the terminal section of the upper extremity (arm) in man, capable of performing extremely delicate and differentiated movements.
The hand consists of the carpus, the metacarpus, and the digits. Of the eight bones of the carpus, which are arranged in two rows, three articulate with the bones of the forearm (the radiocarpal joint) and with those of the metacarpus, which make up the base of the hand. The basal phalanges of the fingers articulate with the metacarpal bones.
The fingers have great mobility. The first digit, or thumb, can be opposed to the remaining four digits. This is especially important for grasping and holding objects. Movement of the hand and fingers is made possible by muscles located both in the hand itself and in the forearm. The tendons of the hand muscles pass through the bone-fiber canals and are surrounded by sheaths that are longer in the first and fifth digits.
The muscles that move the hand and fingers are innervated by branches of the ulnar, radial, and median nerves. The hand receives its blood supply from the radial and ulnar arteries, which form deep and superficial arterial arches and plexuxes on the hand’s palmar surface. The deep and superficial venous networks pass into the antebrachial veins.