First M.B.B.S. Anatomy Paper II - August 2025 | Complete Answers

Section-A (Q1) — 20 × 1 = 20 Marks

Posterior dislocation of the hip is the classic dashboard injury. The limb is shortened, internally rotated, and adducted because the femoral head dislocates posteriorly and superiorly. Anterior dislocation causes external rotation and abduction.

The sciatic nerve passes through the gluteal region, and injections in the lower medial quadrant (the "dangerous zone") risk piercing the nerve. The correct injection site is the upper outer quadrant. Sciatic nerve injury causes foot drop (common peroneal division affected). The inferior gluteal nerve supplies gluteus maximus; the pudendal nerve is medial.

This is tarsal tunnel syndrome. The tibial nerve (and its branches - medial and lateral plantar nerves) passes through the tarsal tunnel posterior to the medial malleolus. Tinel's sign here is pathognomonic.

A hernia emerging lateral to the inferior epigastric vessels passes through the deep inguinal ring and inguinal canal - this is an indirect inguinal hernia. Direct inguinal hernias emerge medial to these vessels through Hesselbach's triangle.

The linea alba is a fibrous band formed by the interlacing aponeuroses of the three flat abdominal muscles, running in the midline of the anterior abdominal wall from xiphoid process to pubic symphysis. It lies anterior to the peritoneum and between the two rectus abdominis muscles.

The "double bubble" sign on X-ray (two air-filled structures representing the stomach and proximal duodenum) is the classic radiological finding of duodenal atresia. It is associated with Down syndrome (trisomy 21).

In portal hypertension, portal blood is diverted through paraumbilical veins (along the ligamentum teres/obliterated umbilical vein) to the superficial epigastric veins of the anterior abdominal wall, producing the radiating pattern of dilated veins (caput medusae) around the umbilicus.

The ligament of Treitz (suspensory muscle/ligament of the duodenum) marks the duodenojejunal flexure - the point where the duodenum transitions to the jejunum. It suspends this flexure from the right crus of the diaphragm and is a key surgical landmark.

The transverse cervical (Mackenrodt's/cardinal) ligament provides the primary passive support to the uterus and upper vagina. It runs from the cervix to the lateral pelvic walls. The uterosacral ligament provides posteroinferior support. The round ligament maintains anteversion but provides little structural support.

In extraperitoneal bladder rupture (most common type, usually from pelvic fracture), urine extravasates into the retropubic space (prevesical space/space of Retzius), which lies between the pubic symphysis anteriorly and the bladder posteriorly. Intraperitoneal rupture would fill the peritoneal cavity.

Normal bronchial epithelium is pseudostratified ciliated columnar (respiratory epithelium). Chronic smoking causes squamous metaplasia - replacement by squamous epithelium, which represents a pre-neoplastic change and can progress to squamous cell carcinoma.

This is Klinefelter syndrome (47, XXY). Classical features include tall stature, gynecomastia, small firm testes (hyalinization of seminiferous tubules), azoospermia, and low testosterone with elevated FSH/LH. It is the most common sex chromosome aneuploidy in males.

Tracheal deviation is away from the side of a tension pneumothorax. If the trachea deviates to the left, the tension pneumothorax is on the right side. The increased pressure in the right pleural cavity pushes mediastinal structures (including the trachea) to the left.

The left recurrent laryngeal nerve has a long intrathoracic course - it loops under the arch of the aorta (at the ligamentum arteriosum). Mediastinal masses (lymphoma, aortic aneurysm, lung cancer) frequently compress it, causing hoarseness. The right RLN loops around the right subclavian artery and is not in the mediastinum.

In right-dominant coronary circulation (present in ~70% of people), the right coronary artery (RCA) gives rise to the posterior interventricular (posterior descending) artery. This supplies the inferior wall of the left ventricle and the posterior interventricular septum.

The lienorenal (splenorenal) ligament connects the spleen to the left kidney and contains the splenic vessels (artery and vein) and the tail of the pancreas. The gastrosplenic ligament contains the short gastric and left gastroepiploic vessels.

The marginal artery of Drummond (Juxtacolic artery) is a continuous arterial arcade running along the inner margin of the large intestine from ileocolic to sigmoid, forming an anastomosis between the superior mesenteric artery and the inferior mesenteric artery. It is critically important as a collateral pathway in mesenteric ischemia.

The ischial spine is the key landmark for pudendal nerve block. The pudendal nerve crosses just medial to (or behind) the ischial spine as it exits the greater sciatic foramen and re-enters through the lesser sciatic foramen. Anesthetic is injected transvaginally or transperineally at this point for perineal analgesia (e.g., during labor).

Internal haemorrhoids occur above the pectinate line and are supplied by the superior rectal artery (terminal branch of the inferior mesenteric artery). They are true arteriovenous communications (hemorrhoidal cushions), and bright red bleeding is from the arterial supply - the superior rectal artery.

The sternal angle (angle of Louis) is the junction of the manubrium and body of the sternum. The 2nd costal cartilage articulates at this level, making the 2nd rib the key landmark for counting ribs. It also corresponds to the level of T4/T5 vertebrae, the bifurcation of the trachea, and the arch of the aorta.

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