SHOULDER, ARM, FOREARM, AND HAND. 



189 



8. Contents. Axillary connective tissue and glands ; the axillary artery 

 and vein and their branches ; the large branches of the brachial plexus. 



9. The posterior boundary is formed by the subscapular, teres major, and latis- 

 simus dorsi muscles. 



The cephalic vein and descending branch of the acromio-thoracic artery. 

 The vein (Fig. 105) is the guide to the groove. The groove is the boundary- 

 line between the clavicular origins of the pectoralis major and deltoid muscles. 

 The vein opens into the subclavian. 



The Pectoralis Major Muscle. Remove the skin and find in the super- 

 ficial fascia two cutaneous nerves the supraclavicular and suprasternal ; the 

 one supplying the skin over the deltoid is the supraacromial. These are the 

 descending branches from the superficial part of the cervical plexus. 



Subclavius muscle 



First Rib 



CUT END OF CLAVICLE 



Costo-coracoid 

 ligament 



Cephalic rein 



. I rroin io-thoraeic artery 



Xti/H-riii 1 ' flinnii-ic ai-ten/ 

 Clavi-pectoral fascia 



l>n*TI-:RIOR THOR- 

 ACIC .VAY.M7-; 



FIG. 132. THE CLAVI-PECTORAL FASCIA. 



The deltoid aponeurosis is the deep fascia covering the muscle of the same 

 name. It is continuous with the pectoral in front, the infraspinous behind, and 

 the axillary below. 



The Deltoid Muscle. Detach this muscle from the clavicle (Fig. 131) and 

 acromion process of the scapula. Turn the muscle outward. Follow the muscle 

 to its insertion into the deltoid ridge, on the outer surface of the humenis. 

 (Fig. 127.) Cut this insertion and turn the muscle farther back, so as to expose 

 the insertion of the pectoralis major. 



The Pectoralis Major. Remove the fascia with a sharp scalpel. Place 

 the arm at a right angle to the body ; notice that the deep fascia you are now 



