It is present in the upper limb of human being and other animal. It is one of the 5 main nerves of brachial plexus. It is formed by medial and lateral cord of the brachial plexus. It continues down the arms and enters to the forearm with brachial artery. It originates from C_5, C_6, C_7, C_8, T₁ nerve roots. Median nerve is the only nerve which passes through the carpal tunnel where it may be compressed to cause carpal tunnel syndrome.

In the term, the course is cubital fossa. After receiving input from the lateral and medial cord of the brachial plexus the median nerve enters in the arm with brachial artery on the medial aspect of the arm between biceps brachii and brachialis. It then enters anteriorly to run medial to the brachial artery in the distal arm and enters to the cubital fossa. The median nerve gives up an articular branch in the cubital fossa and vascular branch to brachial artery in arm.

The median nerve arises from the cubital fossa and passes between the two heads of pronator teres. It then travels between the flexor digitorum superficialis and flexor digitorum profundus. Emerging between flexor superficialis and flexor pollicis longus. The median nerve innervates the muscles of superficial and intermediate groups of anterior compartment except flexor carpiulnaris.

The median nerve enters through the carpal tunnel deep to flexor retinaculum along with tendons flexor digitorum superficialis, flexor pollicis longus. In the hands, it gives up recurrent branches (million dollar nerve) to the thenar muscles. Here it provides the motor innervation to the opponens pollicis, flexor pollicis longus, abductor pollicis brevis and flexor pollicis brevis. It gives up digital branches to the lateral three fingers and half of the 4^th finger.

          Injury of median nerve at different level causes different syndromes. Injury of the nerve above the elbow joint results in loss of pronation, reduction in the flexion of hand at wrist. Lesion or compression of the median nerve can also leads to median nerve palsy. Injury by compression at carpal tunnel causes carpal tunnel syndrome.

In the hand thenar muscles are paralyzed and will atrophy with the passage of time. Opposition and flexors of the thumb and index finger are assisted in adduction and hyperextension. This appearance of the hand is known as Ape hand deformity.