THE UPPER LIMB 



331 



Supra-acromial 



which projects lower down than that of the ulna, and in front of it 

 is the radial artery. On the back of the radius, about its centre, 

 is the radial tubercle, which bounds externally the groove for the 

 tendon of the extensor longus pollicis. 



Olecranon Bursa. — ^This bursa is situated subcutaneously over 

 the posterior triangular surface 

 of the olecranon process of the 

 ulna. 



Cutaneous Nerves. — ^The inter- 

 costo - humeral nerve, having 

 crossed the axillary space, 

 ramifies in the integument of 

 the inner and back part of the 

 arm over its upper half. It 

 may be accompanied by an off- 

 set of the posterior branch of the 

 lateral cutaneous of the third 

 intercostal. 



The lesser internal cutaneous 

 or nerve of Wrisberg is dis- 

 tributed to the integument of 

 the inner side of the arm, as 

 low as the interval between 

 the internal epicondyle and 

 olecranon. 



The internal cutaneous nerve 

 furnishes one or more branches, 

 which, piercing the deep fascia 

 close to the axilla, are dis- 

 tributed to the integument over 

 the biceps. The nerve itself 

 pierces the deep fascia a little 

 below the centre of the arm, and 

 then divides into an anterior and 

 a posterior branch. The an- 

 terior branch descends behind 

 the median basilic vein, giving 

 one or two twigs over it, and 

 it is distributed„±o-theL integu- 

 ment of the^'anterior aspect of 

 the inner side of the forearm. 

 The posterior branch passes downwards and inwards on the inner 

 >ide of the basilic vein, and over the internal epicondyle, after 

 which it turns backwards to supply the integument over the back 

 of the inner side of the forearm. 



The internal cutaneous of the musculo-spiral is distributed to 

 the integument of the back of the arm, almost as low as the 

 olecranon. 



Cutaneous Branch of 



Circumflex 



Internal Cutaneous of 



Musculo spiral 



-- 'Intercosto-bumeral 



Lower External Cutaneous 



of Musculo-spiral 



Nerve of Wrisberg 



, -- Posterior Branch of Internal 

 Cutaneous 



Posterior Branch of Musculo- 

 cutaneous 



-Radial 



: Dorsal Bianch of Ulnar 



Fig. 18 



Diagram of the Cutaneous 

 Nerves of the Upper Limb 

 (Posterior Aspect). 



lO 





