Wrist, Hand and Foot LO 3
3. Describe the neurovascular supply to the hand.
The sensory innervation is described above. The motor innervation of the intrinsic hand muscles is primarily from the ulnar nerve; remember that most of the forearm muscles also act on the hand and are innervated as described in the previous sessions.
Most all of the intrinsic hand muscles are innervated by the ulnar n. except the three thenar muscles. The three thenar muscles are innervated by an efferent branch from the median n. – the recurrent branch of median n. This nerve branches from the median after the median n. passes through the carpal tunnel into the hand.
The hand is supplied by an abundance of anastomosing arteries that are derived from the radial and ulnar aa. This collateral supply ensures that the blood reaches the hand regardless of the various positions and pressures it endures. The ulnar a. enters the hand lateral to the ulnar n. It branches into superficial and deep branches to form superficial & deep palmar arches. There is a reliable pulse point as the ulnar passes across the wrist just lateral to the tendon of the flexor carpi ulnaris. The radial a. crosses the wrist at the scaphoid bone and curves onto the dorsal side of the lateral hand. It passes across the floor of the “anatomical snuff box.” The radial a. dives through the muscle tissue between the thumb and first finger to form the deep palmar arch on the palmar side by anastomosing with the deep branch of the ulnar a. Commonly, before the radial artery curves onto the dorsum of the hand, then it gives off a superficial branch that anastomoses with the superficial branch of the ulnar artery to form the superficial palmar arch.