receptors in the posterior pharynx and soft palate detect mechanical stimulation.
- Sensory Nerve: Glossopharyngeal nerve (CN IX) carries the signal to the solitary nucleus.
- Efferent Pathway:
- Motor Nerve: Signals are sent from the nucleus ambiguus via the vagus nerve (CN X) to the pharyngeal muscles.
- Effectors: Pharyngeal muscles contract, leading to the gagging response.
The main superficial draining vein of the fronto-parietal lobe is the _____.
A. Inferior sagittal sinus
B. Vein of Labbe
C. Vein of Galen
D. Vein of Rolando
D. Vein of Rolando
Rationale: The vein of Rolando, also known as the central sulcus vein, is the main superficial draining vein of the fronto-parietal lobe.
This structure is a cell station to all the main sensory systems EXCEPT the olfactory. This is the:
A. Basal ganglia
B. Thalamus
C. Somesthetic cortex
D. Caudate nucleus
B. Thalamus
Rationale: The thalamus acts as a relay station for sensory information to the cerebral cortex, except for the olfactory system, which bypasses the thalamus.
Hemisection of the spinal cord will have the following clinical findings, EXCEPT:
A. Ipsilateral weakness
B. Contralateral loss of joint position and vibration
C. Ipsilateral loss of joint position and vibration
D. Contralateral loss of pain and temperature
B. Contralateral loss of joint position and vibration
Rationale: Hemisection of the spinal cord (Brown-Séquard syndrome) typically results in ipsilateral loss of joint position and vibration sense, ipsilateral weakness, and contralateral loss of pain and temperature sensation.
Contralateral Lesions (The Rest Ipsilateral):
1. Motor Pathway (Corticospinal Tract):
- Effect: Paresis (weakness)
- Lesion Location: Contralateral to the site of the lesion.
2. DC/ML (Dorsal Column/Medial Lemniscus):
- Effect: Loss of proprioception and vibration sense.
- Lesion Location: Contralateral to the site of the lesion.
3. Spinothalamic Tract:
- Effect: Loss of pain and temperature sensation (PaTe)
- Lesion Location: Contralateral to the site of the lesion.
- Mnemonic: S PagheTTi (highlighting Pain and Temp)
Explanation:
- Contralateral Lesions:
- The pathways that cross to the opposite side (decussate) before reaching their targets result in contralateral effects when damaged.
- Motor Pathway (Corticospinal Tract): Originates in the cortex, crosses at the medulla (pyramidal decussation), affecting the opposite side of the body.
- DC/ML: Sensory pathways for proprioception and vibration cross in the medulla, affecting the opposite side.
- Spinothalamic Tract: Carries pain and temperature sensation, crosses at the spinal cord level, affecting the opposite side.
Which of the following pharyngeal muscles is innervated by the Glossopharyngeal nerve (CN IX)?
A. Superior constrictor
B. Middle constrictor
C. Inferior constrictor
D. Palatopharyngeus
E. Stylopharyngeus
E. Stylopharyngeus
Rationale: The stylopharyngeus muscle is innervated by the glossopharyngeal nerve (CN IX). The other pharyngeal muscles listed are innervated by the vagus nerve (CN X).
An injury to the posterior wall of the axilla will most likely affect which structure?
A. Pectoralis minor
B. Subscapularis
C. Long head of the biceps
D. Serratus anterior
B. Subscapularis
Rationale: The subscapularis muscle forms a major part of the posterior wall of the axilla. Injury to this area is likely to affect the subscapularis.
The main blood supply to the brain arises from the _____.
A. Innominate artery
B. Middle, anterior, and posterior cerebral arteries
C. Carotid and vertebral arteries
D. Circle of Willis
C. Carotid and vertebral arteries
Rationale: The main blood supply to the brain comes from the carotid and vertebral arteries, which form the Circle of Willis.
The facial nerve winds around the abducens nucleus producing the facial colliculus at the level of caudal pons.
A. False
B. True
B. True
Rationale: The facial nerve (CN VII) winds around the abducens nucleus (CN VI) to form the facial colliculus in the floor of the fourth ventricle at the level of the caudal pons.
The cerebral hemispheres are separated by a cleft which is occupied by a double fold of dura known as the _____.
A. Inferior sagittal sinus
B. Superior sagittal sinus
C. Falx cerebri
D. Tentorium
C. Falx cerebri
Rationale: The falx cerebri is a sickle-shaped fold of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres.
Summary
* The dura mater is the tough outer layer that forms protective folds (falx cerebri and tentorium cerebelli) to stabilize the brain within the skull.
* The arachnoid mater is a delicate middle layer involved in cushioning the brain and circulating CSF.
* The pia mater is the innermost layer that directly covers the brain and spinal cord, providing essential nutrients through its rich blood supply.
The cerebellum receives information from the cerebral cortex, muscles, tendons, joints, vestibular nuclei, and cortico-bulbar tracts. All information is fed into the cerebellar circuitry by the _____.
A. Intrinsic fibers
B. Efferent fibers
C. Mossy and climbing fibers
D. Arbor vitae
C. Mossy and climbing fibers
Rationale: Mossy and climbing fibers are the primary afferent inputs to the cerebellum, carrying information from various sources.
