Palmar aponeurosis

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Palmar aponeurosis.
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The palmar aponeurosis
Details
Identifiers
Latin aponeurosis palmaris
TA A04.6.03.012
FMA 42435
Anatomical terminology

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

Contents

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.

At the points of division into the slips mentioned, numerous strong, transverse fasciculi bind the separate processes together.

The central part of the palmar aponeurosis is intimately bound to the integument by dense fibroareolar tissue forming the superficial palmar fascia, and gives origin by its medial margin to the palmaris brevis.

It covers the superficial volar arch, the tendons of the flexor muscles, and the branches of the median and ulnar nerves; and on either side it gives off a septum, which is continuous with the interosseous aponeurosis, and separates the intermediate from the collateral groups of muscles.

Lateral and medial portions

The lateral and medial portions of the palmar aponeurosis are thin, fibrous layers, which cover, on the radial side, the muscles of the ball of the thumb, and, on the ulnar side, the muscles of the little finger; they are continuous with the central portion and with the fascia on the dorsum of the hand.

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The flexor retinaculum of foot is a strong fibrous band, extending from the bony ankle prominence (malleolus) above, to the margin of the heelbone (calcaneus) below, converting a series of bony grooves in this situation into canals for the passage of the tendons of the flexor muscles and the posterior tibial vessels and tibial nerve into the sole of the foot.

Proper palmar digital nerves of median nerve Nerve

In the palm of the hand the median nerve is covered by the skin and the palmar aponeurosis, and rests on the tendons of the Flexor muscles. Immediately after emerging from under the transverse carpal ligament the median nerve becomes enlarged and flattened and splits into a smaller, lateral, and a larger, medial portion.

Common palmar digital nerves of median nerve

In the palm of the hand the median nerve is covered by the skin and the palmar aponeurosis, and rests on the tendons of the Flexor muscles. Immediately after emerging from under the transverse carpal ligament the median nerve becomes enlarged and flattened and splits into a smaller, lateral, and a larger, medial portion.

References

This article incorporates text in the public domain from page 460 of the 20th edition of Gray's Anatomy (1918)