The hand is the part of the body which terminates the arm, and consists of the palm and fingers, connected with the arm at the wrist. The human hand is comprosed of twenty-seven bones, namely eight bones of the carpus or wrist arranged in two rows of four each, the row next to the fore-arm containing the scaphoid, the semilunar, the cuneiform, and the pisiform, and next the metacarpus, the trapezium, the trapezoid, the osmagnum and the unciform. The metacarpus consists of the five bones which form the palm, the first being that of the thumb, the others that of the fingers in succession. Lastly, the fingers proper contain fourteen bones called phalanges, of which the thumb has but two, all the other digits having three each. These bones are jointed so as to admit a variety of movements, the more peculiar being those by which the hand is flexed backwards, forwards and sideways, and by which the thumb and fingers are moved in different ways.
The chief muscles which determine these movements are the flexors, which pass down the fore-arm, are attached by tendons to the phalanges of the fingers and serve to flex or bend the fingers; and the extensors for extending the fingers. There are two muscles which flex all the fingers except the thumb. The thumb has a separate long and short flexor. There is a common extensor for the fingers which passes down the back of the fore-arm and divides at the wrist into four tendons, one for each finger, each being attached to all three phalanges. The forefinger and little finger have, in addition, each an extensor of its own, and the thumb has both a short and a long extensor. The tendons of the muscles of the hand are interlaced and bound together by bands and aponeurotic fibres, and from this results a more or less complete unity of action.
Abbreviations
Research Unciform
