ANATOMY
MCQ’S 1
RxDENTISTRY
RX DENTISTRY PRESENTS YOU WITH
NEW MCQ’S SERIES . TO START WITH
HERE IS ANATOMY
Dr. MADAAN
2/18/2009
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1. The subodontoblastic plexus of Raschkow occurs:
a. Below the cell bodies of odontoblasts
b. In the root region of the pulp
c. Within the central pulp core
d. Within the cell-rich zone of Weil
2. Uppermost structure seen at the hilum of the left lung is:
a. Pulmonary artery b. Pulmonary vein
c. Bronchus d. Bronchial artery
3. Ulnar injury in the arm leads to all except:
a. Sensory loss of the medial 1/3rd of the hand
b. Weakness of the hypothenar muscles
c. Claw hand
d. adduction of thumb
4. Left renal vein crosses the Aorta:
a. Anteriorly, above the superior mesenteric artery
b. Anteriorly, below the superior mesenteric artery
c. Posteriorly, at the level of superior mesenteric artery
d. Anteriorly, below the inferior mesenteric artery
5. What are intrinsic fibers of cementum?
a. Fibers produced by cementoblasts
b. Noncalcified fibers associated with the attachment of
periodontal ligament fibers
c. Principal fibers of the PDL
d. None of the above
6. In post-ductal coarctation of the aorta, blood flow to the
lower limbs in maintained by increased blood flow
through:
a. Inferior Phrenic and pericardio phrenic vessels
b. Intercostal and Superior epigastric
c. Sub costal and Umbilical
d. Umbilical and superior gastric
7. Seen in agenesis of corpus callosum is:
a. Astereognosis b. Hemiparesis
c. Hemi sensory loss d. No neurological deficit
8. One of the following is the watershed area of the colon
between the superior and inferior mesenteric arteries:
a. Ascending colon b. Hepatic flexure
c. Splenic flexure d. Descending colon
9. Gall bladder epithelium is:
a. Simple squamous b. Simple cuboidal with stereocilia
c. Simple columnar d. Simple columnar with brush border
10. Perforating fibers consisting of collagen fibers
embedded in alveolar bone proper are known as:
a. Gingival fibers b. Sharpey’s fibers
c. Transseptal fibers d. Alveolar fibers
11. Which muscle is not punctured while doing a thoracic
procedure in the mid-axillary line:
a. Innermost intercostals b. Transverses thoracis
c. External intercostals d. Internal intercostals
12. Dangerous area of the eye is:
a. Ciliary body b. Sclera c. Optic nerve d. Retina
13. Urothelium does not line:
a. Collecting ducts b. Minor calyx
c. Ureter d. Urinary bladder
14. Which type of gingival fibers attaches to cementum of
adjacent teeth and is present over the alveolar crest?
a. Alveolar crest fibers b. Alveologingival fibers
c. Transseptal fibers d. Circular fibers
15. The secretory product of odontoblasts is:
a. Topocollagen. b. Calcium salts.
c. Mantle dentin. d. Hydroxyapatite.
16. The escapement spaces between teeth and the interdental
spaces are called:
a. Marginal ridges. b. Contact areas.
c. Embrasures. d. Developmental grooves
17. Basement membrane consists of all except:
a. Laminin b. Nidogenin
c. Entactin d. Rhodopsin
18. Perforators are not present at the:
a. Ankle b. Distal calf
c. Mid thigh d. Below the inguinal ligament
19. Tongue muscles develops from:
a. Occipital somites b. Mesoderm of the pharyngeal pouch
c. Cervical somites d. Endoderm of pharyngeal pouch
20. A female come with complaints of chest pain. On
examination she is found to have pericarditis with
pericardial effusion. The pain is mediated by:
a. Deep cardiac plexus b. Superficial cardiac plexus
c. Phrenic nerve d. Subcostal nerve
21. Meiosis occurs at which of the following transformation:
a. Primary spermatocyte to intermediate spermatocyte
b. Primary spermatocyte to secondary spermatocyte
c. Secondary spermatocyte to round spermatid
d. Round spermatid to elongated spermatid
22. The ureter develops from:
a. Metanephros b. Mesonephros
c. Mesonephric duct d. Paramesonephric duct
23. Inflammation of a retrocaecal appendix will produce
pain when there is which of the following movements at
the hip:
a. Flexion b. Extension
c. Medial rotation d. Lateral rotation
24. In Hyaline cartilage, type of collagen present is:
a. Type 1 b. Type 2 c. Type 3 d. Type 4
25. All of the following statements are true for metaphysis
of bone, except -
a. It is the strongest part of bone.
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b. It is the most vascular part of bone.
c. Growth activity50 is maximized here.
d. It is the region favoring hematogenous spread of
infection.
26. All of the following muscles are grouped together as
‘muscles of mastication’ except -
a. Buccinator. b.Masseter. c.Temporalis. d.Pterygoids.
27. In emergency tracheostomy the following structures are
damaged except:
a. Isthmus of the thyroid b. Inferior thyroid artery
c. Thyroidea ima d. Inferior thyroid vein
28. Vidian Nerve is formed by
a. Deep Petrosal & Greater Superficial Petrosal nerve
b. Greater Superficial Petrosal Nerve and Lesser
Superficial Petrosal Nerve.
c. Deep Petrosal Nerve and Lesser Superficial Petrosal
Nerve
d. None of the above
29. Kanavel’s sign is seen in:
a. Tenosynovitis b. Dupuyteren’s contracture
c. Carpal tunnel syndrome d. Trigger finger
30. Which of the following is correctly matched:
a. B cells – Somatostain b. D cells – Insulin
c. G cells – Gastrin d. A cells - renin
31. Internal spermatic fascia is derived from
a. Transversalis facia
b. Internal abdominis muscle
c. External Oblique Abdominis Muscle
d. Internal Oblique Abdominis Muscle
32. Sertoli cells in the testis have receptors for:
a. FSH b. LH c. Inhibin d. testosterone
33. External laryngeal nerve supplies
a. Superior Constrictor. b. Middle Constrictor.
c. Inferior constrictor. d. None of the above
34. Most common site of spinal tumour
a. Extramedullary intradural
b. Extra dural
c. Intra medullary
d. Extra meduralary extradural
35. All are essential components of TOF except:
a. Valvular pulmonic stenosis
b. Right ventricular hypertrophy
c. Infundibular stenosis
d. Aorta overriding
36. When stem cell transforms to form other tissues, the
process is called as:
a. Dedifferentiation b. Redifferentiation
c. Transdifferentiation d. Subdifferentiation
37. The communicating vein responsible for spread of
infection from the Dangerous area of the face.
a. Superior ophthalmic Vein
b. Inferior Ophthalmic Vein
c. Maxillary Vein
d. Lingual Vein
38. Artery to vas deferens is a branch of
a. Inferior epigastric b. Superior vesical
c. Cremasteric d. Middle rectal
39. What is the origin of the definitive myocardium of the
adult heart?
a. Endoderm
b. Somatopleuric mesoderm
c. Hypoblast
d. Splanchnopleuric mesoderm
40. an infarct causing bilateral infarction of the occipital
lobes is likely to be secondary to occlusion in the
territory of the :
a. The Posterior Cerebral Artery
b. The Basilar Artery
c. The superior cerebellar artery
d. The anterior inferior cerebellar artery
41. Most fascia of the body that attach to bones attach by
which of the following mechanisms?
a. Blending with the covering periosteum
b. Inserting deeply into the cancellous bone
c. Inserting deeply into the cartilage
d. Inserting deeply into the diaphysis
42. Which of these statements about Scalenus anterior is
true
a. Is an accessory muscle of respiration
b. Lies anterior to the suprascapular artery
c. Is pierced by the phrenic nerve
d. Inserts into the scalene tubercle on the second rib
43. Which of the following respiratory system components
is derived from neural crest?
a. Endothelial cells
b. Epithelium of primary bronchi
c. Laryngeal cartilage
d. Tracheal glands
44. An infarct involving the seventh nerve and nucleus is
likely to be secondary to occlusion in the territory of the:
a. The Posterior Cerebral Artery
b. The Basilar Artery
c. The superior cerebellar artery
d. The anterior inferior cerebellar artery
45. A patient has a tumour based in an enlarged jugular
foramen , what is the most likely presentation?
a. Eight cranial nerve palsy
b. Ninth cranial nerve palsy
c. Tenth cranial nerve palsy
d. Eleventh cranial nerve palsy
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46. True about diaphragm is
a. Develops from the septum transversum and cervical
myotomes
b. Receives a nerve supply from phrenic nerve only
c. The inferior vena cava passes through the diaphragm at
the level of the T12 vertebra
d. The aorta passes through the diaphragm at the level of
the T8 vertebra
47. Which cranial nerve exits the skull base at the pars
nervosa of the jugular foramen ?
a. Eight cranial nerve palsy
b. Ninth cranial nerve palsy
c. Tenth cranial nerve palsy
d. Eleventh cranial nerve palsy
48. The following structures pass under the inguinal
ligament
a. The tendon of psoas major
b. The femoral branch of the genitofemoral nerve
c. The long saphenous vein
d. The superficial epigastric vein
49. The axilla contains all except
a. The cords of the brachial plexus
b. The superior thoracic artery
c. The latissimus dorsi muscle in its medial wall
d. The thoracodorsal nerve in its posterior wall
50. What suspensory ligaments connect the outer edge of
the lens of the eye with the ciliary processes?
a. Zonnules of Zinn b. Zonnules of Schlemm
c. Cruciate ligaments d. Ligaments of Treitz
51. Closure of the neural tube occurs on around which day
of the embryonic life period?
a. 26 b. 38 c. 56 d. 74
52. Which of the following is true of the optic disc?
a. No arteries pass through it
b. No veins pass through it
c. It appears dark red on fundoscopy
d. It is normally less than 1cm in diameter
53. An infarct causes a pure motor herniparesis . This
infarct is likely to be secondary to occlusion in the
territory of the :
a. The Posterior Cerebral Artery
b. Deep penetrating lacunar artery
c. The superior cerebellar artery
d. The anterior inferior cerebellar artery
54. The most common sex chromosomal aneuploidy in males
is
a. XX karyotype b. XXY karyotype
c. XO karyotype d. XXX karyotype
55. The buccinator muscle:
a. Is attached to both jaws opposite the molar teeth
b. Is supplied by the V nerve
c. Is continuous with the superior constrictor of the
pharynx
d. Is a muscle of mastication
56. Nerves that pass in the lateral wall of the cavernous
sinus include:
a. The ophthalmic division of the trigeminal nerve
b. The sixth cranial nerve
c. The anterior ethmoidal nerve
d. The optic nerve
57. The nerve supplying submandibular gland is
a. V b. VII c. IX d. XII
58. The muscle least related to pterygomandibular raphe is
a. Superior pharyngeal constrictor b. Medial pterygoid
c. Lateral pterygoid d. Buccinator
59. The radial nerve
a. Is the principal branch of the posterior cord of the
brachial plexus
b. Is derived from the posterior primary rami of the C5 to
T1 nerve roots
c. Is the main nerve supply to the flexor compartments of
the arm and forearm
d. Supplies sensation to the extensor aspect of the radial
three and a half digits
60. The heart of an embryo first begins beating at which of
the following ages?
a. 2 weeks b. 3 weeks
c. 4 weeks d. 6 weeks
61. Which of these statements about oesophagus is true
a. Is 40 cm in length
b. Is lined by stratified squamous epithelium in the upper
two-thirds
c. Is lined by transitional epithelium in the lower one-
third
d. Drains all of its blood into the azygos and hemiazygos
veins
62. A 36-year-old Asian male complains of difficulty
swallowing. Esophagoscopy reveals a polypoid mass
that is subsequently biopsied. In addition to tumor cells,
the esophageal biopsy show normal smooth muscle and
striated muscle in the same section. Which portion of
the esophagus was the source of this biopsy?
a. Lower esophageal sphincter
b. Lower third of the esophagus
c. Middle third of the esophagus
d. Upper esophageal sphincter
63. Contraction of which of the following muscles
contributes most to the backward movement of the
lower jaw during the process of mastication?
a. Digastric b. Lateral pterygoid
c. Medial pterygoid d. Temporalis
64. Which of the following hormones is secreted by anterior
pituitary cells that stain with acidic dyes?
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a. ACTH b. FSH
c. LH d. Prolactin
65. A 7-year-old patient presents with a mass in the anterior
midline of the neck, slightly above the larynx. The mass
is mobile and elevates upon protrusion of the tongue.
This mass is most likely a cyst that developed from
which of the following embryonic structures?
a. First pharyngeal cleft
b. First pharyngeal pouch
c. Second pharyngeal cleft
d. Thyroglossal duct
66. Zygomycosis, a destructive fungal infection of the
sinuses, is likely to reach the brain by which of the
following routes?
a. Cavernous sinus
b. External carotid artery
c. Internal carotid artery
d. Superior sagittal sinus
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67. Which of these statements about the thymus gland is
false
a. Develops from the fourth pharyngeal pouch
b. Decreases in size with age
c. Is made up of cells of endodermal origin
d. Descends anterior to the brachiocephalic vein
68. The morphofunction unit of the breast is composed of:
a. The aveoli and the large duct system
b. The lobule and the stroma
c. The lactiferous sinus and the terminal ductules
d. The TDLU (terminal duct lobular unit) and the large
duct system
69. What is the length of the Human spermatozooa
(Sperm)?
a. 50 micrometers b. 100 micrometers
c. 200 micrometers d. 500 micrometers
70. Which of the following stimulus does not induce visceral
pain ?
a. Distension b. Pressure
c. Cauterisation d. Cutting
71. Which of these statements about the pancreas gland is
false
a. Lies anterior to the left kidney
b. Derives part of its blood supply from the splenic artery
only
c. Has parts in both the supracolic and infracolic
compartments
d. Is pierced by the middle colic artery
72. A 25-year-old female presents to her obstetrician after
taking a home pregnancy test with a positive result. She
states that twins run in her family and would like an
ultrasound to determine if she has a twin pregnancy.
Radiographic studies confirm that the embryo has split
at the blastocyst stage. Splitting of the embryo at the
blastocyst stage results in which of the following?
a. Conjoined twins
b. Dizygotic twins
c. Fraternal twins
d. Monozygotic twins
73. A newborn male child is noted to have hypospadias. A
complete evaluation determines that the child has no
other genitourinary anomalies. Nonetheless, hyposp-
adias repair will be performed to prevent which of the
following possible sequelae?
a. Bladder exstrophy
b. Hydrocele
c. Phimosis
d. Urinary tract infection
74. A 12-month-old child is diagnosed with an atrial septal
defect. What is the most common cause of such a
congenital heart malformation?
a. Failure of formation of the septum primum
b. Failure of formation of the septum secundum
c. Incomplete adhesion between the septum primum and
septum secundum
d. Malformation of the membranous interventricular
septum
75. Which of the pharyngeal pouches develops into the pal-
atine tonsil?
a. First b. Second c. Third d. Fourth
76. During anatomy lab, a medical student notes a fibrous
band that runs on the visceral surface of the liver. It is
attached on one end to the inferior vena cava and on the
other end to the left branch of the portal vein. In the
embryo, this structure corresponds to the
a. Ductus venosus b. Ligamentum teres
c. Ligamentum venosum d. Umbilical arteries
77. At which of the following ages does fetal movement first
occur?
a. 1 month b. 2 months c. 4 months d. 6 months
78. A patient, who appears to be female, is found to be 46,
XY. The patient's vagina is very shallow, ending in a
blind pouch, and there are palpable masses in the labia.
The diagnosis of testicular feminization syndrome is
made. Which of the following was most likely present
during the early fetal life of this individual ?
a. A streak ovary
b. A uterus
c. Depressed levels of testosterone
d. MIF (Mullerian inhibitory factor)
79. The smooth part of the right atrium derives from which
of the following embryonic structures?
a. Bulbus cordis b. Primitive atrium
c. Primitive ventricle d. Sinus venosus
80. Which of the following characteristics is similar for
spermatogenesis and oogenesis?
a. Age at which meiosis begins
b. Amount of cytoplasm retained
c. DNA replication during meiosis
d. Length of prophase I
81. In a genotypic male, the testes fail to develop, and do
not secrete testosterone or Müllerian regression factor.
Which of the following best describes the in utero
reproductive system development of this individual?
a. Both male- and female-type internal reproductive tracts
and male-type external genitalia
b. Female-type internal reproductive tract and female-
type external genitalia
c. Female-type internal reproductive tract and male-type
external genitalia
d. Male-type internal reproductive tract and female-type
external genitalia
82. Which of these statements about the common bile duct
is false
a. Lies in the free edge of the lesser omentum
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b. Lies anterior to the portal vein
c. Lies to the right of the hepatic artery
d. Lies anterior to the first part of the duodenum
83. From which of the following fetal vessels do the umbil-
ical arteries arise?
a. Aorta
b. Carotid arteries
c. Ductus arteriosus
d. Iliac arteries
84. Thoracic duct is also called
a. Hensen’s duct
b. Bernard’s duct
c. Pecquet duct
d. Hoffman’s duct
85. The greater omentum is derived from which of the
following embryonic structures?
a. Dorsal mesoduodenum
b. Dorsal mesogastrium
c. Pericardioperitoneal canal
d. Pleuropericardial membranes
86. The lateral pterygoid muscle attaches to which of
the following?
a. Lateral surface of the lateral pterygoid plate.
b. Medial surface of the lateral pterygoid plate.
c. Lateral surface of the medial pterygoid plate.
d. Medial surface of the medial pterygoid plate.
87. Which of the following muscles is responsible for
the formation of the posterior tonsillar pillar?
a. Stylopharyngeus.
b. Tensor veli palatine.
c. Palatoglossus.
d. Palatopharyngeus.
88. The superior and inferior ophthalmic veins drain
into the
a. Internal jugular vein
b. Pterygoid plexus
c. Frontal vein
d. Facial vein
89. The masseter originates from the
a. Condyle of the mandible
b. Infratemporal crest of the sphenoid bone
c. Inferior border of the zygomatic arch
d. Pyramidal process of the palatine bone
90. Which of the following muscles adducts the vocal
cords?
a. Lateral cricoarytenoid.
b. Posterior cricoarytenoid.
c. Cricothyroid.
d. Vocalis.
91. Which of the following strata of oral epithelium is
engaged in mitosis?
a. Basale. b. Granulosum.
c. Corneum. d. Spinosum.
92. The auriculotemporal nerve encircles which of the
following vessels?
a. Maxillary artery.
b. Superficial temporal artery.
c. Deep auricular artery.
d. Middle meningeal artery.
93. The muscle that is found in the walls of the heart is
characterized by '
a. A peripherally placed nucleus
b. Multiple nuclei
c. Intercalated discs
d. Fibers with spindle-shaped cells
94. All of the following are found in the posterior tria-
ngle of the neck except one. Which one is the
exception?
a. External jugular vein. b. Subclavian vein.
c. Hypoglossal nerve. d. Phrenic nerve.
95. Deoxygenated blood from the transverse sinus dra-
ins into the
_
a. Inferior sagittal sinus
b. Confluence of sinuses
c. Sigmoid sinus
d. Straight sinus
96. The vestigial cleft of Rathke's pouch in the hypop-
hysis is located between the
.
a. Anterior and posterior lobes
b. Anterior lobe and hypothalamus
c. Posterior lobe and hypothalamus
d. Median eminence and the optic chiasm
97. Involution of the thymus would occur following
which year in a healthy individual?
a. 0 years (at birth). b. 12th year.
c. 20th year. d. 60thyear.
98. Blood from the internal carotid artery reaches the
posterior cerebral artery by the
a. Anterior cerebral artery
b. Anterior communicating artery
c. Posterior communicating artery
d. Posterior superior cerebellar artery
99.
The infraorbital nerve is a branch of the
a. Optic nerve
b. Oculomotor nerve
c. Ophthalmic nerve
d. Maxillary nerve
100. The most distal portion of the maxillary alveolar bone
is the
a. Tuberosity b. Retromolar area
c. Palatine raphe d. Palatine fovea
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1. Ans A. Nerve fibers Pulp and Dentin entering the teeth have been identified histologically as myelinated A-fibers and
unmyelinated C-fibers. These fibers are grouped in bundles and enter through the apical foramina of the teeth, passing through the
radicular to the coronal pulp where they fan out and diverge into smaller bundles. Nerve divergence continues; individuals-fibers
within small bundles lose their myelin sheath and divide repeatedly before finally ramifying into a plexus of single axons known as
the subodontoblastic plexus or plexus of Raschkow. The exact function of this plexus is unknown, as is the changing configuration of
the plexus with dentin formation." From this plexus nerve fibers are distributed toward the pulp-dentin border with terminals showing
a characteristic bead-like structure.
2. Ans A. Explanation: Mnemonic is Atal Bihari Vajpayee (ABV) -Arrangement of pulmonary structures at the hilum of the lungs -
ABV: From (A)bove to below: (A)rtery-(B)ronchus-(v)ein. -Pulmonary artery is uppermost whereas, pulmonary vein is inferior
most. -This applies well to left lung...for right lung one additional bronchus goes above the artery and is called as ep-arterial
bronchus. -Hence, in the right lung the uppermost structure in the hilum will be a bronchus.
NOTE: There are 2 veins which are named anterior & inferior according to their location at the hilum. (Similar arrangement on both
sides) -Bronchus & bronchial arteries are always posterior most structures at the hila of both lungs.
3. Ans D. Explanation: Ulnar nerve supplies the Adductor pollicis muscle and hence it will be paralysed in its lesion. Hence,
adduction of thumb is not a clinical finding in ulnar nerve palsy.
4. Ans B. Explanation: Left renal vein crosses in front of the aorta from right to left towards the left kidney. -Additional information:
The vein lies below the superior mesenteric artery (L-1 vertebral level) and above the renal artery (lies between L-1 & L-2 vertebra)
-Because the inferior vena cava is on the right side of the body, the left renal vein is generally the longer of the two.
- Now, because the inferior vena cava is not laterally symmetrical, the left renal vein often receives the following veins:
left inferior phrenic vein left suprarenal vein
left gonadal vein (left testicular vein in males, left ovarian vein in females) left 2nd lumbar vein
-This is in contrast to the right side of the body, where these veins drain directly into the IVC.
5. Ans A. Classification of Cementum Based on the Nature and Origin of Collagen Fibers.
Organic matrix derived form 2 sources: Periodontal ligament (Sharpey’s fibers)
Cementoblasts
Extrinsic fibers derived from PDL. These are in the same direction of the PDL principal fibers i.e. perpendicular or oblique to the
root surface. Intrinsic fibers derived from cementoblasts. Run parallel to the root surface and at right angles to the extrinsic fibers
The area where both extrinsic and intrinsic fibers is called mixed fiber cementum.
6. Ans B. Explanation: Coarctation (stenosis/narrowing) of aorta is due to defect in the tunica media, which forms a shelf like
projection into the lumen, most commonly in the region of the ductus arteriosus.
-A collateral circulation develops distal to the obstruction between subclavian artery (internal thoracic artery) & descending aorta
(posterior intercostal arteries).
-This anastomosis produces characteristic notching of the ribs on X-RAY
Superior epigastric is a branch of internal thoracic artery and gives the anterior intercostal arteries in the lower intercostal spaces.
-Coarctation of the aorta is of three types:
1. Pre-ductal coarctation: The narrowing is proximal to the ductus arteriosus. If severe, blood flow to the aorta distal (to lower body)
to the narrowing is dependent on a patent ductus arteriosus, and hence its closure can be life-threatening.
2. Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus
arteriosus closes.
3. Post-ductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus blood
flow to the lower body can be impaired. Newborns with this type of coarctation may be critically sick from the birth.
7. Ans A. Explanation:
1. Agenesis of the Corpus Callosum (ACC) is a rare birth defect (congenital disorder) in which there is a complete or partial absence
of the corpus callosum. Agenesis of the corpus callosum occurs when the corpus callosum, the band of tissue connecting the two
hemispheres of the brain, does not develop typically in utero. In addition to agenesis of the corpus callosum, other callosal disorders
include hypogenesis (partial formation), dysgenesis (malformation) of the corpus callosum, and hypoplasia (underdevelopment) of the
corpus callosum.
Signs and symptoms: Signs and symptoms of Agenesis of the Corpus Callosum and other callosal disorders vary greatly among
individuals. However, some characteristics common in individuals with callosal disorders include vision impairments, low muscle
tone (hypotonia), poor motor coordination, delays in motor milestones such as sitting and walking, low perception of pain, delayed
toilet training, chewing and swallowing difficulties, early speech and language delays, and social difficulties. Recent research
suggests that specific social difficulties may be a result of impaired face processing. Unusual social behavior in childhood is often
mistaken for or misdiagnosed as Asperger's syndrome or other autism spectrum disorders. Other characteristics sometimes associated
with callosal disorders include seizures, spasticity, early feeding difficulties and/or gastric reflux, hearing impairments, abnormal
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head and facial features, and mental retardation.
8. Ans C. Explanation: -The weakest link in the marginal chain of vessels (of Drummond) is near the left colic (splenic) flexure,
between the middle colic artery (mid-gut) & the left colic artery (hind-gut).
-An inner arterial circle (of Riolan) between the ascending branch of left colic artery and the trunk of middle colic artery may
supplement the blood supply to this region of colon. "Watershed area" is the medical term referring to regions of the body that receive
dual blood supply from the most distal branches of two large arteries, such as the splenic flexure of the large intestine.
During times of blockage of one of the arteries that supply of the watershed area, such as in atherosclerosis, these regions are spared
from ischemia by virtue of their dual supply. However, during times of systemic hypoperfusion, such as in DIC or Heart failure, these
regions are particularly vulnerable to ischemia by virtue of the fact that they are supplied by the most distal branches of their arteries,
and thus the least likely to receive sufficient blood.
9. Ans D. Explanation:
-Gall bladder is lined by columnar cells with irregular microvilli-brush border.
-Small intestine is lined by microvilli arranged in regular fashion -striated border.
-Brush border is also present in the proximal convoluted tubule (PCT) of kidney.
-Stereo-cilia are present in the hair cells of internal ear and epididymis.
10. Ans B. Sharpey's Fibers = direct extensions of dense irregular CT from periosteum into compact bone. Functions to anchor tendon
(with fibers penetrating periosteum to bone) to bone. Formation by appositional bone growth around original attachment site.
The periodontal ligament is much more cellular and more highly vascularized than ordinary ligaments, reflecting its high rate of
protein turnover. It consists of collagen and some elastic fibers. The collagenous fibers penetrate into the cementum and into the
surrounding bone. When properly stained, the fibers within cementum and bone are visible and referred to as Sharpey's fibers.
11. Ans b. Explanation:
-During a thoracic procedure in mid-axillary line, the external & internal intercostal muscles are always punctured.
-Inner most layer : Of the three group of muscles in this layer, the innermost intercostals are at the side of the rib cage,
-Subcostalis are at the back and Transversus thoracis at the front of the thoracic cage.
-Hence, Transversus thoracis will not be punctured in a mid axillary line approach.
NOTE: Transversus thoracis muscle was formerly called as sterno-costalis, more exactly. In fact, now TRANSVERSUS THORACIS
includes all the three inner layer muscles, namely - Subcostalis, innermost intercostal (intercostalis intimi) and the sterno-costalis.
12. Ans A. Explanation:
-The dangerous area of the eye is the region in the neighborhood of the ciliary
Body, and wounds or injuries in this situation are peculiarly dangerous.
13. Ans A. Explanation: -Urothelium (or transitional) epithelium starts in the minor calyx region and lines major calyx, pelvis,
ureter, urinary bladder and the proximal 2 cm of prostatic urethra.
-Collecting ducts are lined by columnar epithelium
14. Ans C. Transseptal fibers
Types of gingival fibers
There are three groups within which gingival fibers are arranged: gingivodental group - there are three types of fibers within this
group: fibers that extend towards the crest of the gingiva fibers that extend laterally to the outer surface of the gingiva and fibers that
extend outward, past the height of the alveolar crest, and then downward along the cortex of the alveolar bone. circular group - these
fibers are unique in that they exist entirely within the gingiva and do not contact the tooth transseptal group - these fibers have
traditionally been described as spanning the interproximal tissue between adjacent teeth, into which they are embedded. However,
two other types of fibers have been described in this group:
semicicular fibers - fibers that run through the facial and lingual gingiva around each tooth, attaching to the interproximal surfaces of
the same tooth.
transgingival fibers - fibers that run between two non-adjacent teeth and are embedded in the cementum of their proximal surfaces,
passing around the tooth in the middle of the two teeth attached with these fibers.
15. Ans C: DENTIN : It consists of about 80% hydroxyapatite (by dry weight) and 20% of organic matrix (collagen, proteoglycans,
glycosaminoglycans) and is pervaded by the dentinal tubules. On the outside, the dentin is covered either by enamel (anatomical
crown) or by cementum. On its inner surface facing the pulp chamber and the root canal, the dentin is lined by the odontoblasts,
which are columnar cells arranged in a single layer (fig. 19). Each odontoblast sends a cytoplasmic process into one dentinal tubule,
reaching as far as 1/2 the thickness of the dentin. Odontoblasts are not separated from the pulp by a basement membrane. A plexus of
capillaries extends within the odontoblast layer close to the predentin (a thin uncalcified layer of dentin matrix facing the pulp
chamber). The odontoblasts are of mesenchymal origin, synthesizing and secreting the components of the dentinal matrix. They
secrete first a layer of predentin, which stains pale in H&E and PAS preparations. The odontoblasts furthermore secrete a
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phosphoprotein that is deposited specifically at the predentin-dentin junction. Apparently this phosphoprotein initiates the
calcification of dentin. Dentin stains strongly with H&E and PAS
16. Ans C. Embrasure: The space between two teeth which opens out from their contact point.
17. Ans D. Explanation: -Rhodopsin is present in the retinal rods -The basement membrane consists of an electron-dense membrane
called the lamina densa, about 30–70 nanometers in thickness, and an underlying network of reticular collagen (type IV) fibrils (its
precursor is fibroblasts) which average 30 nanometers in diameter and 0.1–2 micrometers in thickness. This type IV collagen is of the
reticular type, in contrast to the fibrillar collagen found in the interstitial matrix. -The Lamina Densa (which is made up of type IV
collagen fibers; perlecan (a heparan sulfate proteoglycan) coats these fibers and they are high in heparan sulfate) and the Lamina
Lucida (made up of laminin, integrins, entactins, and dystroglycans) together make up the basal lamina. -Lamina Reticularis attached
to basal lamina with anchoring fibrils (type VII collagen fibers) and microfibrils (fibrilin) is collectively known as the basement
membrane.
18. Ans D. Explanation: -Perforators connect the superficial veins with the deep veins. -There are about 5 perforators along the great
saphenous vein - 1.in the mid-thigh; 2. Below knee; 3, 4 & 5. near the lower leg and ankle. -Great saphenous vein itself drains into the
femoral vein below the inguinal ligament.
19. Ans A. Explanation: -Tongue muscles develop from occipital myotomes and are innervated by the 12 nerve.
20. Ans C. Explanation:
-The pain of pericarditis originates in the parietal layer only and is transmitted by the phrenic nerve.
-The fibrous and parietal layer of serous pericardium is supplied by the phrenic nerve.
-Visceral layer is insensitive.
21. Ans B. Explanation: -Meiosis - I changes primary spermatocyte into secondary spermatocyte.
-Then, Meiosis - II changes secondary spermatocyte into the spermatid.
22. Ans C. Explanation: -Mesonephric duct (Wolffian duct) gives the ureteric bud which further develops into ureter.
23. Ans B. Explanation: Psoas sign: flexion of or pain on hyperextension of the hip due to contact between an inflammatory process
and the psoas muscle; a sign often seen in appendicitis. Called also Cope’s sign.
-The inflamed appendix lies on the psoas muscle and the patient will lie with the right hip flexed for pain relief.
-Extension of hip will cause pain
Rovsing's sign: Rovsing sign, pressure over the point on the left side corresponding to the McBurney point will elicit the typical pain
at the McBurney point on the right side in appendicitis.
-Deep palpation of the left iliac fossa causes pain in the right iliac fossa.
Obturator sign: If an inflamed appendix is in contact with the obturator internus, spasm of the muscle can be demonstrated by flexing
and internally rotating the hip. This manouvre will cause pain in the hypogastrium.
24. Ans B. Explanation:
Hyaline & elastic cartilage contain type-II collagen, whereas fibro-cartilage is more like bone & contain type-I cartilage.
25. Ans A. Metaphysis as we all know is the most metabolically active part of the bone with rapid cell turn over and most vascular
part also. Since it is the most vascular part we have the Osteomyelitis that spreads through hematogenous route originate here in
children and is one of the areas that get fractured in pathological fracturesof the bone. The zone of maturation is more vulnerable
1. It is the weakest part of bone and so this is a wrong statement. 2. It is the most vascular part of bone.
3. Growth activity is maximized here. 4. It is the region favouring hematogenous spread of infection.
26. Ans A. Muscles of Mastication
Muscle
Origin
Insertion
Action
Temporalis
Temporal bone
Parietal bone
Coronoid process
Elevates jaw
Retracts jaw
Masseter
Zygomatic arch
Mandibular angle
Elevates jaw
Lateral Pterygoid (Superior Head) Sphenoid bone
Temporomandibular Disk Draws articular disk forward
Lateral Pterygoid (Inferior Head) Lateral Side of Lateral Pterygoid Plate Mandibular neck
(bilaterally) Protracts jaw
(unilaterally) Abducts jaw
(grinding)
Medial Pterygoid
Medial Side of Lateral Pterygoid Plate Mandibular angle
Elevates jaw
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27. Ans B.Explanation: In emergency tracheostomy following structures can be damaged:
-Isthmus -Inferior thyroid veins
-thyroid artery -left brachio-cephalic vein
-pleura (especially infants) -Thymus
28. Ans A. Greater Petrosal Nerve is joined by the deep petrosal nerve from the internal carotid sympathetic plexus to become the
Vidian nerve or nerve of the pterygoid canal which traverses the pterygoid canal to end in the pterygopalatine ganglion.
29. Ans A.Explanation: Kanavel's sign, a point of maximum tenderness in the palm 2.5 cm proximal to the base of the little finger in
infection of tendon sheath.- goal is to distinguish infectious tenosynovitis from superficial or localized abscess
Kanavel's Four Cardinal Signs
- Discussion:
- for diagnosing infectious tenosynovitis;
- intense pain accompanies any attempt to extend partly flexed finger;
- this is absent in local involvement;
- pain will be noted along the course of tendon with extension;
- this is the earliest and most important sign;
- in case of a local furuncle, in contrast, the finger can be held straight without much pain;
- flexion posture: finger is held in flexion for comfort;
- uniform swelling involving entire finger in contrast to localized swelling in local inflammation;
- percussion tenderness along the course of the tendon sheath;
- tenderness is marked along the course of inflamed sheath in contrast to its absence in a localized inflammation;
30. Ans c. Explanation: -Gastrin is a hormone that stimulates secretion of gastric acid by the parietal cells of the stomach. It is
released by G cells in the stomach and duodenum.
-Somatostain- Delta cells (delta-cells or D cells) are somatostatin producing cells.
They can be found in the stomach, intestine and the Islets of Langerhans in the pancreas.
-Insulin is synthesized in the pancreas within the beta cells (beta-cells) of the islets of Langerhans.
-One to three million islets of Langerhans (pancreatic islets) form the endocrine part of the pancreas, which is primarily an exocrine
gland. The endocrine portion only accounts for 2% of the total mass of the pancreas. Within the islets of Langerhans, beta cells
constitute 60–80% of all the cells.
31. Ans A. Transversalis Fascia: The spermatic cord in the male, or the round ligament of the uterus in the female, pass through the
transversalis fascia at the deep inguinal ring (see below). This opening is not visible externally since the transversalis fascia is
prolonged on these structures as the internal spermatic fascia
Layers of Anterior Abdominal Wall
Layers of Scrotum
Mnemonic Skin S Some Superficial Fascia Dartos Muscle D Decent External Oblique Abdominis External Spermatic Fascia E
Englishmen Internal Oblique Abdominis
Cremateric Muscle and Fascia C Call Transversalis Fascia Internal Spermatic Fascia
It Process Vaginalis Tunica Vaginalis Testis T Testis
32. Ans A.Explanation: -Sertoli cell (a kind of sustentacular cell) is a 'nurse' cell of the testes which is part of a seminiferous tubule.
It is activated by follicle-stimulating hormone, and has FSH-receptor on its membranes.
-FSH binds to Sertloi cells stimulate testicular fluid production and synthesis of intracellular androgen receptor proteins. Sertoli cells
secrete anti- mullerian hormone and activins also.
-LH binds to receptors on interstitial cells of Leydig and stimulate testosterone production, which in turn binds to Sertoli cells to
promote spermatogenesis.
-Inhibin is a hormone that inhibits FSH production.It is secreted from the Sertoli cells,located in the seminiferous tubule inside the
testes.
33. Ans A. The external laryngeal nerve, smaller than the internal, descends posterior to the sternothyroid with the superior thyroid
artery but on a deeper plane; it lies at first on the inferior pharyngeal constrictor and then, piercing it, curves round the inferior thyroid
tubercle to reach and supply the cricothyroid. It also supplies the pharyngeal plexus and inferior constrictor; behind the common
carotid artery it connects with the superior cardiac nerve and superior cervical sympathetic ganglion.
34. Ans D.Explanation: Spinal cord tumours- Epidural metaststic tumours are the most common.
-most copmmon - neoplastic cord compression is nearly always due to extra-medullary, extradural metastses usually from breast,
lung, prostate, lymphoma or renal cancers.
-Compression usually occurs by posterior expansion of vertebral metastases or extension of paraspinal metastses through the
intervertebral foramina.
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-These result in demyelination, arterialcompromise, venous occlusion and vasogenic oedema of the spinal cord, all contributing to
myelopathy. 70 % occur in the thoracic spine, 20 % lumbar spine and 10 % cervical spine.
-Ependymomas are the most common primary spinal tumour, accounting for about 66 % oa all intramedullary tumours. They are
usually located around the lower cord, conus medullaris anf filum terminale.
-Spinal astrocytoma are the second most common primary spinal tumour, accounting for about 30 % of all intramedullary tumours
35. Ans A. Explanation: In TOF Infundibular stenosis occurs due to anterior migration of AP septum.
-There is no valvular stenosis in TOF.
36. Ans c. Explanation: Transdifferentiation: a non-stem cell transforms into a different type of cell, or when an already
differentiated stem cell creates cells outside its already established differentiation. --Transdifferentiation: 1. The change of a cell or
tissue from one differentiated state to another. 2. The differentiation of a tissue-specific stem cell into another type of cell as, for
example, a bone marrow stem cell differentiating into a neuron.
-Transdifferentiation is a type of metaplasia, which includes all cell fate switches, including the interconversion of stem cells.
-Evidence for transdifferentiation in adult humans is given by Barrett's metaplasia in which epithelieal cells of the esophagus switch
to intestinal mucin-secreting goblet cells.
Differentiation: 1 The process by which cells become progressively more specialized;
-a normal process through which cells mature. This process of specialization for the cell comes at the expense of its breadth of
potential. Stem cells can, for example, differentiate into secretory cells in the intestine. 2 In cancer, differentiation refers to how
mature (developed) the cancer cells are in a tumor.
-Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated or poorly
differentiated tumor cells, which lack the structure and function of normal cells and grow uncontrollably.
-Dedifferentiation: Dedifferentiation is a cellular process where a partially or terminally differentiated cell reverts to an earlier
developmental stage.
- a loss of differentiation of cells and of their orientation to one another and to their axial framework and blood vessels, a
characteristic of tumor tissue; also called anaplasia.
-Redifferentiation:the return of a dedifferentiated tissue or part to its original or another more or less similar condition.
-SUB-DIFFERENTIATION: Further differentiation into sub-types eee.g., T lymphocytes sub-differentiate into Helper, killer and
suppressor subsets.
37. Ans A. Near its beginning the facial vein connects with the superior ophthalmic directly and via the supraorbital; it is thus
connected to the cavernous sinus.
38. Ans. B.Explanation: Vas deferens is supplied by a separate artery, which is a branch of superior vesical artery(2).
-This artery of vas deferens anastomoses with the testicular artery. Testis is mainly supplied by the testicular artery, an anterior branch
of aorta. -Testis receives additional blood from the artery of ductus deferens and also from cremasteric(3) branch of inferior epigastric
artery(1).
39. Ans D. Myocardium - The myocardium, or cardiac muscle arises from splanchnopleuric mesoderm that invests the primary heart
tube. The myocardium secretes the cardiac jelly and gives rise to the conduction system.
Epicardium (visceral pericardium) - This outer tunic of thin serous membrane covers the myocardium. It is derived from
splanchnopleuric mesoderm and also forms the coronary vessels.
Endocardium - This lining of the heart tube is derived from the lateral endocardial tubes. It consists of endothelium and a thin
subendothelial connective tissue.
40. Ans A. Explanation. Atherothrombosis of the PCA is relatively uncommon, but when it occurs is generally in the proximal
segment of the vessel. Sometimes thrombus may spread by contiguous ascent from the basilar apex. PCA infarction rarely involves
the entire arterial territory; and the variability of the resulting clinical deficits of primary sensory, visual and behavioral function
depend upon the degree of damage to the thalamus, occipital and inferomedial temporal lobes respectively. Blockage of vessels
derived from the proximal PCA can cause infarction in sensory and motor nuclei of the thalamus and nearby subthalamic structures.
41. Ans A. Fascial straps (retinacula) and fascial coverings of muscles or muscle groups characteristically attach to nearby bones by
blending with the covering periosteum. No deep attachments are usually made by fascia. Cancellous bone (choice B) is spongy bone,
which is usually found in marrow, and is not the site for fascial attachment. Fascia do not usually attach to cartilage (choice C). Fascia
attaches to bony shafts, or diaphyses (choice D), superficially via the periosteum.
42. Ans B. Scalenus anterior arises from the transverse processes of the third to six cervical vertebrae. It inserts into the scalene
tubercle of the first rib. The subclavian vein passes anteriorly. The subclavian artery and brachial plexus pass posteriorly. The phrenic
nerve lies on the anterior surface.
43. Ans C. Laryngeal cartilages (e.g., the thyroid, cricoid, arytenoid cartilages) are derived from neural crest.
The endothelial cells in the simple squamous epithelium that lines the pulmonary capillaries are derived from visceral mesoderm.
The epithelial lining of primary bronchi is derived from endoderm.
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Tracheal glands and epithelium both derive from endoderm.
Type I pneumocytes are derived from endoderm.
44. Ans D.Explanation: The AICA territory includes the middle cerebellar peduncle, fifth nerve sensory nucleus and tract, seventh
nerve and nucleus, eighth nerve, vestibular nuclei and the descending sympathetic tracts. AICA-related lateral Pontine infarction
produces a syndrome similar to Wallenberg's; but instead of hoarseness, palatal weakness and loss of taste, there is ipsilateral facial
paralysis and deafness.
45. Ans A. Explanation. The glossopharyngeal (ie, CN IX), vagus (ie, CN X), and accessory (ie, CN XI) nerves emerge cranial to
caudal, in that order, from the ventral medulla, lateral to the medullary olive. From there, they course toward the jugular foramen and
exit the skull base at the jugular foramen. The glossopharyngeal nerve is located in the pars nervosa of the jugular foramen, and the
vagus and accessory nerves are located within the more posterior pars vascularis. The hypoglossal nerve (CN XII) is formed by the
fusion of multiple rootlets that emerge from the ventrolateral sulcus between the medullary olive and pyramid. The nerve exits the
cranial vault via the hypoglossal canal, then lies medial to CN IX, CN X, and CN XI. Schwannomas in the jugular foramen that arise
from the glossopharyngeal, vagus, or accessory nerves, can present with variable cerebellar and acoustic symptoms, depending on the
extent of the intracranial growth of the mass. They also can cause glossopharyngeal dysfunction (eg, hoarseness, difficulty
swallowing) and/or spinal accessory symptoms (eg, trapezius atrophy). Schwannomas of the jugular foramen are rare. Patients often
present with symptoms consistent with eighth cranial nerve injury or cerebellar or brain stem compression. Symptoms relating to
injury of the ninth or 10th to 12th cranial nerves are less common. Although the clinical presentation of a schwannoma of the jugular
foramen may suggest the presence of a vestibular schwannoma, appropriate imaging techniques and interpretation should permit
correct differentiation of tumor origin and type and suggest the appropriate surgical approach. Schwannoma of the jugular foramen
appears as a sharply demarcated, contrast-enhancing tumor, which is typically centered or based in an enlarged jugular foramen with
sharply rounded bone borders having a sclerotic rim. The clinical presentation of schwannomas of the jugular foramen varies
significantly according to the tumor's growth pattern. Deafness, vertigo, and ataxia were present if the mass is intracranial. Most
patients present with symptoms of decreased hearing; Hoarseness and weakness of the trapezius and sternocleidomastoid muscles
occur in some patients in whom the tumor is within the bone or extracranial. In patients with a large proportion of the tumor below
the skull base, the symptoms tended to reflect glossopharyngeal injury.
46. Ans A: The diaphragm develops in the neck and hence receives its nerve supply from the cervical spinal cord (C4-C5). It is made
up of structures arising from the septum transversum, pleuroperitoneal membranes, the dorsal mesentery and body wall. The septum
transversum forms the central tendon. The motor nerve supply arises from the phrenic nerve. The sensory nerve supply is from the
lower six intercostal nerves. The IVC, oesophagus and aorta pass through the diaphragm at the levels of T8, T10 and T12
respectively.
47. Ans B. Explanation: The glossopharyngeal (ie, CN IX), vagus (ie, CN X), and accessory (ie, CN XI) nerves emerge cranial to
caudal, in that order, from the ventral medulla, lateral to the medullary olive. From there, they course toward the jugular foramen and
exit the skull base at the jugular foramen. The glossopharyngeal nerve is located in the pars nervosa of the jugular foramen, and the
vagus and accessory nerves are located within the more posterior pars vascularis. The hypoglossal nerve (CN XII) is formed by the
fusion of multiple rootlets that emerge from the ventrolateral sulcus between the medullary olive and pyramid. The nerve exits the
cranial vault via the hypoglossal canal, then lies medial to CN IX, CN X, and CN XI. Schwannomas in the jugular foramen that arise
from the glossopharyngeal, vagus, or accessory nerves, can present with variable cerebellar and acoustic symptoms, depending on the
extent of the intracranial growth of the mass. They also can cause glossopharyngeal dysfunction (eg, hoarseness, difficulty
swallowing) and/or spinal accessory symptoms (eg, trapezius atrophy). Schwannomas of the jugular foramen are rare. Patients often
present with symptoms consistent with eighth cranial nerve injury or cerebellar or brain stem compression. Symptoms relating to
injury of the ninth or 10th to 12th cranial nerves are less common. Although the clinical presentation of a schwannoma of the jugular
foramen may suggest the presence of a vestibular schwannoma, appropriate imaging techniques and interpretation should permit
correct differentiation of tumor origin and type and suggest the appropriate surgical approach. Schwannoma of the jugular foramen
appears as a sharply demarcated, contrast-enhancing tumor, which is typically centered or based in an enlarged jugular foramen with
sharply rounded bone borders having a sclerotic rim. The clinical presentation of schwannomas of the jugular foramen varies
significantly according to the tumor's growth pattern. Deafness, vertigo, and ataxia were present if the mass is intracranial. Most
patients present with symptoms of decreased hearing; Hoarseness and weakness of the trapezius and sternocleidomastoid muscles
occur in some patients in whom the tumor is within the bone or extracranial. In patients with a large proportion of the tumor below
the skull base, the symptoms tended to reflect glossopharyngeal injury.
48. Ans a,b: The tendon of psoas major and the femoral branch of the genitofemoral nerve both pass under the inguinal ligament. The
long saphenous vein terminates in the femoral vein about 3 cm below the inguinal ligament.The superficial epigastric vein passes in
front of the inguinal ligament
49. Ans. B. The axilla contains the cords of the brachial plexus. The latissimus dorsi muscle forms the posterior wall of the axilla. It is
supplied by the thoracodorsal nerve. The long thoracic nerve supplies serratus anterior and lies on the medial wall.
50. Ans. A. Explanation: Also known as the suspensory ligament, the Zonnules of Zinn comprise a network of collagen fibres
which connect the outer edge of the lens with the ciliary processes. In this hammock of fine fibres lies the lens. To the right is the
margin of the vitreous humour, to the left is the posterior chamber, which lies between the zonnules and the iris. Below in the ciliary
processes lie cells which are excreting aqueous humour, which flows to the pupil.
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51. Ans A. Explanation: As the neural tube forms, the closing process is critical, occurring from the cranial to the caudal end as the
anterior neuropore closes around day 24, the posterior around day 26. This is a critical event, as defects in closure may result in spina
bifida or other neural tube defects. The risk of a neural tube defect can be decreased by folic acid supplements.
52. Ans. D. Explanation: This is the point at which axons leave the eyeball and join the optic nerve. Also, arteries enter and veins
leave the retina at the optic disk. There are no photoreceptors here, hence it is known as the 'blind spot'. It is a pinky-yellow oval,
approximately 2mm in diameter, and situated in the nasal retina
53. Ans. B. Explanation: Lacunes are caused by occlusion of a single penetrating artery. The deep penetrating arteries are small
nonbranching end arteries (usually smaller than 500 mm in diameter), which arise directly from much larger arteries (eg, the middle
cerebral artery, anterior choroidal artery, anterior cerebral artery, posterior cerebral artery, posterior communicating artery, cerebellar
arteries, basilar artery). Their small size and proximal position predispose them to the development of microatheroma and
lipohyalinosis. Lacunar strokes, which comprise the most common paradigm of small vessel infarction, account for 10% of all
strokes. Several distinct lacunar syndromes are recognized: the most common is pure motor herniparesis. The clinical characteristics
of this syndrome include severe herniparesis or herniplegia involving the limbs, face and trunk often with associated dysarthria.
Notably absent are sensory disturbance, visual or language deficits. The site of such infarctions are within the corona radiata, internal
capsule, cerebral peduncle, pons and rarely the medullary pyramid. The pure sensory stroke produces hemisensory deficits involving
the face, limbs and trunk contralateral to the small infarction in the ventral posterior thalamic nucleus which causes the syndrome.
Lacunar infarction in the genu or anterior limb of the internal capsule or pontine base produce clumsy hand-dysarthria syndrome
which manifests clinically as clumsiness of the contralateral hand and tongue with contralateral facial paresis. Homolateral ataxia and
crural paresis result from pontine lacunes involving post-decussating cerebellar tracts and pre-decussating corticospinal tracts. The
resultant signs are of mild contralateral hemiparesis involving leg more than arm or face with more marked ataxia of the weak limbs.
Bilateral lacuries within the internal capsule in perithalamic locations may result in a mutism syndrome. The accrual of multiple
lacunae within the internal capsules of both hemispheres may result in a pseudobulbar syndrome in which there is dysarthria,
hyperactive gag reflex with dysphagia, spasticity especially of the lower limbs extensor plantar reflexes, gait apraxia with small
hesitant steps and emotional incontinence. This lacunar state is a major part of subcortical atherosclerotic encephalopathy. There is
evolving evidence that microvascular occlusive disease can be due not only to thrombotic or obliterative disease but also to embolic
processes. Intra. and extracranial arterial sources are implicated as is cardioembolism of microparticulate matter.
54. Ans B. Explanation: Klinefelter's syndrome occurs in approximately 1/500 to 1/1,000 newborn males. There is a 47XXY
chromosome complement, representing the most common sex chromosomal aneuploidy in males
55. Ans A. BUCCINATOR, is the most deeply located facial muscle forming the muscular foundation of the cheek. During
mastication, the buccinator in conjunction with the tongue, places the food between the upper and lower teeth for grinding. In
addition, since its most anterior muscular fibres extend into the upper and lower lips, the action of the muscle (in conjunction with
that of the orbicularis oris), not only closes the mouth, but pressed the lips back upon the teeth, pulls the angle of the mouth laterally
and flattens the cheek. It arises from the outer surfaces of the alveolar processes of the maxilla and mandible, corresponding to the
three molar teeth; and behind, from the anterior border of the pterygomandibular raphé which separates it from the superior
constrictor of the pharynx.
The PAROTID DUCT (excretory) emerges from its (parotid glands) superficial portion, courses medially contacting the anterior
border of the masseter muscle and the buccal fat pad, then, passes deeply through the buccinator muscle to open into the oral cavity
opposite the second maxillary molar tooth. Motor innervation is from the facial nerve (cranial nerve VII), and sensory innervation is
from the buccal branch of the trigeminal nerve (cranial nerve V).
56. Ans A. Cavernous sinus lies between the cranial and meningeal layers of the dura mater beside the body of the sphenoid bone;
cranial nn. III, IV and V1 are in its lateral wall; the internal carotid a. and cranial n. VI are in its lumen
57. Ans. B. Parasympathetic innervation to the submandibular glands is provided by the superior salivatory nucleus via the chorda
tympani, a branch of the facial nerve that synapses in the submandibular ganglion after which it follows the Lingual nerve leaving this
nerve
as
it
approaches
the
gland.
Increased
parasympathetic
activity
promotes
the
secretion
of
saliva.
The sympathetic nervous system regulates submandibular secretions through vasoconstriction of the arteries that supply it. Increased
sympathetic activity reduces glandular bloodflow, thereby decreasing salivary secretions and producing an enzyme rich serous saliva.
58. Ans. C. The pterygomandibular raphé (pterygomandibular ligament) is a tendinous band of the buccopharyngeal fascia, attached
by one extremity to the hamulus of the medial pterygoid plate, and by the other to the posterior end of the mylohyoid line of the
mandible.
Its medial surface is covered by the mucous membrane of the mouth.
Its lateral surface is separated from the ramus of the mandible by a quantity of adipose tissue.
Its posterior border gives attachment to the superior pharyngeal constrictor muscle.
Its anterior border attaches to the posterior edge of the buccinator.
An obese patient is brought into the emergency room in shock and in need of intravenous fluids. No superficial veins can be seen or
palpated. The emergency room physician decides to make an incision to locate the great saphenous vein for the insertion of a cannula
("saphenous cutdown"). In which of the following locations should the incision be made?
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59. Ans A. The radial nerve is the main branch of the posterior cord of the brachial plexus. Other branches of the posterior cord
include the axillary, thoracodorsal and upper and lower subscapular nerves. All roots of the brachial plexus arise from the anterior
primary rami. The radial nerve supplies the forearm and wrist extensors; A radial nerve palsy results in a classical 'wrist drop'. The
anterior and posterior interosseus nerves are branches of the median and radial nerves respectively.
60. Ans C. While the third-week embryo is a primitive trilaminar plate, in the fourth week, the heart begins to form and begins
beating almost immediately. Hematopoiesis occurs in the yolk sac, and a primitive circulatory system connects the capillary plexuses
of the yolk sac and chorion to the embryo. Partitioning of the atrium also begins in the fourth week. During the fifth week, cardiac
septa form and the atrioventricular (AV) cushions fuse. By the sixth week, the heart is close to fully formed. This early sequence for
the heart explains why it is so difficult to try to prevent congenital malformations of the cardiovascular system from occurring, since
the mother of a 6-week-old fetus is only about 8 weeks from her last menstrual period, and may have assumed that she just "missed a
period" (a very common phenomenon) for reasons other than pregnancy.
61. Ans B. The oesophagus is 25 cm in length. The oesophagogastric junction lies 40 cm from the incisors. The oesophagus is lined
by both striated (upper two-thirds) and smooth (lower third) muscle. The lower third is line by columnar epithelium. The venous
drainage is into the inferior thyroid, azygos and left gastric veins. The communication between the azygos and left gastric veins is an
important portosystemic anastomosis that can be the site of oesophageal varices
62. Ans C. The muscularis of the upper third of the esophagus is composed entirely of striated muscle. The middle third (choice C)
contains both striated and smooth muscle. The lower third (choice B) and lower esophageal sphincter (choice A) contain only smooth
muscle. There is no such thing as the upper esophageal sphincter (choice D).
63. Ans D. Mastication is a complex process involving alternating elevation, depression, forward movement, and backward
movement of the lower jaw. The backward movement step is accomplished by the posterior fibers of the temporalis muscle.
The digastric helps to depress the lower jaw during chewing.
The lateral pterygoid helps to move the lower jaw forward during chewing.
The medial pterygoid helps to elevate the lower jaw during chewing.
The mylohyoid helps to depress the lower jaw during chewing.
64. Ans D. The cells of the anterior pituitary can be classified as chromophils & chromophobes (do not stain with dyes). The
chromophils can be further divided into acidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils
include the somatotropes, which secrete growth hormone, and the mammotropes, which secrete prolactin. The basophils include the
corticotropes, which secrete ACTH (choice A), the gonadotropes, which secrete FSH and LH (choices B and C), and the thyrotropes,
which secrete TSH
65. Ans D. The thyroglossal duct develops as an evagination of the floor of the pharynx in the region where the tongue develops. The
adult foramen cecum of the tongue marks the site of this evagination. The distal end of this duct normally forms the thyroid gland; the
proximal part of the duct normally degenerates. Failure of a part of the duct to degenerate may lead to a thyroglossal duct cyst or
median cervical cyst, as seen in this patient.
The first pharyngeal cleft (choice A) forms the external ear canal. This cleft normally remains patent.
The first pharyngeal pouch (choice B) forms the middle ear cavity and the auditory tube. This pouch normally remains patent.
The second pharyngeal cleft (choice C) normally does not remain patent. It is typically covered over by the overgrowth of the second
pharyngeal arch. If part of this pouch does remain patent, it may form a lateral cervical cyst, which is seen on the lateral side of the
neck along the posterior border of the sternocleidomastoid muscle.
The second pharyngeal pouch forms the tonsillar fossa of the pharynx. The pharyngeal mucosa in this area arises from the endoderm
of the pouch. Ingrowth of mesoderm cells results in the formation of the palatine tonsil.
66. Ans A. The cavernous sinuses are located on either side of the body of the sphenoid bone, and become a potential route of
infection because they receive blood both from the face (via the ophthalmic veins and sphenoparietal sinus) and some of the cerebral
veins. The spread of infection, especially by Mucor sp., into the cavernous sinus, can produce either CNS infection or cavernous sinus
thrombosis, both of which are potentially fatal.
The route from the face to the brain is not arterial (choices B and C).
The superior sagittal sinus (choice D) is located in the falx cerebri, and drains venous blood from the brain to other dural sinuses,
from which it eventually drains into the jugular vein.
Zygomycosis does not reach the brain by way of the superior sagittal sinus.
The superior vena cava drains blood from the upper part of the body into the heart.
67. Ans A. The thymus lies within the anterior mediastinum. It develops with the inferior parathyroid gland from the third pharyngeal
pouch. The cells of the thymus are of endodermal origin. It is at its largest in childhood and decreases in size with age
68. Ans D. The morphofunctional unit of the breast is composed of two units
- Terminal duct lobular unit (TDLU)
- consists lobule and smaller terminal ductules
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- together empty into the segmental duct, then the lactiferous sinus, then the collecting duct
- Large collecting ducts
- Most of the breast stroma consists a loose connective tissue,
adipose tissue
, elastic fibers that support the larger ducts (interlobular
stroma)
- However each lobule is surrounded by the intralobular stroma (hormonal responsive stroma)
- Blood supply of the breast is predominantly from the internal mammary artery and lateral thoracic artery
- Lymphatic drainage is a valveless unidirectional flow from superficial to deep
- Majority of lymphatic drainage is to axillary nodes, 97%
- 3% going to internal mammary chain
69. Ans A. The measurements of different parts of spermatozoon :-
Head - 4.0 µm Neck - 0.3 µm Middle piece - 7 µm
Principal piece - 40 µm End piece - 5-7µm Approximately 58.3µm
As it is released from the wall of the seminiferous tubule into the lumen, the spermatozoon is non-motile but structurally mature. Its
expanded head contains little cytoplasm and is connected by a short constricted neck to the tail. The tail is a complex flagellum and is
divided into middle, principal and end pieces. The head contains the elongated flattened nucleus with condensed, deeply staining
chromatin and the acrosomal cap anteriorly, which contains
acid phosphatase
, hyaluronidase, neuraminidase and proteases necessary
for fertilisation. In the centre of the neck, is a well formed centriole, corresponding to the proximal centriole of the spermatid from
which it differentiated The axonemal complex is derived from the distal centriole. A small amount of cytoplasm exists in the neck
covered by plasma membrane continuous with that of the head & tail. The middle piece - a long cylinder - consists of an axial bundle
of microtubules, the axoneme, outside which is a cylinder of nine dense outer fibres, surrounded by a helical mitochondrial sheath.
The annulus is an electron - dense body at the caudal end of the middle piece. The principal piece - motile part of cell - The axoneme
and the surrounding dense fibres are continuous from the neck region through the whole length of the tail except for its terminal 5-
7µm, in which the axoneme alone persists. The end piece has a typical structure of a flagellum, with a simple nine plus two
arrangement of microtubules.
,
70. Ans: (c) Cauterisation;(d) Cutting
Viscera are insensitive to: - cutting - crushing - burning
However visceral pain is caused by Excessive distension Spasmodic contraction of smooth muscles Ischemia
The pain felt in the region of the viscus is called true visceral pain
Referred pain : Pain arising in viscera may also be felt in the skin or other somatic tissues, supplied by somatic nerves arising from
the same spinal segment. If the inflammation spreads from a diseased viscus to the parietal peritoneum it causes local somatic pain
overlying body wall. In acute appendicitis pain is at first felt in the peri umbilical region (T10) and then is localised to Mcburney’a
point.
71. ans D. The tail of the pancreas crosses the left kidney as it passes to the hilum of the spleen. The blood supply is from the splenic,
superior and inferior pancreaticoduodenal arteries. The gland is pierced by the superior mesenteric artery. The middle colic arises
from the lower border.
72. Ans D. Explanation: Monozygotic twins, or identical twins, develop from a single fertilized egg that subsequently splits during
either the blastomere or blastocyst stage. It is more common in the blastocyst stage at the end of the first week. This results in two
inner cell masses in the same blastocyst cavity. They usually develop a common placenta and chorionic cavities but separate amniotic
cavities. Splitting in the second week usually results in shared amniotic cavities as well. Conjoined twins (choice A), or Siamese
twins, result from incomplete splitting of the embryo. Dizygotic twins (choice B) and fraternal twins (choice C) are the same, and are
the most common type of twins. They share the same genetic relatedness as do siblings of separate pregnancies. This type of twinning
occurs because of simultaneous double ovulation followed by fertilization by two sperm. They each develop their own placenta and
membranes.
73. Ans D. Explanation: Hypospadias, which is congenital displacement of the urethral opening onto the ventral surface (underside)
of the penis, is due to malformation of the urethral groove and canal. Hypospadias frequently accompanies other genitourinary
anomalies, especially cryptorchidism. Isolated hypospadias is repaired because the abnormal opening is often constricted, leading to
urinary retention and ascending urinary tract infections. Another important consequence of hypospadias is sterility, which occurs if
the opening is too close to the base of the penis to permit normal ejaculation. Although hypospadias can occur in isolation, it is
strongly associated with other urogenital anomalies. Bladder exstrophy (choice A) is a completely unrelated congenital malformation
in which the abdominal wall and anterior bladder wall form incompletely, and the bladder mucosa is exposed to the environment.
Hydrocele (choice B) is a serous accumulation in the tunica vaginalis, often producing a readily apparent scrotal mass. Hydrocele
usually arises without any obvious cause. Phimosis (choice C) is the condition in which the foreskin cannot be retracted over the head
of the penis. It is usually either a congenital malformation or a consequence of scarring.
74. Ans C. Explanation: The most common form of atrial septal defect is located near the foramen ovale (not to be confused with a
patent foramen ovale, which is of little or no hemodynamic significance). They result from incomplete adhesion between the septum
primum and the septum secundum during development. Atrial septal defects less commonly result from failures of formation of the
septum primum (choice A) and septum secundum (choice B). Malformations of the interventricular septum (choices D) cause
ventricular septal defects rather than atrial septal defects.
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75. Ans B. Explanation: The epithelial lining of the second pharyngeal pouch buds into the mesenchyme to form the palatine tonsil.
Part of the pouch remains in the adult as the tonsillar fossa. The first pharyngeal pouch (choice A) develops into the middle ear cavity
and eustachian tube. The third pharyngeal pouch (choice C) develops into the thymus and the inferior parathyroid glands. The fourth
pharyngeal pouch (choice D) gives rise to the superior parathyroid glands. Recall that abnormal development of the 3
rd
and 4th
pouches leads to DiGeorge syndrome and results in hypocalcemia as well as abnormal cellular immunity and consequent
susceptibility to viral and fungal illnesses. The fifth pharyngeal pouch gives rise to the C cells of the thyroid gland. These cells secrete
calcitonin–a hormone that lowers serum calcium.
76. ans A. Explanation: This question could have tricked you if you didn't catch the key words, "in the embryo." If you read the
question too quickly and thought you were going to be asked to identify the structure described, you probably chose choice C
(ligamentum venosum), since that is indeed the structure in question. However, in the embryo, this fibrous band is actually the ductus
venosus. The ductus venosus is an embryonic vessel that allows blood to bypass the fetal liver; this prevents the depletion of oxygen
and nutrient-rich blood in the hepatic sinusoids. The embryonic umbilical vein (choice E) actually becomes the fibrous ligamentum
teres (choice B). The ligamentum teres is located in the free margin of the falciform ligament. The embryonic umbilical arteries
(choice D) become the medial umbilical ligaments.
77. Ans B. Explanation: Neuromuscular development is sufficient to allow fetal movement in the eighth week of life. Other features
of week 8 include the first appearance of a thin skin, a head as large as the rest of the body, forward-looking eyes, appearance of
digits on the hands and feet, appearance of testes and ovaries (but not distinguishable external genitalia), and a crown-rump length of
approximately 30 mm. By the end of the eighth week, nearly all adult structures have at least begun to develop, and the fetus "looks
like a baby".
78. Ans. D. Explanation: Testicular feminization is a disorder of the androgen receptor. Phenotypically, the patient appears female,
but has a blindly ending vagina and lacks a uterus or other female internal reproductive organs. The patient has an XY genotype.
Since the gene for testes determining factor (TDF) is on the Y chromosome, TDF will cause the indifferent gonad to develop into a
testis containing Sertoli cells. Sertoli cells at this stage will secrete MIF, a substance that suppresses the paramesonephric ducts,
preventing the formation of female internal reproductive organs. This patient would not have a streak ovary , a finding in Turner's
syndrome that is associated with a 45,XO genotype. In fact, the patient would have testes, since the genetic complement contained a
Y chromosome. The testes in individuals with testicular feminization syndrome are often undescended and are usually removed
surgically. This patient would not possess a uterus. Both of these structures are derived from the paramesonephric duct, which is
suppressed by MIF. Depressed levels of testosterone would not occur in this patient. In fact, individuals with testicular feminization
syndrome have normal or even slightly elevated levels of testosterone. The development of female external genitalia is the result of
defective androgen receptors, not depressed levels of testosterone.
79. Ans D. Explanation: The smooth part of the right atrium (the sinus venarum) is derived from the sinus venosus. The coronary
sinus and the oblique vein of the left atrium also derive from the sinus venosus. The bulbus cordis (choice A) gives rise to the smooth
part of the right ventricle (conus arteriosus) and the smooth part of the left ventricle (aortic vestibule). The primitive atrium (choice B)
gives rise to the trabeculated part of the right and left atria.The primitive ventricle (choice C) gives rise to the trabeculated part of the
right and left ventricles.
80. Ans C. Explanation: The actual process of manipulation of DNA and chromosomes during meiosis is very similar in
spermatogenesis and oogenesis. However, the processes also differ in many other respects: In oogenesis, the process of meiosis
begins before birth, and arrests between birth and puberty in prophase I. In contrast, spermatogenesis does not begin until puberty (see
choice A). The egg retains a large volume of cytoplasm (choice B), while nearly all the cytoplasm is stripped during formation of a
sperm. As noted above, in oogenesis, meiosis is arrested in prophase I, which is consequently very prolonged in the female. In
spermatogenesis, meiosis is completed in a much shorter time (choice D).
NOTE: Both the egg and the sperm have mitochondria, but those of the sperm are left outside when the sperm nucleus enters the egg,
and consequently do not contribute to the mitochondrial genome of the fetus. Instead, the mitochondria are transmitted from the egg
to the fetus. Traits coded for by mitochondrial DNA are therefore inherited in a matrilineal fashion.
81. Ans B. Explanation: The description is that of gonadal dysgenesis. In the absence of testosterone, the Wolffian ducts will regress
and fail to differentiate into normal male internal reproductive tracts. In the absence of Müllerian regression factor, the Müllerian
ducts will automatically differentiate into oviducts and a uterus. Differentiation of the male external genitals is dependent on adequate
dihydrotestosterone (via an action of 5 α- reductase on testosterone). In the absence of testosterone, female-type external genitalia will
develop. Selective dysgenesis of the Sertoli cells could produce the situation described in choice A. Normal Leydig cells would
secrete testosterone and produce normal male-type internal and external tracts. However, the absence of Müllerian regression factor,
which is secreted by the Sertoli cells, would allow formation of female-type internal structures as well. Female-type internal
reproductive tract and male-type external genitalia (choice C) would not be likely to occur under any circumstances. The situation
described in choice D could occur with 5 α-reductase deficiency. Normal male-type internal tracts can form because there is no
requirement for dihydrotestosterone. Müllerian regression factor will prevent differentiation of female-type internal tracts. Since
differentiation of the normal male external genitals requires dihydrotestosterone, 5 α- reductase deficiency will lead to feminization.
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82. Ans D. The common bile duct lies in the free edge of the lesser omentum, anterior to the portal vein and to the right of the hepatic
artery. It passes posterior to the first part of the duodenum before opening into the second part.
83. Ans D. Explanation: The paired umbilical arteries arise from the iliac arteries. They supply unoxygenated fetal blood to the
placenta. The single umbilical vein takes the newly oxygenated fetal blood from the placenta to the liver and then to the inferior vena
cava via the ductus venosus.
84. Ans C. Pecquet duct
Hensen’s duct: ductus reuniens, a small canal leading from the saccule to the cochlear duct; called also canalis reuniens, Hensen's
canal or duct, and Reichert's canal.
Bernard’s duct: ductus pancreaticus accessorius, accessory pancreatic duct: a small inconstant duct draining a part of the head of the
pancreas into the minor duodenal papilla; called also minor pancreatic duct, and duct of Santorini or Bernard.
Pecquet duct: The major efferent lymph duct into which lymph from most of the peripheral lymph nodes drains.
Recirculating lymphocytes that have left the circulation in the lymph node return to the blood through the thoracic duct.
Hoffman’s duct: pancreatic duct. The excretory duct of the pancreas that extends through the gland from tail to head where it empties
into the duodenum at the greater duodenal papilla.
Synonym: ductus pancreaticus, Hoffmann's duct, Wirsung's canal, Wirsung's duct.
85. Ans B. Explanation: Both the omental bursa and the greater omentum are derived from the dorsal mesogastrium, which is the
mesentery of the stomach region.
The dorsal mesoduodenum (choice A) is the mesentery of the developing duodenum, which later disappears so that the duodenum and
pancreas come to lie retroperitoneally.
The pericardioperitoneal canal (choice C) embryologically connects the thoracic and peritoneal canals.
The pleuropericardial membranes (choice D) become the pericardium and contribute to the diaphragm.
86. Ans A. The inferior head of the lateral pterygoid muscle attaches to the lateral surface of the lateral pterygoid plate of
sphenoid bone. Its superior head attaches to the infratemporal crest of the greater wing of sphenoid bone. The deep fibers of
the medial pterygoid muscle attaches to the medial surface of the lateral pterygoid plate.
87. Ans D. The palatopharyngeus forms the posterior tonsillar pillar. It also functions to close off the nasopharynx and larynx
during swallowing. The anterior tonsillar pillar is formed by the palatoglossus.
88. Ans D. The superior and inferior -ophthalmic veins drain into the facial vein and cavernous-:5inus.
89. Ans C. The masseter originates from the inferior border of the zygomatic arch; specifically, its superficial head and deep
head originate from the anterior two thirds or posterior one third of the inferior border, respectively. Its superficial head inserts
into the lateral surface of the angle of the mandible; its deep head inserts into the ramus and body of the mandible.
90. Ans A. Lateral cricoarytenoid. The oblique and transverse arytenoids and thyroartenoid also adduct the vocal folds. The
posterior cricoarytenoids abducts the vocal cords. The cricothyroid muscle raises the cricoid cartilage and tenses the vocal
cords.
91. Ans A. The site of cell division (mitosis) occurs in the stratum basale (basal layer, stratum germinativum) of oral
epithelium.
92. Ans D. After branching from the mandibular nerve (CN V;>, the auriculotemporal nerve travels posteriorly and encircles the
middle meningeal artery, remaining posterior and medial to the condyle. It then continues up towards the TMJ, external ear,
and temporal region, passing through the parotid gland and traveling with the superficial temporal artery and vein.
93. Ans C. Intercalated discs are only found in cardiac muscle. Multiple, peripherally positioned nuclei are found in the fibers
of skeletal muscle. Smooth muscle cells are spindle-shaped.
94. Ans C. The hypoglossal (CN XII) nerve is not found in the posterior triangle;. it is, however, present in the submandibular
triangle. Contents of the posterior triangle include the external jugular and subclavian vein and their tributaries, the subclavian
artery and its branches, branches of the cervical plexus, CN XI, nerves to the upper limb and muscles of the triangle floor, the
phrenic nerve, and the brachial plexus.
95. Ans C. Deoxygenated blood from the transverse sinus drains to the sigmoid sinus, which empties into the internal jugular
veins. The transverse sinuses receive blood from the confluence of sinuses, which is located in the posterior cranium.
96. Ans A. The vestigial cleft of Rathke's pouch is located between the anterior and posterior lobesspecifically, between the
pars intermedia and anterior lobe. It consists of cyst-like spaces (Rathke's cysts) and represents the vestigial lumen of Rathke's
pouch.
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97. Ans B. The thymus is active at birth and increases in size until puberty (around age 12), after which it gradually atrophies
and is replaced by fatty tissue.
98. Ans C. The internal carotid artery is joined to the posterior cerebral artery via the posterior communicating artery, which is
part of the circle of Willis.
99. Ans D. It is a branch of the maxillary (CN V
2
) nerve. The maxillary nerve branches from the trigeminal ganglion and exits
the skull through the foramen rotundum. When it reaches the pterygopalatine ganglion, it terminates as the infraorbital and
zygomatic nerves.
100. Ans A