414 



THE MUSCLES AND FASCIAE. 



FIG. 250. Fracture of the shaft of the radius. 



a position of supination, otherwise union will take place with great impairment of the move- 

 ments of the hand. In fractures of the radius below the insertion of the Pronator radii teres 



(Fig. 250), the upper fragment is drawn up- 

 ward by the Biceps and inward by the Pro- 

 nator radii teres, holding a position midway 

 between pronation and snpination, and a de- 

 gree of fulness in the upper half of the lore- 

 arm is thus produced : the lower fragment is 

 drawn downward and inward inward the ulna 

 by the Pronator quadratus. and thrown into a 

 state of pronation by the same muscle ; at the 

 same time, the Supinator longus. by elevating 

 the styloid process, into which it is inserted. 

 will serve to depress the upper end of the 

 lower fragment still more toward the ulna. 

 In order to relax the opposing muscles the 



forearm should be bent, and the limb placed in a position midway between pronation and 

 supination; the fracture is then easily reduced by extension from the wrist and elbow: well- 

 padded splints should be applied on both sides of the forearm from the elbow to the wrist ; 

 the hand being allowed to fall, will, by its own weight, counteract the action of the Pronator 

 quadratus and Supinator longus, and elevate the lower fragment to the level of the upper 

 one. 



In fracture of the shaft of the uhta the upper fragment retains its usual position, but the 

 lower fragment is drawn outward toward the radius by the Pronator quadratus. producing a 

 well-marked depression at the seat of fracture and some fulness on the dorsal and palmar sur- 

 faces of the forearm. The fracture is easily reduced by extension from the wrist and forearm. 

 The forearm should be flexed, and placed in a position midway between pronation and supina- 

 tion, and well-padded splints applied from the elbow to the ends of the fingers. 



In fracture of the. shafts of the radius and ulna together the lower fragments are drawn 

 upward, sometimes forward, sometimes backward, according to the direction of the fracture, by 

 the combined actions of the Flexor and Extensor muscles, producing a degree of fulness on the 

 dorsal or palmar surface of the forearm ; at the same time the two fragments are drawn into 

 contact by the Pronator quadratus, the radius being in a state of pronation : the upper frag- 

 ment of the radius is drawn upward and inward by the Biceps and Pronator radii teres to a 

 higher level than the ulna ; the upper portion of the ulna is slightly elevated by the Brachialis 

 anticus. The fracture may be reduced by extension from the wrist and elbow, and the forearm 

 should be placed in the same position as in fracture of the ulna. 



In fracture of the lower end of the radius (Fig. 251) the displacement which is produced 

 is very considerable, and bears some resemblance to dislocation of the carpus backward, from 

 which it should be carefully distinguished. The lower fragment is displaced backward and 

 upward, but this displacement is probably due to the force of the blow driving the portion of 

 the bone into this position and not to any muscular influence. The upper fragment projects 

 forward, often lacerating the substance of the Pronator quadratus, and is drawn by this muscle 

 into close contact with the lower end of the ulna, causing a projection on the anterior surface of 



FIG. .51. Fracture of the lower end of the radius. 



the forearm, immediately above the carpus, from the flexor tendons being thrust forward. This 

 fracture may be distinguished from dislocation by the deformity being removed on making suf- 

 ficient extension, when crepitus may be occasionally detected ; at the same time, on extension 

 being discontinued, the parts immediately resume their deformed appearance (see also page 

 128). The age of the patient will also assist in determining whether the injury is fracture or 

 separation of the epiphysis. The treatment consists in flexing the forearm, and making power- 

 ful extension from the wrist and elbow, depressing at the same time the radial side of the hand, 

 and retaining the parts in that position by well-padded pistol-shaped splints. 



