Palmar aponeurosis
The central portion occupies the middle of the palm, is triangular in shape, and of great strength Its apex is continuous with the lower margin of the transverse carpal ligament, and receives the expanded tendon of the palmaris longus.The deeper part of each slip subdivides into two processes, which are inserted into the fibrous sheaths of the flexor tendons.By this arrangement short channels are formed on the front of the heads of the metacarpal bones; through these the flexor tendons pass.At the points of division into the slips mentioned, numerous strong, transverse fasciculi bind the separate processes together.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.