Dorsum of the Hand Anatomy
The dorsum of the hand is innervated by branches of the radial and ulnar nerves (Fig. 3.78). The superficial branch of the radial nerve usually supplies the skin of the lateral three and one-half digits (excluding the nail beds) and a corresponding part of the dorsum of the hand. Skin of the dorsal aspect of the first web space is usually supplied exclusively by the radial nerve and is tested when radial nerve injury is suspected. The skin over the remainder of the posterior aspect of the hand and the medial one and one-half fingers (excluding the nail beds) is supplied by dorsal branches of the ulnar nerve that arise in the anterior compartment and pass around the medial aspect of the wrist.
Much of the venous blood from the digits and the palm drains into a network of vessels that often forms a superficial venous arch on the dorsum of the hand.
At the wrist, the tendons of extensor digitorum lie deep to the extensor retinaculum (Fig. 3.79), invested by a single synovial sheath. On the dorsum of the hand, the tendons diverge to reach the fingers.
Skin on the dorsum of the hand is elastic and freely mobile on the underlying loose connective tissue: infection or injury of the hand frequently results in swelling (oedema) of these lax tissues.