THE HAND 81 



and crepitus are difficult to obtain, as it is not easy to fix the 

 proximal fragment, owing to its small size. This fracture was 

 difficult to recognise before the introduction of X-rays and was 

 frequently mistaken for a sprain of the carpo-metacarpal joint. 



The whole of the radial border and most of the dorsal surface 

 of the Second Metacarpal can be readily examined ; its enlarged 

 base forms a prominence on the back of the hand. 



The dorsal surfaces of the Third, Fourth, and Fifth 

 Metacarpals are obscured by the extensor tendons, but the 

 Styloid Process on the base of the third can be felt about two 

 fingers' breadths directly distal to the dorsal radial tubercle 

 (p. 66) ; the tendon of the extensor carpi radialis brevis is 

 attached to it. On the ulnar border of the hand, the tendon 

 of the extensor carpi ulnaris can be traced to its insertion into 

 the base of the fifth metacarpal. 



Fractures of the metacarpal bones, when produced by direct 

 violence, are transverse and show little displacement. When 

 they follow indirect violence, they tend to be oblique, and the 

 distal fragment is generally displaced proximally and backwards, 

 causing a slight shortening of the corresponding finger. 



The prominences of the knuckles are produced by the heads 

 of the metacarpal bones. The dorsal groove corresponding to 

 each metacarpo-phalangeal joint lies one-third of an inch distal 

 to the head of each metacarpal. On the palmar aspect the 

 joint corresponds to the lower skin crease of the palm and lies 

 three-quarters of an inch from the edge of the web of the fingers. 



The dorsal line of each proximal inter-phalangeal joint lies 

 one-sixth of an inch distal to the prominence of the head of the 

 first phalanx, and corresponds, on the palmar aspect, to the 

 most proximal skin crease at the joint. The dorsal line of 

 each distal inter-phalangeal joint lies one-twelfth of an inch 

 distal to the prominence formed by the head of the second 

 phalanx and corresponds, on the palmar surface, to the most 

 distal skin crease at the joint. 



The Superficial Fascia of the palm is rendered extremely 

 tough by the presence of numerous fibrous septa, which connect 

 the deep surface of the skin to the palmar aponeurosis (deep 

 palmar fascia). On this account pus does not accumulate in 

 any quantity in this situation, but makes its way through the 

 cutis vera and collects under the epidermis as a purulent blister. 

 Over the terminal phalanges the superficial fascia forms fatty 

 pads, which are connected to the periosteum by fibrous septa. 



