ANATOMY (2024) - PART 2

Question 1

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

Answer 1

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).

Question 2

The following bones make up the orbit, EXCEPT:
A. Ethmoid
B. Sphenoid
C. Frontal
D. Nasal
E. Lacrimal

Answer 2

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.

Question 3

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

Answer 3

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.

Question 4

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

Answer 4

D. Scala tympani
Rationale: Perilymph is found in the scala tympani and scala vestibuli of the cochlea. The scala media contains endolymph.

Histology

Question 5

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

Answer 5

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.

Question 6

Which vertebral region has bifid spinous processes?
A. Sacral
B. Thoracic
C. Lumbar
D. Cervical

Answer 6

D. Cervical
Rationale: The cervical vertebrae, particularly C2 to C6, have bifid spinous processes.

Question 7

Which structure is found deep to the flexor retinaculum?
A. Flexor carpi radialis
B. Ulnar nerve
C. Flexor digitorum profundus
D. Palmaris longus

Answer 7

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.

Question 8

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

Answer 8

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).

Question 9

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

Answer 9

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.

Question 10

Neuronal degeneration of the basal ganglia is the cause of this disease.
A. Quadriparesis
B. Diplegia
C. Parkinson’s disease
D. Hemiplegia

Answer 10

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.

Question 11

Which of the following nerves passes through the superficial inguinal ring?
A. Iliohypogastric nerve
B. Obturator nerve
C. Pudendal nerve
D. Ilioinguinal nerve

Answer 11

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.

Question 12

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

Answer 12

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
• Left Kidney in Transplantation:
  
  • The left kidney is often taken during living donor transplantation because it has a longer renal vein.and capillaries.

Question 13

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

Answer 13

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.

Question 14

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

Answer 14

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.

Question 15

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

Answer 15

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.

Question 16

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

Answer 16

D. Plane of the sternal angle
Rationale: The trachea bifurcates at the level of the sternal angle (T4/T5 vertebral level).

Question 17

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

Answer 17

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.

Question 18

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

Answer 18

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.

Question 19

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)

Answer 19

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.

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.

Question 20

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

Answer 20

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.

Question 21

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

Answer 21

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.

Question 22

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

Answer 22

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.

Question 23

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

Answer 23

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.

Question 24

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

Answer 24

B. Hepatoduodenal ligament
Rationale: The hepatoduodenal ligament contains the common bile duct, hepatic artery, and portal vein and forms part of the lesser omentum.

Question 25

During micturition, nerve impulses cause contraction of this muscle: A. Detrusor B. Internal urethral sphincter C. External urethral sphincter D. Urethra

Answer 25

A. Detrusor Rationale: During micturition, the detrusor muscle of the bladder contracts to expel urine.

Question 26

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

Answer 26

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.

Question 27

Which of the following DOES NOT cross the pelvic brim? A. Uterine artery B. Ureter C. Vas deferens D. Internal iliac artery

Answer 27

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.

Question 28

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

Answer 28

A. Superior mesenteric Rationale: The superior mesenteric artery supplies blood to most of the small intestine, including the jejunum and ileum.

Question 29

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

Answer 29

B. Lateral Spinothalamic tract Rationale: The lateral spinothalamic tract conveys pain and temperature sensations from the body to the brain.

Question 30

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

Answer 30

C. Intercostal nerve Rationale: The costal parietal pleura is innervated by the intercostal nerves, which carry pain sensations when this pleura becomes inflamed.

Question 31

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

Answer 31

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.

Question 32

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

Answer 32

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.

Question 33

Which of the following skull sutures join the frontal to the parietal bones? A. Sagittal B. Lambdoid C. Zygomaticotemporal D. Coronal E. Sphenofrontal

Answer 33

D. Coronal Rationale: The coronal suture joins the frontal bone to the parietal bones.

Question 34

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

Answer 34

E. Sternocleidomastoid Rationale: The sternocleidomastoid muscle divides the neck into the anterior and posterior triangles.

Question 35

Which of the following is the thickest component of the cornea? A. Descemet’s membrane B. Epithelium C. Bowman’s membrane D. Stroma

Answer 35

D. Stroma Rationale: The stroma is the thickest layer of the cornea, consisting of regularly arranged collagen fibers.

Question 36

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

Answer 36

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.

Question 37

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

Answer 37

A. Median nerve Rationale: The median nerve is the most medial structure within the cubital fossa.

Question 38

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

Answer 38

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.

Question 39

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

Answer 39

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.

Question 40

The central nervous system is derived from this germ layer: A. Mesoderm B. Ectoderm C. Endoderm D. Mesenchyme

Answer 40

B. Ectoderm Rationale: The central nervous system is derived from the ectoderm germ layer.

Question 41

Which structure is a key landmark for the passage of vessels in the gluteal region? A. Quadratus femoris B. Pyriformis C. Gluteus medius D. Gluteus maximus

Answer 41

B. Pyriformis Rationale: The piriformis muscle is a key landmark in the gluteal region because the superior and inferior gluteal vessels and nerves pass above and below it, respectively.

Question 42

Which group of structures empties directly into the right atrium? A. Coronary sinus and azygos vein B. Superior vena cava, coronary sinus, and hemiazygos vein C. Superior and inferior venae cavae and coronary sinus D. Coronary sinus and pulmonary vein

Answer 42

C. Superior and inferior venae cavae and coronary sinus Rationale: The superior vena cava, inferior vena cava, and coronary sinus all empty directly into the right atrium of the heart.

Question 43

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

Answer 43

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.

Question 44

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

Answer 44

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.

Question 45

It supplies the tubular portions of the nephron in the renal medulla: A. Vasa recta B. Peritubular capillaries C. Arcuate arteries D. Segmental arteries

Answer 45

A. Vasa recta Rationale: The vasa recta are long, straight capillaries that supply the tubular portions of the nephron in the renal medulla.

Question 46

The Stensen's duct opens opposite to the: A. Lower 2nd premolar tooth B. Upper 1st premolar tooth C. Upper 2nd molar tooth D. Lower 2nd molar tooth E. Base of tongue

Answer 46

C. Upper 2nd molar tooth Rationale: Stensen's duct, also known as the parotid duct, opens opposite the upper second molar tooth.

Question 47

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)

Answer 47

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: 1. CN V1 (Ophthalmic Branch): Provides sensory innervation to the forehead, scalp, upper eyelid, and the tip of the nose. 2. CN V2 (Maxillary Branch): Provides sensory innervation to the lower eyelid, upper lip, cheek, and upper teeth. 3. CN V3 (Mandibular Branch): Provides sensory innervation to the lower lip, lower teeth, chin, and jaw. It also has motor functions for mastication.

Question 48

Which lymphoid organ actively recycles Iron and Heme? A. Spleen B. Thymus C. Bone Marrow D. Lymph Nodes

Answer 48

A. Spleen Rationale: The spleen is responsible for filtering the blood, recycling iron and heme from old red blood cells.

Question 49

In a complete, displaced fracture of the right clavicle, the medial fragment is displaced superiorly because of which muscle? A. Subclavius B. Pectoralis major C. Biceps long head D. Sternocleidomastoid

Answer 49

D. Sternocleidomastoid Rationale: The sternocleidomastoid muscle pulls the medial fragment of the clavicle superiorly in the event of a fracture.

Question 50

During diastole, the aortic valve: A. Prevents reflux of blood into the left ventricle B. Prevents reflux of blood into the left atrium C. Prevents reflux of blood into the right ventricle D. Prevents reflux of blood into the right atrium

Answer 50

A. Prevents reflux of blood into the left ventricle Rationale: During diastole, the aortic valve closes to prevent blood from flowing back into the left ventricle from the aorta.

Question 51

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

Answer 51

A. Hypoglossal nerve Rationale: The hypoglossal nerve (CN XII) emerges between the olive and pyramid of the medulla.

Question 52

The heart is located in which anatomical subdivision of the mediastinum? A. Posterior B. Middle C. Anterior D. Superior

Answer 52

B. Middle Rationale: The heart is located in the middle mediastinum, which also contains the pericardium, roots of the great vessels, and other structures.

Question 53

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

Answer 53

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.

Question 54

What is the most powerful flexor of the elbow? A. Brachioradialis B. Coracobrachialis C. Brachialis D. Biceps femoris

Answer 54

C. Brachialis Rationale: The brachialis muscle is the most powerful flexor of the elbow because it directly acts on the ulna.

Question 55

Which of the following nerves innervate the superior oblique muscle of the eye? A. Oculomotor B. Trochlear C. Trigeminal D. Abducens E. Facial

Answer 55

B. Trochlear Rationale: The trochlear nerve (CN IV) innervates the superior oblique muscle of the eye. LR6 SO4 R3

Question 56

The following are blood supplies of the thyroid gland, EXCEPT: A. Superior thyroid artery B. Middle thyroid artery C. Inferior thyroid artery D. Thyroidea ima artery E. None of the above

Answer 56

B. Middle thyroid artery Rationale: There is no middle thyroid artery. The thyroid gland is supplied by the superior thyroid artery, inferior thyroid artery, and sometimes the thyroidea ima artery.

Question 57

This structure separates the middle from the external ear: A. Auricle B. Eustachian tube C. Promontory D. Tympanic membrane E. Oval window

Answer 57

D. Tympanic membrane Rationale: The tympanic membrane (eardrum) separates the external ear from the middle ear.

Question 58

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

Answer 58

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.

Question 59

Which muscle is innervated by the ulnar nerve? A. Flexor pollicis brevis B. Opponens pollicis C. Lumbrical 1 D. Adductor pollicis

Answer 59

D. Adductor pollicis Rationale: The adductor pollicis muscle is innervated by the ulnar nerve. The other muscles listed are innervated by the median nerve.

Question 60

A complete tear of the medial collateral ligament of the knee can be confirmed by which maneuver? A. Varus stress test B. Valgus stress test C. McMurray test D. Lachmann's test

Answer 60

B. Valgus stress test Rationale: The valgus stress test is used to assess the integrity of the medial collateral ligament (MCL) of the knee.

Question 61

The afferent pathway for the corneal reflex is: A. CN V B. CN IV C. CN III D. CN VII

Answer 61

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 1. **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. 2. **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. 3. **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. 4. **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.

Question 62

In the human kidney, the renal papilla projects directly into the: A. Renal columns B. Minor calyx C. Major calyx D. Renal pyramid

Answer 62

B. Minor calyx Rationale: The renal papilla projects directly into the minor calyx, which collects urine from the renal pyramids.

Question 63

Which of the following cells have a dense nucleus and are primarily affected in patients with hyperthyroidism? A. Oxyphil B. Parafollicular C. Principal D. Follicular

Answer 63

D. Follicular Rationale: Follicular cells in the thyroid gland are primarily affected in hyperthyroidism, as they produce thyroid hormones (T3 and T4).

Question 64

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

Answer 64

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.

Question 65

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

Answer 65

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.

Question 66

Which of the following statements is TRUE regarding the ureters? A. The proximal two-thirds of the ureters are retroperitoneal while its distal third is intraperitoneal. B. As the urinary bladder fills with urine, pressure within compresses the oblique anatomical valve at the opening of each ureter which prevents the backflow of urine. C. The ureters move urine via peristaltic action coming from the renal pelvis. D. At the base of the urinary bladder, the ureters curve medially and pass obliquely through the wall of the posterior aspect of the urinary bladder

Answer 66

C. The ureters move urine via peristaltic action coming from the renal pelvis. The ureters transport urine from the kidneys to the bladder using peristaltic waves generated by smooth muscle contractions in their walls. This peristaltic action begins at the renal pelvis and continues throughout the length of the ureter, ensuring a continuous flow of urine into the bladder

Question 67

Carcinomas are commonly found in which part of the stomach? A. Fundus B. Body C. Cardia D. Pylorus

Answer 67

D. Pylorus Rationale: Carcinomas of the stomach are most commonly found in the pyloric region.

Question 68

A board exam passer broke into tears as she learned of the good news. In seconds, she began experiencing watery nasal discharge. She quickly realized that her tears drained into her nasal cavity, specifically into this area: A. Supreme meatus B. Sphenoethmoidal recess C. Superior meatus D. Middle meatus E. Inferior meatus

Answer 68

E. Inferior meatus Rationale: Tears from the nasolacrimal duct drain into the inferior meatus of the nasal cavity.

Question 69

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

Answer 69

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.

Question 70

Which of the following cells are pyramidal in shape whose apical and basal ends adhere to the lumen and basal lamina of the seminiferous tubules respectively? A. Sustentacular B. Spermatogenic C. Leydig D. Interstitial

Answer 70

A. Sustentacular Rationale: Sustentacular cells, also known as Sertoli cells, are pyramidal in shape and provide structural and nutritional support to developing sperm cells within the seminiferous tubules.

Question 71

Which bone is found in the lateral longitudinal arch of the foot? A. Navicular B. 1st metatarsal C. Cuboid D. 2nd cuneiform

Answer 71

C. Cuboid Rationale: The lateral longitudinal arch of the foot is composed of the calcaneus, cuboid, and the fourth and fifth metatarsals. The cuboid is a key bone in this arch.

Question 72

Which apical modifications are present in the respiratory epithelium? A. Flagella B. Cilia C. Villi D. Stereocilia

Answer 72

B. Cilia Rationale: The respiratory epithelium is characterized by the presence of cilia, which help move mucus and trapped particles out of the respiratory tract.

Question 73

Increased resistance to pulmonary blood flow in the lungs would cause a direct strain on which chamber of the heart? A. Right atrium B. Right ventricle C. Left atrium D. Left ventricle

Answer 73

B. Right ventricle Rationale: Increased resistance to pulmonary blood flow causes increased workload on the right ventricle, as it pumps blood to the lungs.

Question 74

Flexion-extension of the ankle joint occurs at which joint? A. Calcaneo-cuboid B. Tibio-talar C. Talo-calcaneal D. Talo-navicular

Answer 74

B. Tibio-talar Rationale: Flexion (dorsiflexion) and extension (plantarflexion) of the ankle joint occur at the tibio-talar (talocrural) joint. Movements of the Ankle and Foot • Dorsiflexion and Plantar Flexion: • Type of Joint: These movements occur at the tibio-talar (talocrural) joint, which functions as a hinge joint. • Dorsiflexion: Upward movement of the foot towards the shin. • Plantar Flexion: Downward movement of the foot away from the shin. • Inversion and Eversion: • Type of Joints: These movements occur at the tarsal joints, particularly the subtalar (talo-calcaneal) and transverse tarsal (talonavicular and calcaneocuboid) joints. • Inversion: Turning the sole of the foot inward. • Eversion: Turning the sole of the foot outward.

Question 75

The superior and inferior gluteal arteries arise from the: A. Superior rectal artery B. Median sacral artery C. Common iliac artery D. Internal iliac artery

Answer 75

D. Internal iliac artery Rationale: The superior and inferior gluteal arteries are branches of the internal iliac artery.

Question 76

Which small, polygonal cells are most abundant in the central region of the islet of Langerhans of the pancreas and are most affected in patients with diabetes mellitus? A. Alpha B. Beta C. F D. Delta

Answer 76

B. Beta Rationale: Beta cells are the most abundant cells in the central region of the islets of Langerhans and are responsible for insulin production. These cells are most affected in diabetes mellitus.

Question 77

When foreign objects are aspirated into the trachea, they will usually pass into the right primary bronchus because: A. It is straighter, longer, and larger than the left B. It is larger, straighter, and shorter than the left C. It is at a 90-degree angle to the trachea D. It is more curved, longer, and smaller than the left

Answer 77

B. It is larger, straighter, and shorter than the left Rationale: The right primary bronchus is larger, more vertical, and shorter than the left, making it the more likely path for aspirated objects.

Question 78

This muscle divides the maxillary artery into 3 parts. A. Mentalis B. Medial pterygoid C. Lateral pterygoid D. Masseter E. Temporalis

Answer 78

C. Lateral pterygoid Rationale: The lateral pterygoid muscle divides the maxillary artery into three parts: the mandibular part, the pterygoid part, and the pterygopalatine part.

Question 79

Stimulation of the Vagus nerve will make the heart _____. A. Tachycardic B. Dysrhythmic C. Cause to have missed beats D. Bradycardic

Answer 79

D. Bradycardic Rationale: Stimulation of the vagus nerve decreases heart rate, causing bradycardia.

Question 80

Which nerve innervates the flexor compartment of the arm? A. Axillary B. Median C. Radial D. Musculocutaneous

Answer 80

D. Musculocutaneous Rationale: The musculocutaneous nerve innervates the muscles in the flexor compartment of the arm, including the biceps brachii, brachialis, and coracobrachialis muscles.

Question 81

Which is NOT a component of the Glomerular Filtration Barrier? A. Filtration Slit Diaphragm B. Fenestrated capillary endothelium C. Pedicels of Podocytes D. Glomerular Basement Membrane

Answer 81

C. Pedicels of Podocytes Rationale: The glomerular filtration barrier consists of the: -fenestrated capillary endothelium, -glomerular basement membrane, -filtration slit diaphragm. The pedicels of podocytes, while important for filtration, are part of the podocyte structure but not a direct component of the filtration barrier itself.

Question 82

What is the most common direction of dislocation of the gleno-humeral joint? A. Lateral B. Posterior C. Anterior D. Medial

Answer 82

C. Anterior Rationale: Anterior dislocation is the most common type of glenohumeral joint dislocation due to the anatomical weaknesses in the anterior capsule and the mechanics of typical shoulder movements.

Question 83

The roof of the ischiorectal fossa is formed by which of the following? A. Obturator fascia B. External anal sphincter C. Levator ani D. Obturator internus muscle

Answer 83

C. Levator ani Rationale: The roof of the ischiorectal (ischioanal) fossa is formed by the levator ani muscle, which is part of the pelvic diaphragm.

Question 84

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

Answer 84

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).

Question 85

The tooth component that covers the root is called: A. Dentin B. Crown C. Cementum D. Enamel E. Neck

Answer 85

C. Cementum Rationale: Cementum is the hard, calcified tissue that covers the roots of teeth, providing attachment for the periodontal ligament.

Question 86

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

Answer 86

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.

Question 87

Which of the following muscles produce the "grinding" movement of the mandible? A. Lateral pterygoid B. Medial pterygoid C. Masseter D. Temporalis E. Buccinator

Answer 87

A. Lateral pterygoid Rationale: The lateral pterygoid muscle is responsible for the grinding movement of the mandible by moving the jaw from side to side.

Question 88

The coronary vessels are found in which layer of the heart? A. Endocardium B. Subendocardium C. Myocardium D. Epicardium

Answer 88

D. Epicardium Rationale: The coronary vessels are found in the epicardium, which is the outer layer of the heart.

Question 89

What is the most lateral among the following contents of the femoral triangle? A. Femoral artery B. Femoral canal C. Femoral nerve D. Femoral vein

Answer 89

C. Femoral nerve Rationale: In the femoral triangle, the femoral nerve is the most lateral structure, followed by the femoral artery, femoral vein, and femoral canal.

Question 90

Which of the following structures is the primary organ for hearing? A. Cochlea B. Semicircular canals C. Auricle D. Utricle E. Saccule

Answer 90

A. Cochlea Rationale: The cochlea is the primary organ for hearing, containing the sensory receptors for sound.

Question 91

Which of the following cardiac veins empties directly into the right atrium of the heart? A. Anterior cardiac B. Middle cardiac C. Small cardiac D. Great cardiac

Answer 91

A. Anterior cardiac Rationale: The anterior cardiac veins empty directly into the right atrium, bypassing the coronary sinus.

Question 92

A positive posterior drawer's test implies injury to which structure? A. Anterior cruciate ligament B. Medial collateral ligament C. Lateral collateral ligament D. Posterior cruciate ligament

Answer 92

D. Posterior cruciate ligament Rationale: A positive posterior drawer test indicates a tear or injury to the posterior cruciate ligament (PCL).

Question 93

Which laryngeal structure is involved with voice production? A. Epiglottis B. Vocal fold C. Vestibular fold D. Ventricle E. Laryngeal prominence

Answer 93

B. Vocal fold Rationale: The vocal folds (vocal cords) are directly involved in voice production by vibrating as air passes through them.

Question 94

Which renal tubule is located in the renal cortex? A. Thick limb of loop of Henle B. Thin limb of loop of Henle C. Distal convoluted tubule D. Collecting duct

Answer 94

C. Distal convoluted tubule Rationale: The distal convoluted tubule is located in the renal cortex. The thick and thin limbs of the loop of Henle and the collecting ducts are primarily located in the medulla.

Question 95

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

Answer 95

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.

Question 96

The uterine tube runs in the free border of a double-layered sheet of peritoneum clothing the anterior and posterior surfaces of the uterus and attaching laterally to the pelvic wall. This sheet is known as the: A. Mesovarium B. Recto-uterine fold C. Suspensory ligament of the ovary D. Broad ligament

Answer 96

D. Broad ligament Rationale: The broad ligament is a double-layered sheet of peritoneum that supports the uterus, fallopian tubes, and ovaries, extending from the sides of the uterus to the walls and floor of the pelvis.

Question 97

The facial nerve winds around the abducens nucleus producing the facial colliculus at the level of caudal pons. A. False B. True

Answer 97

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.

Question 98

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

Answer 98

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.

Question 99

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

Answer 99

C. Mossy and climbing fibers Rationale: Mossy and climbing fibers are the primary afferent inputs to the cerebellum, carrying information from various sources.

Question 100

A patient who is unable to maintain his balance when assuming a one-legged stance most likely has weakness in which muscle? A. Quadriceps femoris B. Gluteus medius C. Semimembranosus D. Tensor fasciae latae

Answer 100

B. Gluteus medius Rationale: The gluteus medius muscle is crucial for maintaining balance and stability when standing on one leg. Weakness in this muscle can lead to difficulty maintaining balance in such a stance.