Digital nerves of hand

Lying immediately deep to the superficial palmar arch are the common palmar digital nerves. They pass distally to the webs, between the slips of the palmar aponeurosis and divide like the arteries into proper palmar digital nerves. Here the nerves lie superficially; they are destined essentially for the sensitive pads at the fingertips. They end dorsally by supplying all five nail beds. The digital arteries, lying dorsal to the digital nerves along the fingers, are directed towards the nail bed, where they are free from the pressure of gripping.

The superficial branch of the ulnar nerve divides into two branches; the medial one supplies the ulnar side of the little finger, the lateral the cleft and adjacent sides of little and ring fingers.

The median nerve enters the palm beneath the flexor retinaculum and divides into three branches. The medial branch divides into two and supplies the cleft and adjacent sides of ring and middle fingers and the cleft and adjacent sides of middle and index fingers. The latter branch supplies the second lumbrical muscle. The lateral branch supplies the radial side of the index, the whole of the thumb and its web on the palmar surface and distal part of the dorsal surface. The branch to the index supplies the first lumbrical.

The highly important muscular (recurrent) branch curls upwards from around the distal border of the flexor retiĀ­naculum to supply the thenar muscles. To reach these muscles the nerve passes superficial to the tendon of flexor pollicis longus. Incision of the sheath will endanger the nerve if the cut is not kept sufficiently distal.