502 



In fracture of the shaft of the ulna 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 surfaces 

 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 supination, 

 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 fragment 

 of the radius is drawn upward and inward by the Biceps and Pronator 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 (Colles' fracture) (Fig. 377) the displacement which 

 is produced is very considerable, and bears some resemblance to dislocation of the carpus back- 

 ward, from which it should be carefully distinguished. The lower fragment is displaced back- 

 ward 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 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 sufficient extension, when crepitus may be occasionally detected; at the same time, 

 on extension being discontinued, the parts immediately resume their deformed appearance. 

 The age of the patient will also assist in determining whether the injury is fracture or separation 

 of th" epiphysis. Reduction is effected by hyperextension, longitudinal traction, and forced 

 flexion. 1 The posterior straight splint with suitable pads is the best dressing. 



MUSCLES AND FASCLffi OF THE LOWER EXTREMITY. 



The muscles of the lower extremity are subdivided into groups corresponding 

 with the different regions of the limb. 



I. ILIAC REGION. 2. Internal Femoral Region. 



Psoas magnus. Gracilis. 



Psoas parvus. Pectineus. 



Iliacus. Adductor longus. 



Adductor brevis. 



Adductor magnus. 



II. THIGH. IIL Hlp - 



V 3. Gluteal Region. 



1. Anterior Femoral Region. 



(jrluteus maximus. 



Glutens medius. 



Tensor fasciae femoris. Gluteus. minimus. 



Sartorius. Pyriformis. 



Quadriceps 

 extensor. 



Rectus femoris. / Obturator internus. 



Vastus externus.^ Gemellus superior. 



Vastus internus. V Gemellus inferior. 



Crureus. Quadratus femoris. 



Subcrureus. Obturator externus. 



i R. J. Levis. 



