Eponymous: giving one's name to something, as to an institution or a clinical sign (from the Greek, ‘epi’ meaning to, and ‘onoma’ meaning name).

Achilles' tendon: the combined tendon of the gastrocnemius and soleus muscles of the leg. It joins the calf muscles to the calcaneum. From mythology it was the only part of Achilles’ body that was still at risk after his mother had dipped him holding him by his heel into the river Styx.

Artery of Adamkiewicz: the largest of the medullary arteries which supply the spinal cord by anastomizing with the anterior spinal artery. Injury to this artery can result in ischaemia of the lower spinal cord – anterior spinal syndrome.

Adson's test: a test for thoracic outlet syndrome. The radial pulse is palpated and the patient's head turned to the opposite side of the arm being examined on deep inspiration. In the presence of compression of the thoracic outlet such as a cervical rib, the radial pulse will disappear.

Allen's test: tests the arterial supply to the hand which involves compression and release of radial and ulnar vessels and observation of colour change. Should be used prior to taking arterial blood gas samples from the radial artery or inserting an arterial line into this vessel.

Amyand's hernia: an inguinal hernia involving the appendix.

Amyrand's triangle: a diagrammatic triangular representation of the concentration of the constituents responsible for gallstone formation (bile salts, phospholipids and cholesterol).

Angle of Louis: the angle formed between the junction of the manubrium and the body of the sternum lies at the level of T4.