Radial nerve is the largest branch of the posterior cord of the brachial plexus with a root value of C5 - C8 and T1. The radial nerve is commonly injured in the region of the spiral groove. this result in the wrist drop and sensory loss over a narrow strip on the back of forearm, and on the lateral side of the dorsum of the hand. Posterior interosseous nerve is the branch of radial nerve given off in the cubital fossa while anterior interosseous nerve is a branch of the median nerve given off in the upper pa of the forearm. Skin of the back of the forearm (i.e. extensor compament) is supplied by the posterior cutaneous nerve of the forearm which is a branch of radial nerve.