1422 



CLINICAL AND TOPOGRAPHICAL ANATOMY 



18 mm. (f in.) above its extremity, where the narrow compact tissue is suddenly expanding 

 into cancellous. There is frequently impaction of the upper into the lower fragment. There 

 is a three-fold displacement of the lower fragment:- — (1) It is driven and drawn upward and 

 backward. (2) It is rotated so that its articular surface looks somewhat backward. (3) It 

 is drawn to the radial side. The chief causes of the discreditable stiffness often allowed to result 

 are non-reduction of the deformity, adhesions in the opened wrist-joint, teno-synovitis, and 

 prolonged immobilisation. 



Separation of epiphysis. — This may take place in the radius up to about the age of eighteen: 

 it is commoner before. Its possible importance in interfering with the symmetry of the growth 

 of the bones is obvious. Here, as in Colles' fracture, the level of the styloid processes of the 

 radius and ulna, and the correspondence of the two styloid processes of the radii, are important 

 in diagnosis. Exposure of the bones. In the case of ununited fracture or necrosis the radius 

 may be reached — (a) Behind, by an incision in a line drawn from the lateral epicondyle to the 

 back of the radius. The field opened here lies between the brachio-radialis and the radial 

 extensors on the one side, and the common extensor on the other. Care must be taken of the 



Fig 



1140. — DisTRiBrtTioN OF Cutaneous Nerves on the Anterior and Posterior Aspects 

 OF the Superior Extremity. 



Medial anti- 



brachial 



cutaneous 



Palmar cutaneous of 

 median 



Palmar cutaneous of 

 ulnar 



Supra-acromial 



Lateral brachial 



cutaneous 

 Intercosto- 



brachial 

 Twig of medial 



antibrachial 



cutaneous 



Dorsal 

 antibrachial 

 cutaneous 



Musculo- 

 cutaneous 

 (lateral anti- 

 brachial 

 cutaneous) 



Superficial 

 radial 



Lateral 



brachial 



cutaneous 



Dorsal anti- 

 brachial 

 cutaneous 



Musculo- 

 cutaneous 

 (lateral anti- 

 brachial 

 cutaneous) 



Superficial 

 radial 



Supraacromial 



Medial 

 brachial 

 cutaneous 

 (nerve of 

 Wrisberg) 



Medial anti- 

 brachial 

 cutaneous 



Ulnar 



deep radial (posterior interosseous) nerve, (b) In front. The incision here Lies in the sulcus 

 between the brachio radialis and the flexors. The pronator teres and the flexor subhmis must, 

 in part, be detached from the radius. If more room is required to reach an injured upper 

 extremity of the radius, the inci.sion will descend from above the lateral epicondyle in the groove 

 between the anconeus and common extensors. In the detachment of the supinator the deep 

 radial nerve will again need attention. The ulna is more easily reached by an incision between 

 the flexor and extensor carpi ulnaris. In removal of the lower part of the bones for myeloid 

 sarcoma or osteitis, the ulna is reached in the interval last mentioned. The radius is best 

 exposed by an inci.sion between the brachio-radialis and extensor carpi radialis longus, the super- 

 ficial radial nerve being the guide. (Morris.) Finally, the .so-called 'carrying angle' of the 

 forearm deserves mention. In extension the bones of the forearm are not in a straight line with 

 the humeruH, but directed .slightly laterally, the angle at the elbow-joint being obtuse, and open 

 laterally. This angle is so named from its facilitating carrying objects during walking. In 

 flexion the forearm is deflected somewhat toward the; middle lino, nu)uth, etc. Those properties 

 are liable to be lost under many and widely dilTorcnt conditions, of wliich injuries to the epijjhyses 

 of the humerus, badly united fractures of the forearm, and osteoarthritis of the elbow-joint are 

 instances. 



