54 



THE UPPER EXTREMITY 



Dissection. The branches of the posterior circumflex artery of the 

 humerus and the axillary nerve should now be dissected out on the deep 

 surface of the deltoid muscle. 



Arteriae Circumflexae Humeri (O.T. Circumflex Arteries). 



The arteria circumflexa humeri posterior has been already 

 observed to arise within the axilla from the posterior aspect 

 of the axillary artery a short distance distal to the subscapular 

 branch. It at once proceeds backwards, through the quadri- 

 lateral space, and, winding round the surgical neck of the 

 humerus, it is distributed in numerous branches to the deep 

 surface of the deltoid muscle. Several twigs are also given to 

 the shoulder-joint and the integument. It anastomoses with 



H. Transverse section of the 

 humerus immediately be- 

 low the tuberosities. 

 A. A. Axillary artery. 

 P.C. Posterior circumflex artery. 

 A.C. Anterior circumflex artery. 

 C.-'V. Axillary nerve. 



a. Articular branch. 

 T.M. Branch to teres minor. 

 C. Cutaneous branches. 



FIG. 23. Diagram of the Circumflex Vessels and Axillary Nerve. 



the acromial branch of the thoraco-acromial artery and the art. 

 circumflexa humeri anterior, and also, by one or more twigs 

 which it sends distally to the long head of the triceps, with 

 thejprofunda branch of the brachial artery. 



The termination of the arteria circumflexa humeri anterior 

 can now be more satisfactorily studied, and its anastomosis 

 with the art. circumflexa humeri posterior established if the 

 injection has flowed well. By this anastomosis the arterial 

 ring which encircles the proximal part of the humerus is 

 completed. 



Nervus Axillaris (O.T. Circumflex Nerve). This nerve 

 accompanies the posterior circumflex artery, and supplies 

 (a) muscular branches to the deltoid and teres minor ; (b) 

 cutaneous branches to the skin over the distal part of the 

 deltoid ; and (c) an articular twig to the shoulder-joint. The 



