364 APPLIED ANATOMY. 



FRACTURES OF THE HAND. 



Fractures of the carpal bones are often only suspected or detected by 

 means of a skiagraph. They are quite rare and are almost impossible to distinguish 

 clinically from ordinary sprains. 



Fractures of the metacarpal bones are more common. The bones are 

 subcutaneous on the dorsum of the hand and can be readily felt throughout their 

 entire length. They are not infrequently broken by a blow on the end of the bone 

 in fighting. Hamilton states that in every case in which the fracture has been pro- 

 duced by a blow on the knuckles the distal end of the distal fragment has been 

 drawn toward the palm and its proximal end projected toward the dorsum. This is 

 accounted for by the greater strength of the flexor muscles. 



The first, third, and fourth metacarpophalangeal joints have one extensor tendon, 

 the extensor communis digitorum. The second and fifth have in addition the extensor 

 indicis and the extensor minimi digiti. There are two powerful flexors, the sublimis 

 and profundus, and these are aided by the palmaris longus, interossei, and lumbri- 

 cales muscles. In one case Hamilton saw a dorsal projection of the proximal frag- 

 ment which he believed to be due to the action of the extensor carpi radialis muscle 

 because the deformity became less marked when the hand was bent backward and 

 the tendon relaxed. 



On anatomical grounds one would expect this dorsal displacement to occur 

 in fractures of the third metacarpal bone. It has only one carpal tendon inserting 

 into it, the extensor carpi radialis brevior. The second has the flexor carpi radialis 

 inserting on its palmar surface and the extensor carpi radialis longior on its dorsal 

 surface. 



The fifth metacarpal bone has the flexor carpi ulnaris on its palmar surface and 

 the extensor carpi ulnaris on its dorsal surface. Hence it would be expected that 

 the flexor and extensor muscles would neutralize each other. 



In order to relax the parts as well as to allow for the concavity of the palmar 

 surface of the metacarpal bones a rounded pad is to be placed in the palm and the 

 hand placed on a splint ; sometimes an additional flat pad and small dorsal splint is 

 of service. Care should be taken not to displace the fragments laterally by con- 

 stricting the hand with the bandage. 



Fractures of the Phalanges. These are frequently compound, necessitating 

 amputation. Fracture of the proximal phalanx necessitates a splint extending into 

 the hand, but for the middle and distal phalanges a short splint is sufficient. The 

 action of the interossei and lumbricales through their insertion into the extensor 

 tendon is liable to draw the distal fragment toward the dorsum if the fracture is 

 left untreated. 



A knowledge of the exact position of the joints is essential to avoid mistaking 

 fractures and dislocations for one another. 



WOUNDS OF THE HAND. 



Wounds of the hand, owing to the free blood supply, heal rapidly. An excep- 

 tion, however, is to be made in the case of the tendons. These frequently slough. 

 If the tendons are divided they are to be immediately united with sutures, otherwise 

 they retract into their sheaths. 



If nerves are divided where they are large, as near the wrist, they should be 

 sutured, because they are partly motor and supply the short muscles of the hand ; 

 but if the digital nerves are divided they need not be sutured as they are only sen- 

 sory. The median nerve enters the palm to the radial side of the median line, and 

 its position can be determined by following down the interval between the tendons of 

 the palmaris longus and flexor carpi radialis muscles. 



The ulnar nerve lies immediately to the radial side of the pisiform bone. 



Bleeding from wounds of the hand is not infrequently troublesome. The deep 

 arch may be injured in a wound about 2.5 cm. (i in.) below the lower crease on the 

 anterior surface of the wrist. Its position can also be approximately determined by 



