Proper palmar digital branches of median nerve

At a glance

English

Proper palmar digital branches of median nerve

Latin (TA2)

Rami digitales palmares proprii nervi mediani

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the proper palmar digital branches of median nerve

After passing through the carpal tunnel the median nerve widens and flattens, then divides into two parts, the lateral one smaller than the medial. The lateral part gives off the recurrent branch to the thenar muscles and then gives rise to three proper palmar digital nerves: two for the radial and ulnar sides of the thumb and one for the index finger's radial side, which also supplies the first lumbrical. The medial part gives two common palmar digital nerves. Of these, the first supplies the facing sides of index and middle fingers through two proper digital nerves, and the second does the same for the facing sides of the middle and ring fingers, and the lateral of these two common nerves also supplies the second lumbrical.

In the palm these nerves lie under the palmar aponeurosis and the superficial palmar arch, resting on the long flexor tendons. In the fingers each proper digital nerve runs along the side of the flexor tendon sheath, in front of and slightly to the palmar side of its digital artery, which is the reverse of the arrangement in the palm. Opposite the base of the proximal phalanx each nerve gives a dorsal branch that turns onto the back of the finger to supply the skin over the middle and distal phalanges, including the nail bed. At the tip the nerve divides into a branch for the pulp and another that spreads round and beneath the nail.

Together the branches carry touch, pain, temperature and position sense from the palmar surface of the lateral three and a half digits and from the backs of their ends. Losing it makes fine gripping clumsy. The index finger's radial border and the thumb pulp, used together in pinch, both depend on these nerves.

Cuts on the front of the fingers often divide a digital nerve, leaving one side of the finger numb; repair under magnification is usually advised. Nerves can also be squeezed by tight rings or bruised in bowling and other gripping activities. In carpal tunnel syndrome it is the territory of these branches, not the palm, that becomes numb. A digital nerve block, injecting anaesthetic at the base of the finger, relies on their predictable course along each side of the finger.

Course and supply

Arises from

From the lateral and medial divisions of the median nerve in the palm, directly or via the common palmar digital nerves.

Ends in

End in the pulp and nail bed of the thumb, index, middle and radial half of the ring finger.

Supplies

Sensory to the palmar skin of the lateral three and a half digits and the dorsal skin over their middle and distal phalanges; branches of the lateral nerves supply the first and second lumbricals.