MRCS Part A Anatomy Syllabus

Which muscles make up the quadriceps femoris and what is their action and innervation?

Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius. They extend the knee (rectus femoris also flexes the hip); innervated by the femoral nerve (L2–L4).

Name the three hamstring muscles and their common innervation.

Biceps femoris, semitendinosus, semimembranosus. They flex the knee and extend the hip; innervated by the tibial division of the sciatic nerve (biceps short head by the common fibular division).

What are the boundaries of the femoral triangle?

Superior: inguinal ligament; lateral: sartorius; medial: adductor longus. Contents (lateral to medial): femoral Nerve, Artery, Vein, and Canal/lymphatics (NAVEL).

Which nerve is injured with fibular neck fractures, and what is the resulting deficit?

The common fibular (peroneal) nerve, causing foot drop — loss of dorsiflexion and eversion — and sensory loss over the dorsum of the foot.

What are the two terminal branches of the sciatic nerve and their broad motor territories?

Tibial nerve (posterior compartment of leg / plantar foot — plantarflexion) and common fibular nerve (anterior and lateral leg — dorsiflexion and eversion).

Trace the main arterial supply of the lower limb from the external iliac artery.

External iliac → femoral (at inguinal ligament) → popliteal (at adductor hiatus) → anterior tibial and posterior tibial (which gives the fibular artery) → dorsalis pedis and plantar arteries.

Where is the dorsalis pedis pulse palpated?

On the dorsum of the foot, lateral to the extensor hallucis longus tendon, between the 1st and 2nd metatarsal bases; it is the continuation of the anterior tibial artery.

How many true, false, and floating ribs are there?

12 pairs total: ribs 1–7 are 'true' (attach directly to the sternum via costal cartilage), ribs 8–10 are 'false' (attach indirectly via the cartilage above), and ribs 11–12 are 'floating' (no anterior attachment).

What is the sternal angle (angle of Louis) and its significance?

The palpable manubriosternal joint at the level of the 2nd costal cartilage. It marks the T4/T5 disc level, the bifurcation of the trachea, the start/end of the aortic arch, and the division between superior and inferior mediastinum.

Name the muscles of the thoracic wall involved in respiration and their basic actions.

External intercostals (elevate ribs — inspiration), internal and innermost intercostals (depress ribs — forced expiration), and the diaphragm (chief muscle of inspiration).

What is the arrangement of the neurovascular bundle in an intercostal space?

In the costal groove of each rib, ordered superior to inferior as Vein, Artery, Nerve (VAN). Chest drains/needles are inserted just above the lower rib to avoid the bundle.

Which structures pass through the diaphragm and at what vertebral levels?

IVC at T8 (caval opening), oesophagus with vagi at T10 (oesophageal hiatus), aorta with thoracic duct and azygos vein at T12 (aortic hiatus). Mnemonic: 'I ate ten eggs at twelve.'

Describe the surface anatomy relationship of the trachea's bifurcation.

The trachea bifurcates into the right and left main bronchi at the carina, at the level of the sternal angle (T4/T5). The right main bronchus is wider, shorter, and more vertical, so aspirated objects lodge there.

Compare the right and left lungs in terms of lobes and fissures.

Right lung: 3 lobes (upper, middle, lower), oblique and horizontal fissures. Left lung: 2 lobes (upper, lower), oblique fissure only, with a cardiac notch and lingula on the upper lobe.

Name the four chambers and the valves of the heart.

Right atrium, right ventricle, left atrium, left ventricle. Valves: tricuspid (RA→RV), pulmonary (RV→pulmonary trunk), mitral/bicuspid (LA→LV), aortic (LV→aorta).

What are the three subdivisions of the mediastinum's inferior part?

Anterior mediastinum (thymus remnants), middle mediastinum (heart and pericardium, great vessel roots), and posterior mediastinum (oesophagus, thoracic aorta, azygos system, thoracic duct).

What does the vagus nerve supply in the thorax and where does the left recurrent laryngeal branch loop?

The vagus (CN X) provides parasympathetic supply to the heart, lungs, and oesophagus. The left recurrent laryngeal nerve loops under the arch of the aorta; the right loops under the right subclavian artery.

What is the sympathetic supply of the thorax and where is the sympathetic chain located?

The sympathetic trunk runs vertically alongside the vertebral bodies (over the rib heads); thoracic splanchnic nerves (greater T5–9, lesser T10–11, least T12) carry presynaptic fibres to abdominal ganglia.

What is a dermatome, and which dermatomes are useful thoracic landmarks?

A dermatome is the skin area supplied by a single spinal nerve. Landmarks: T4 at the nipple, T6 at the xiphoid, T10 at the umbilicus.

Name the three branches of the arch of the aorta in order.

Brachiocephalic (innominate) trunk, left common carotid artery, and left subclavian artery.

Describe the azygos venous system's role in the thorax.

The azygos vein (right) and hemiazygos/accessory hemiazygos (left) drain the posterior thoracic wall and provide a collateral route between the superior and inferior vena cava; the azygos arches over the right lung root to join the SVC.

Name the layers of the anterolateral abdominal wall muscles from superficial to deep.

External oblique, internal oblique, transversus abdominis (laterally), and rectus abdominis (anteriorly, within the rectus sheath).

What structures pass through the inguinal canal in males and females?

Males: the spermatic cord (with vas deferens, testicular vessels). Females: the round ligament of the uterus. The ilioinguinal nerve traverses part of the canal in both.

Distinguish direct from indirect inguinal hernias.

Indirect: passes through the deep inguinal ring, lateral to the inferior epigastric vessels, into the canal (congenital, more common). Direct: pushes through the weak posterior wall (Hesselbach's triangle), medial to the inferior epigastric vessels (acquired).

What are the boundaries of Hesselbach's (inguinal) triangle?

Lateral: inferior epigastric vessels; medial: lateral border of rectus abdominis; inferior: inguinal ligament. Direct inguinal hernias emerge through it.

Define the peritoneum and distinguish intraperitoneal from retroperitoneal organs.

The peritoneum is a serous membrane lining the abdominal cavity. Intraperitoneal organs (e.g. stomach, small intestine, spleen) are suspended by mesentery; retroperitoneal organs (e.g. kidneys, aorta, pancreas, duodenum parts) lie behind the parietal peritoneum. Mnemonic SAD PUCKER.

What are the three unpaired midline branches of the abdominal aorta and the organs they supply?

Coeliac trunk (T12) — foregut (stomach, liver, spleen, proximal duodenum); superior mesenteric artery (L1) — midgut (distal duodenum to proximal 2/3 transverse colon); inferior mesenteric artery (L3) — hindgut (distal colon to upper rectum).

Describe the arterial supply and portal drainage relevant to the liver.

Dual supply: hepatic artery proper (~25%, oxygenated) and hepatic portal vein (~75%, nutrient-rich from the gut). Venous drainage is via hepatic veins into the IVC.

What forms the hepatic portal vein and why is it clinically important?

It is formed behind the neck of the pancreas by the union of the superior mesenteric vein and the splenic vein (which receives the inferior mesenteric vein). Portal hypertension causes varices at portosystemic anastomoses (oesophageal, rectal, umbilical/caput medusae).

Name the nerves of the abdominal wall and posterior abdomen and their spinal origins.

Anterior wall: thoraco-abdominal nerves (T7–T11), subcostal (T12), iliohypogastric and ilioinguinal (L1). Posterior (lumbar plexus): genitofemoral (L1–2), lateral femoral cutaneous (L2–3), femoral (L2–4), obturator (L2–4).

What is the coeliac (solar) plexus and its function?

A large autonomic nerve plexus around the origin of the coeliac trunk, formed by sympathetic (greater/lesser splanchnic) and parasympathetic (vagal) fibres; it supplies the foregut viscera and can be blocked to relieve upper abdominal pain (e.g. pancreatic cancer).