MBBS First Year Human Anatomy - Section A MCQs (SET B)

Q1. Which of the following is an example of a pivot synovial joint?

• Atlanto-axial joint = pivot (rotation of head "No" movement)
• Atlanto-occipital = condyloid joint (flexion/extension "Yes" movement)
• Superior radioulnar = also a pivot joint
• Shoulder = ball and socket; First carpometacarpal = saddle

If the option reads "Atlanto-axial" (common printing), answer is (B). If the paper truly says "Atlanto-occipital," then (C) Superior radioulnar joint is the correct pivot joint. The superior radioulnar joint is a classic pivot joint example in anatomy exams.

Q2. Which of the following structures is NOT enclosed within a synovial joint capsule?

• Articular cartilage, synovial membrane, and synovial fluid are all within/part of a synovial joint
• Periosteum does NOT cover articular (hyaline) cartilage - it stops at the joint margins

Q3. The nerve most commonly injured in fracture of the surgical neck of the humerus is:

• The axillary nerve wraps around the surgical neck of the humerus - this is the classically injured nerve
• Wait - let me be precise: the axillary nerve (not radial) is the nerve at surgical neck
• The radial nerve is injured at the midshaft (radial groove / spiral groove) in "Holstein-Lewis" fractures

Correct answer: (C) Axillary nerve - the axillary nerve winds around the surgical neck of the humerus. The radial nerve is injured at the shaft (radial groove). This is a classic anatomy distinction.

Q4. The chief abductor of the arm between 15° and 90° is:

• Actually: Deltoid is the main abductor from 15-90°; Supraspinatus initiates abduction (0-15°)
• Correct: (A) Deltoid abducts 15°-90°; Supraspinatus initiates 0-15°

Q5. Which artery accompanies the radial nerve in the radial groove?

• The profunda brachii (deep brachial) artery accompanies the radial nerve as they spiral together in the radial groove (spiral groove) of the humerus
• Answer: (B) Deep brachial artery = profunda brachii

Q6. The tendon of which muscle forms the lateral boundary of the anatomical snuff box?

• Lateral (radial) boundary: tendons of Extensor pollicis brevis and Abductor pollicis longus
• Medial boundary: Extensor pollicis longus
• Floor: Scaphoid and trapezium

The answer marked in the paper appears to be (C) Abductor pollicis longus - correct, as it forms the lateral boundary along with extensor pollicis brevis.

Q7. Injury to the median nerve at the elbow most commonly causes weakness of:

• Median nerve at elbow/proximal forearm: supplies FPL (flexor pollicis longus), FDS, lateral FDP
• Loss = cannot flex thumb IP joint (FPL paralysis)
• "Ape hand" and "Hand of benediction" deformity
• Flexion of thumb via FPL is the classic answer

Q8. The strongest ligament of the shoulder joint is:

• The coracohumeral ligament is the strongest ligament of the shoulder (glenohumeral) joint
• It runs from the coracoid process to the greater tubercle of humerus
• It primarily resists inferior dislocation and external rotation

Q9. Cleavage of the zygote normally begins:

• Fertilization occurs in the ampulla of the uterine tube
• Cleavage (mitotic divisions) begins immediately during passage through the uterine tube
• The morula/early blastocyst reaches the uterus ~3-4 days after fertilization

Q10. The primitive streak first appears during:

• Primitive streak appears at the beginning of the 3rd week (day 15-16), marking the start of gastrulation

Correct answer: (C) Third week - the primitive streak is a defining feature of week 3 of embryonic development, initiating gastrulation.

Q11. Which type of epithelium is specialized for rapid diffusion of gases?

• Simple squamous epithelium is extremely thin - ideal for rapid diffusion
• Found in alveoli (Type I pneumocytes), capillary walls, Bowman's capsule
• Classic answer for gas exchange epithelium

Q12. Which epithelial tissue lines the urinary bladder?

• The urinary bladder is lined by transitional epithelium (urothelium)
• This specialized epithelium can stretch and recoil as the bladder fills and empties

Q13. The foramen transmitting the mandibular division of the trigeminal nerve is:

• CN V3 (mandibular division) exits through foramen ovale
• CN V1 (ophthalmic): superior orbital fissure
• CN V2 (maxillary): foramen rotundum
• CN V3 (mandibular): foramen ovale

Note: The paper marks option (A) as Foramen rotundum - that is for V2. The correct answer for mandibular (V3) is Foramen ovale = (C).

Q14. The parotid duct pierces the:

• Stensen's duct (parotid duct) runs forward from the parotid gland, crosses the masseter, turns medially, and pierces the buccinator muscle to open into the oral cavity opposite the upper 2nd molar

Q15. The carotid sinus is located at the:

• The carotid sinus is a dilation at the bifurcation of the common carotid artery (origin of internal carotid)
• It is a baroreceptor sensitive to blood pressure changes

Q16. The cerebrospinal fluid is mainly produced by the:

• CSF is produced mainly by the choroid plexus (especially in the lateral ventricles)
• Arachnoid villi are where CSF is reabsorbed into venous sinuses

Q17. The internal capsule is supplied mainly by:

• The internal capsule is supplied by lenticulostriate arteries (also called "arteries of stroke"), branches of the middle cerebral artery
• These are end arteries - rupture causes classic internal capsule strokes

Q18. Myelin in the central nervous system is produced by:

• Oligodendrocytes produce myelin in the CNS
• Schwann cells produce myelin in the PNS
• Astrocytes = structural support; Microglia = CNS macrophages

Q19. The thyroid gland follicles are lined by:

• Thyroid follicles are lined by simple cuboidal epithelium (follicular cells/thyrocytes)
• The epithelium becomes columnar when the gland is active and squamous when inactive

Q20. The thyroid gland develops primarily from:

• The thyroid gland develops from an endodermal thickening in the floor of the primitive pharynx (foramen cecum region, between the 1st and 2nd pharyngeal arches)
• It descends via the thyroglossal duct to its final position
• The C-cells (parafollicular) come from neural crest cells (4th pharyngeal pouch)

Summary Table

• Surgical neck humerus = Axillary nerve; Radial groove (midshaft) = Radial nerve
• CSF produced by choroid plexus; absorbed by arachnoid villi
• CNS myelin = oligodendrocytes; PNS myelin = Schwann cells
• Foramen ovale = V3 (mandibular); Foramen rotundum = V2 (maxillary)
• Pivot joints: Atlanto-axial, superior & inferior radioulnar