Median nerve in the context of "Carpal bones"

The brachial artery is the major blood vessel of the (upper) arm. It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries which run down the forearm. In some individuals, the bifurcation occurs much earlier and the ulnar and radial arteries extend through the upper arm. The pulse of the brachial artery is palpable on the anterior aspect of the elbow, medial to the tendon of the biceps, and, with the use of a stethoscope and sphygmomanometer (blood pressure cuff), often used to measure the blood pressure.

The brachial artery is closely related to the median nerve; in proximal regions, the median nerve is immediately lateral to the brachial artery. Distally, the median nerve crosses the medial side of the brachial artery and lies anterior to the elbow joint.

In the human body, the carpal tunnel or carpal canal is a flattened body cavity on the flexor (palmar/volar) side of the wrist, bounded by the carpal bones and flexor retinaculum. It forms the passageway that transmits the median nerve and the tendons of the extrinsic flexor muscles of the hand from the forearm to the hand. The median artery is an anatomical variant (increasingly found). When present it lies between the radial artery, and the ulnar artery and runs with the median nerve supplying the same structures innervated.

When swelling or degeneration occurs in the tendons and sheaths of any of the nine flexor muscles (flexor pollicis longus, four flexor digitorum profundus and four flexor digitorum superficialis) passing through the carpal tunnel, the canal can narrow and compress/entrap the median nerve, resulting in a compression neuropathy known as carpal tunnel syndrome (CTS). If untreated, neuropraxia, parasthesia and muscle atrophy (especially of the thenar muscles) can occur. The condition often requires surgical division of the retinaculum to relieve the pressure upon the nerve.