79)
c. Simple columnar with brush border
• Gallbladder is lined by the columnar epithelium with brush border (irregularly placed microvilli).

80) Explanation


• Periosteum has dense but no definite orientation (irregular) of collagen fibers. Tendon, aponeurosis and ligaments have collagen fiber bundles which are arranged in a uniform parallel (regular) fashion.

81) Explanation

• Ulnar nerve passes above (superficial) to flexor retinaculum especially the palmar cutaneous branch of ulnar nerve

82) Explanation

• Labia majora is homologous to scrotum in male.
• Round ligament terminates at upper border of labia majora

82) Explanation

• Labia majora is homologous to scrotum in male.
• Round ligament terminates at upper border of labia majora

83) Explanation


• The anatomical snuffbox is formed by the tendons of extensor polloicis longus and brevis, and abductor pollicis longus.
• It has the radial artery running in the floor of the snuffbox, and the radial nerve passing to the dorsum of the hand.
• Boundaries of snuff box:
ƒ Postero-medial border is the tendon of the extensor pollicis longus.
ƒ Antero-lateral border is a pair of parallel and intimate tendons of the extensor pollicis brevis and the abductor pollicis longus.
ƒ The proximal border is formed by the styloid process of the radius.
ƒ The distal border is formed by the approximate apex of the schematic snuffbox isosceles

83) Explanation


• The anatomical snuffbox is formed by the tendons of extensor polloicis longus and brevis, and abductor pollicis longus.
• It has the radial artery running in the floor of the snuffbox, and the radial nerve passing to the dorsum of the hand.
• Boundaries of snuff box:
ƒ Postero-medial border is the tendon of the extensor pollicis longus.
ƒ Antero-lateral border is a pair of parallel and intimate tendons of the extensor pollicis brevis and the abductor pollicis longus.
ƒ The proximal border is formed by the styloid process of the radius.
ƒ The distal border is formed by the approximate apex of the schematic snuffbox isosceles

84) Ans. (a) Metencephalon

Explanation

Myelencephalon Medulla oblongata
Metencephalon Pons, cerebellum and 4th ventricle
Mesencephalon Midbrain and aqueduct of slyvius
Diencephalon Thalamus, hypothalamus and 3rd ventricle
Telencephalon Cerebral hemispheres and lateral ventricles

85) Explanation



• Anterior shoulder dislocation can cause injury to axillary nerve
• Axillary nerve passes inferior to the humeral head and winds around the surgical neck of the humerus. The axillary nerve is usually injured during fracture of this part of the humerus.
• It may also be damaged during dislocation of the gleno humeral joint and by compression from the incorrect use of crutches

86) Explanation


• Median nerve is the main nerve of the front of the forearm. It also supplies the muscles of thenar eminence.
• The ape hand deformity or ape thumb deformity of hand is due to paralysis of thenar muscles which is supplied by median nerve.

Presenting Feature of Ape Thumb Deformity
• Thumb is laterally rotated and adducted
• Loss of thenar eminence
• Loss of opposition of thumb

87) Explanation




• As the amniotic cavity enlarges, it obliterates the chorionic cavity and covers the connecting stalk and gets reflected at the region of primitive umbilical ring (amino-ectodermal junction).

• The primitive umbilical region gradually gets crowded and contains:
(i) connecting stalk having allantois, umbilical vessels (two arteries and one vein),
(ii) yolk stalk (vitelline duct) along with vitelline vessels, and
(iii) the canal connecting the intraembryonic and extraembryonic cavities.

• All these structures finally give rise to primitive umbilical cord. A part of the yolk sac which lies in the chorionic cavity later shrinks and gets obliterated.
• Initially when the abdominal cavity is too small, and the loops of intestine grow very fast, some of them get pushed into the extraembryonic space in the umbilical cord. This is called physiological umbilical hernia.
• By the end of the third month, the abdominal cavity enlarges and the loop of intestine returns into the abdomen and the extraembryonic cavity of umbilical cord gets obliterated.
• The structures of the umbilical cord, i.e., vitelline duct, vitelline vessels and allantois also get obliterated and are converted into Wharton’s jelly. The only structures which remain functional in Wharton’s jelly are the umbilical vessels.