PGIMER Entrance Anatomy Syllabus

Name the four sites of portosystemic anastomosis and their clinical manifestations.

1) Lower esophagus (left gastric ↔ azygos) → esophageal varices. 2) Anal canal (superior rectal ↔ middle/inferior rectal) → rectal varices. 3) Periumbilical (paraumbilical ↔ epigastric) → caput medusae. 4) Retroperitoneal (colic ↔ renal/lumbar veins, veins of Retzius).

Which veins form the portal vein and at what vertebral level?

Formed by the union of the superior mesenteric vein and the splenic vein behind the neck of the pancreas at the level of L2. The inferior mesenteric vein usually drains into the splenic vein.

What are the components of the pelvic diaphragm and the gap it leaves anteriorly?

Levator ani (puborectalis, pubococcygeus, iliococcygeus) and coccygeus. Anteriorly it leaves the urogenital hiatus through which the urethra (and vagina in females) passes.

Describe the relationship of the ureter to the uterine artery in females.

The uterine artery crosses anterior (and superior) to the ureter near the lateral fornix of the vagina - 'water (ureter) under the bridge (uterine artery)'. Clinically important during hysterectomy.

What are the boundaries and subdivisions of the anterior triangle of the neck?

Boundaries: anterior border of sternocleidomastoid, midline of neck, inferior border of mandible. Subtriangles: submental, submandibular (digastric), carotid, and muscular triangles.

Name the layers of the deep cervical fascia.

Investing (encloses trapezius and SCM), pretracheal (encloses thyroid, trachea, esophagus), prevertebral (covers vertebral column muscles), and the carotid sheath (formed by contributions of all three).

What are the contents of the carotid sheath?

Common/internal carotid artery (medially), internal jugular vein (laterally), vagus nerve (posteriorly between them), and deep cervical lymph nodes. The ansa cervicalis is embedded in its anterior wall.

List the 12 cranial nerves and their functional category (sensory/motor/both).

I Olfactory(S), II Optic(S), III Oculomotor(M), IV Trochlear(M), V Trigeminal(B), VI Abducens(M), VII Facial(B), VIII Vestibulocochlear(S), IX Glossopharyngeal(B), X Vagus(B), XI Accessory(M), XII Hypoglossal(M). 'Some Say Marry Money But My Brother Says Big Brains Matter Most.'

Which cranial nerve nuclei lie in the midbrain, pons, and medulla?

Midbrain: III (oculomotor), IV (trochlear). Pons: V (motor/sensory), VI, VII, VIII. Medulla: IX, X, XI (cranial part), XII. The nucleus ambiguus (IX, X, XI) and solitary nucleus span the medulla.

Which cranial nerve has the longest intracranial course and is the only one to emerge dorsally from the brainstem?

The trochlear nerve (CN IV). It also supplies the superior oblique muscle and is the only cranial nerve that decussates before emerging.

Describe the formation of the Circle of Willis.

Anterior: two anterior cerebral arteries joined by the anterior communicating artery. Lateral/posterior: internal carotids give posterior communicating arteries joining the posterior cerebral arteries (from basilar). It links the internal carotid and vertebrobasilar systems.

Which artery supplies the lateral surface of the cerebral hemisphere and which is the most common site of aneurysm?

The middle cerebral artery (MCA) supplies most of the lateral surface. The most common site of berry (saccular) aneurysm is the anterior communicating artery.

What deficit results from occlusion of the anterior cerebral artery?

Contralateral motor and sensory loss affecting the lower limb more than the upper limb/face (medial homunculus), and possible urinary incontinence and abulia.

What are the limbs and bends of the internal capsule, and what major tract passes through the posterior limb?

Anterior limb, genu, posterior limb, retrolenticular and sublenticular parts. The corticospinal tract and sensory thalamocortical fibres run in the posterior limb; corticobulbar fibres in the genu.

Name the components of the basal ganglia and the structures forming the corpus striatum and lentiform nucleus.

Caudate nucleus, putamen, globus pallidus, plus functionally subthalamic nucleus and substantia nigra. Corpus striatum = caudate + lentiform. Lentiform nucleus = putamen + globus pallidus. Neostriatum = caudate + putamen.

Trace the flow of CSF through the ventricular system.

Lateral ventricles → interventricular foramina of Monro → third ventricle → cerebral aqueduct of Sylvius → fourth ventricle → foramina of Luschka (lateral, x2) and Magendie (median) → subarachnoid space → absorbed by arachnoid granulations into the superior sagittal sinus.

Describe the course and decussation of the lateral corticospinal tract.

Originates in the motor cortex, descends through internal capsule and brainstem, ~85-90% of fibres decussate at the pyramidal (motor) decussation in the lower medulla, then descend in the lateral funiculus to synapse on anterior horn cells. Controls contralateral limb movement.

Compare the dorsal column-medial lemniscus pathway and the spinothalamic tract (modality, decussation level).

DCML: fine touch, vibration, proprioception; first-order neuron ascends ipsilaterally, decussates in the medulla (internal arcuate fibres). Spinothalamic: pain and temperature; decussates within 1-2 segments at the spinal cord level (anterior white commissure).

What are the classifications of epithelium based on the number of layers and cell shape, with one example each?

Simple squamous (alveoli), simple cuboidal (kidney tubules), simple columnar (gut), pseudostratified (trachea), stratified squamous (skin/esophagus), stratified cuboidal (sweat ducts), transitional/urothelium (bladder).

List the types of connective tissue proper and the main fibre and cell types.

Loose (areolar) and dense (regular/irregular) connective tissue. Fibres: collagen, elastic, reticular. Cells: fibroblasts (resident), macrophages, mast cells, plasma cells, adipocytes. Ground substance contains GAGs and proteoglycans.

Compare the three muscle types (skeletal, cardiac, smooth) by striations, nuclei, and control.

Skeletal: striated, multinucleate (peripheral nuclei), voluntary. Cardiac: striated, central single nucleus, intercalated discs, involuntary. Smooth: non-striated, single central nucleus, spindle-shaped, involuntary.

Describe the histological structure of the classic hepatic lobule and the zones of the liver acinus.

Hexagonal lobule with a central vein and portal triads (hepatic artery, portal vein, bile duct) at corners; hepatocyte plates radiate outward separated by sinusoids. Acinus zones: Zone 1 (periportal, best oxygenated), Zone 2, Zone 3 (centrilobular, most susceptible to ischemia).

Describe the components of a renal corpuscle and the cells of the juxtaglomerular apparatus.

Renal corpuscle = glomerulus + Bowman's capsule, with visceral (podocytes) and parietal layers. JGA: juxtaglomerular (granular) cells of the afferent arteriole (secrete renin), macula densa of the distal tubule, and extraglomerular mesangial (lacis) cells.

Differentiate the histology of the adrenal cortex zones and their secretions.

Zona glomerulosa: mineralocorticoids (aldosterone). Zona fasciculata: glucocorticoids (cortisol). Zona reticularis: androgens. Medulla: catecholamines (chromaffin cells). Mnemonic 'GFR - Salt, Sugar, Sex.'

Describe the histology of the thyroid gland and the function of its two cell types.

Follicles lined by follicular (principal) cells surrounding colloid (thyroglobulin) - produce T3/T4. Parafollicular (C) cells lie between follicles or in the wall and secrete calcitonin.

Compare spermatogenesis and oogenesis in terms of timing and number of gametes produced.

Spermatogenesis: continuous from puberty, one primary spermatocyte → 4 spermatozoa, ~64 days. Oogenesis: begins in fetal life (arrests in prophase I until puberty, metaphase II until fertilization), one primary oocyte → 1 ovum + polar bodies.

Where does fertilization normally occur and what is the result of the cortical reaction?

Fertilization occurs in the ampulla of the uterine (fallopian) tube. The cortical reaction (release of cortical granules) causes the zona reaction, hardening the zona pellucida to prevent polyspermy.

Describe the stages from fertilization to implantation with their timing.

Day 1: zygote. Day 2-3: cleavage (2-16 cell morula). Day 4-5: blastocyst (inner cell mass + trophoblast + blastocele). Day 5-6: hatching from zona. Day 6-7: implantation begins in the posterior superior uterine wall; completed by ~day 9-10.

List the major derivatives of the three germ layers (ectoderm, mesoderm, endoderm).

Ectoderm: epidermis, nervous system, neural crest derivatives, enamel. Mesoderm: muscle, bone, connective tissue, blood/cardiovascular, kidneys, gonads, dermis. Endoderm: epithelial lining of GI/respiratory tracts, liver, pancreas, thyroid, bladder.

Match each pharyngeal arch to its cranial nerve and a key skeletal derivative.

1st: CN V (trigeminal) - Meckel's cartilage (malleus, incus, mandible). 2nd: CN VII (facial) - Reichert's cartilage (stapes, styloid, hyoid lesser horn). 3rd: CN IX (glossopharyngeal) - hyoid greater horn. 4th/6th: CN X (vagus, superior and recurrent laryngeal) - laryngeal cartilages.

Define teratogen and give the critical period of greatest susceptibility to major congenital anomalies.

A teratogen is an agent (drug, infection, radiation, chemical) that causes congenital malformations. The greatest susceptibility is during the embryonic period (weeks 3-8) of organogenesis; weeks 1-2 follow an 'all-or-none' effect, and the fetal period (9+ weeks) mainly affects function/growth.