66 OUTLINES OF ANATOMY. 



Trace the branches of the brachial plexus through the region, or from their origin to the point 

 where they pass into or under other structures. The terminal distribution of each branch will be 

 demonstrated later, during the process of the dissection. 



' Branches of the brachial plexus : 



Branches given off above the clavicle, 834-5. (814-15) 

 Suprascapular nerve. Nerve to rhomboids. 

 Posterior thoracic nerve. Communicating twig to phrenic. 

 Nerve to subclavius. 

 Branches given off below the clavicle : 



Axillary or short branches, 835. (815-16) 

 External anterior thoracic. 

 Internal anterior thoracic. 

 Subscapular nerves : 



Upper or short subscapular nerve. 

 Middle or long subscapular nerve. 

 Lower subscapular nerve. 

 Terminal or long branches : 835. 

 From outer cord : 



Musculo-cutaneous and outer head of median. 

 From inner cord : 



Inner head of median. Ulnar. Internal cutaneous 

 and lesser internal cutaneous. 

 From posterior cord : 



Musculo-spiral and circumflex. 



The dissector of the tipper extremity should participate in the dissection of the back, 

 until the dissection of the serratus magnus is completed. (See pages 58, 59) 



The Shoulder. 



Note the distribution of the cutaneous nerves, Fig. 456; P. 836. (817) 



Remove the skin from the shoulder and the upper half of the arm, and expose the superficial fascia and 

 the nerves. 



Superficial fascia, 315. (318) 

 Superficial nerves: 



Supra-acromial branches, 831. (812) 



Cutaneous branches of the circumflex nerve, 835. (816) 

 Anterior division. Posterior division. 



Turn off the superficial fascia and expose the deep fascia. 



The deep fascia, 315. (318) 



Remove the deep fascia and expose the deltoid. 



Deltoid muscle, 316-17; Figs. 262 and 264. (318-19) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the deltoid at its origin and turn it down to the insertion. Note the vessels and nerves entering 

 its deep surface. 



Posterior circumflex artery, 557-8; Fig. 348. (547-8) 



Branches: Nutrient. Articular. Acromial. Muscular. 



Chief variations in the posterior circumflex. 



Circumflex nerve, 835. (816) 



Anterior division. Posterior division. 

 Anterior circumflex artery, 557. (546-7) 



Branches : Pectoral. Bicipital. 



Chief variations. 

 Turn off the deep fascia covering the infra- spinatus, teres, and supra- spinatus. 



Infra-spinatus, 317-18; Fig. 268. (319-20-1) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Teres minor, 319; Fig. 268. (321) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. 



