THE RADIUS 



193 



Appear* at 

 5th year: 



Hmd. Unites u-ith shaft 

 _ about 18th or 

 20th year. 



which take place in each hone individually. These fractures may be produced by either direct 

 or indirect violence, though more commonly by direct violence. When indirect force is applied 

 to the forearm the radius generally alone gives way, though both bones may suffer. The fracture 

 from indirect force generally takes place somewhere about the middle of the bones; fracture 

 from direct violence may occur at any part, more often, however, in the lower half of the bone. 

 The fracture is usually transverse, but may be more or less oblique. A point of interest in con- 

 nection with these fractures is the tendency that there is for the two bones to unite across the 

 interosseous membrane; the limb should therefore be put up in a position midway between supi- 

 nation and pronation, which is not only the most comfortable position, but also separates the bones 

 most widely from each other, and therefore diminishes 

 the risk of the bones becoming united across the inter- 

 osseous membrane. The splints, anterior and posterior, 

 which are applied in these cases should be rather wider 

 than the limb, so as to prevent any lateral pressure on 

 the bones. In these cases there is a greater liability to 

 gangrene from the pressure of the splints than in other 

 parts of the body. This is no doubt due principally to 

 two causes: (1) The flexion of the forearm compressing 

 to a certain extent the brachial artery and retarding 

 the flow of blood to the limb; and (2) the superficial 

 position of the two main arteries of the forearm in a 

 part of their course, and their liability to be compressed 

 by the splints. The special fractures of the ulna are: 



(1) Fracture of the olecranon. This may be caused by 

 direct violence, falls on the elbow with the forearm 

 flexed, or by muscular action by the, sudden contraction 

 of the triceps. The most common place for the frac- 

 ture to occur is at the constricted portion where the 

 olecranon joins the shaft of the bone, and the fracture 

 may be either transverse or oblique; but any part may 

 be broken, even a thin shell may be torn off. Fractures 

 from direct violence are occasionally comminuted. The 

 displacement is sometimes very slight, owing to the 

 fibrous structures around the process not being torn. 



(2) Fracture of the coronoid process sometimes occurs 

 as a complication of dislocation backward of the bones 

 of the forearm, but it is doubtful if it ever occurs as an 

 uncomplicated injury. (3) Fractures of the shaft of the 

 ulna may occur at any part, but usually takes place at the 

 middle of the bone or a little below it. They are usually 



the result of direct violence. (4) The styloid process may be knocked off by direct violence. 

 Fractures of the radius consist of: (1) Fracture of the head of the bone; this generally occurs 

 in conjunction with some other lesion, but may occur as an uncomplicated injury. (2) Fracture 

 of the neck may also take place, but is generally complicated with other injury. (3) Fractures of 

 the shaft of the radius are very common, and may take place at any part of the bone. They 

 may take place from either direct or indirect violence. In fractures of the upper third of the 

 shaft of the bone, that is to say, above the insertion of the Pronator teres, the displacement is 

 very great. The upper fragment is strongly supinated by the Biceps and Supinator, and flexed 

 by the Biceps, while the lower fragment is pronated and drawn toward the ulna by the two 

 pronators. If such a fracture is put up in the ordinary position, midway between supination 

 and pronation, the fracture will unite with the upper fragment in a position of supination, and 

 the lower one in the mid-position, and thus considerable impairment of the movements of the 

 hand will result. The limb should be put up with the forearm supinated. (4) The most impor- 

 tant fracture of the radius is that of the lower end (Colics' fracture). The fracture is transverse, 

 and generally takes place about an inch from the lower extremity. It is caused by falls on the 

 palm of the hand, and is an injury of advanced life, occurring "more frequently in the female 

 than the male. In consequence of the manner in which the fracture is caused, the upper frag- 

 ment becomes driven into the lower, and impaction is the result; or else the lower fragment 

 becomes split up into two or more pieces, so that no fixation occurs. Separation of the lower 

 epiphysis of the radius may take place in the young. This injury and Colics' fracture may be 

 distinguished from other injuries in this neighborhood especially dislocation, with which 'it is 

 liable to be confounded by observing the relative positions of the styloid processes of the ulna 

 and radius. In the natural condition of parts, with the arm hanging by the side, the styloid 

 process of the radius is on a lower level than that of the ulna; that is to say, nearer the ground. 

 After fracture or separation of the epiphysis this process is on the same or a higher level than that 

 of the ulna, whereas it would be unaltered in position in dislocation. 



13 



Appears o<_ 

 2d year. 



Unites with shaft 

 about 20th year. 



Lower extremity. 



FIG. 149. Plan of the development of the 

 radius. From three centres. 



