Radial neuropathy.

The radial nerve is the largest branch of the brachial plexus, and is commonly involved in upper extremity mononeuropathies. The radial nerve is primarily responsible for motor innervation of the upper extremity extensors, as well as receiving cutaneous innervation from most of the posterior arm, forearm, and hand. There are a variety of sites at which the radial nerve is susceptible to trauma and entrapment. Localizing radial nerve lesions is dependent on clinical knowledge of radial nerve anatomy, and sensory and motor examination.