Palmar aponeurosis

The palmar aponeurosis (palmar fascia) invests the muscles of the palm, and consists of central, lateral, and medial portions.

Structure

The central portion occupies the middle of the palm, is triangular in shape, and of great strength and thickness.

Its apex is continuous with the lower margin of the transverse carpal ligament, and receives the expanded tendon of the palmaris longus.

Its base divides below into four slips, one for each finger. Each slip gives off superficial fibers to the skin of the palm and finger, those to the palm joining the skin at the furrow corresponding to the metacarpophalangeal articulations, and those to the fingers passing into the skin at the transverse fold at the bases of the fingers.

The deeper part of each slip subdivides into two processes, which are inserted into the fibrous sheaths of the flexor tendons. From the sides of these processes offsets are attached to the transverse metacarpal ligament.

By this arrangement short channels are formed on the front of the heads of the metacarpal bones; through these the flexor tendons pass. The intervals between the four slips transmit the digital vessels and nerves, and the tendons of the lumbricales.