J ) ti/in of Ham/ 269 



of these muscles form a prominence on the back of the lower third of 

 the radius. Then comes the ' anatomist's snuff-box,' in the depths of 

 which are the tendons of the radial extensors, and on the inner side 

 of which descends the oblique tendon of the extensor secundi. Still 

 more internally pass the tendons of the extensor communis. The 

 radial styloid process descends considerably lower than that of the 

 ulna (p. 283). 



At \hzfront of the wrist, between the lower end of the radius and 

 the root of the thumb, are the prominence of the scaphoid and the 

 ridge of the trapezium, and on the inner side, behind the movable 

 pisiform, is the cuneiform. (See fig. on p. 286.) 



On the back of the Jiand zcce seen the venous arches from which the 

 radial and posterior ulnar veins ascend. The spaces between the 

 metacarpal bones are filled by the dorsal interosseous muscles ; the 

 chief of these is the abductor indicis, which, together with the adductor 

 pollicis, makes the thick mass between the first and second metacarpal 

 bones. When the ulnar nerve is paralysed these muscles waste and 

 the bones become strangely prominent. 



At the front of the first metacarpo-phalangeal joint can be felt the 

 sesamoid bones in the heads of insertion of the flexor brevis pollicis. 



In the ball of the thumb are the abductor, opponens, and the super- 

 ficial head of the flexor brevis pollicis, and in the ball of the little 

 finger are the abductor, flexor brevis, and opponens minimi digiti. 



For the sake of strength and protection, the palm of the hand is 

 continued a short distance beyond the bases of the first row of 

 the phalanges. 



The transverse creases of the palm. If you gently flex the 

 fingers to the palm you will see a thick ruck of integument stand out 

 across the level of the metacarpo-phalangeal joints. This ruck is 

 bounded below by the short transverse furrows at the roots of the 

 fingers, and above by two well-marked creases which together stretch 

 right across the palm. The inner of these creases stands across the 

 heads of the fifth, fourth, and third metacarpal bones, the outer and 

 superior across the head of the index metacarpal bone. This second 

 crease would not be needed were all the metacarpal bones of the same 

 length ; but, the index metacarpal being shorter than the middle, a 

 fresh crease has to be started in the outer part of the palm. 



If the skin and the subjacent soft parts of the palm were but a thin 

 layer, the transverse crease would correspond exactly to the line of 

 the metacarpo-phalangeal joint ; as it is, however, its thickness entails 

 a double crease, in order that the fingers may be bent. This ruck of 

 skin and fat plays a useful part in the hand of the oar's-man, cricketer, 

 and labouring man, shielding the heads of the metacarpal bones from 

 pressure ; the firmer the grasp, the thicker becomes the transverse pad. 



When one understands the reason of the appearance of the trans- 

 verse fold of skin and fat, and appreciates its usefulness, one realises 



