The radial nerve originates as a terminal branch of the
posterior cord of the
brachial plexus. The radial nerve gives out muscular branches to supply the long head, medial head, and lateral head of triceps brachii muscles before and during its course in the radial sulcus. After it emerges out from the radial sulcus, it supplies the
brachialis,
brachioradialis and
extensor carpi radialis longus. • The
superficial branch of the radial nerve is widely separated from the
radial artery in the upper one third of the forearm, closely related to
radial artery in the middle third of the forearm, and in the lower third, it descends in the forearm under the tendon of
brachioradialis. It crosses brachioradialis to enter posterior of forearm near the back of the wrist and supply dorsum of hand. It gives sensory supply to dorsal aspect of hand, dorsal aspect of thumb, index finger, middle finger and lateral side of ring finger except the nail beds, which are supplied by proper digital branches of
median nerve.) pierces the
supinator muscle, winds around the radius under the cover of supinator to reach posterior of forearm where it again pierces supinator and after which it is known as the
posterior interosseous nerve. It pierces the posterior extensor muscles and comes to lie between superficial and deep muscles of the back of the forearm. At the lower border of
extensor pollicis brevis, it passes deep to the
extensor pollicis longus and then run on the posterior interosseous membrane. It continues to move along with
posterior interosseous artery (a deep branch of
common interosseous artery which is a branch of
ulnar artery), and ends as a
pseudoganglion below
extensor retinaculum by supplying the wrist and
intercarpal joints. ==Function==