AXILLA. 103 



The AXILLARY ARTERY is that portion of the artery 

 destined to the upper extremity, intervening between the 

 subclavian and brachial arteries, and extending from the 

 outer border of the first rib to the lower margin of the 

 tendon of the latissimus dorsi and teres major; it passes 

 through the axilla nearer to its anterior than its posterior 

 border. The axillary vein lies in front and at the inside 

 of the artery, and is formed by the union of the basilic 

 vein of the arm and the venae comites of the brachial 

 artery ; it receives the cephalic vein near the clavicle, and 

 smaller veins, from the muscles, or which accompany the 

 branches of the axillary artery, enter it at various parts of 

 its course. 



The BRACHIAL PLEXUS, formed from the anterior 

 branches of the last four cervical, and the first dorsal 

 nerves (p. 59), lies upon the outer side of the axillary 

 artery at its upper part; lower down it surrounds the 

 rtery, giving off* its branches at various points. Some of 

 ;hese will be described with the dissection of the arm ; 

 those which are given to the thoracic and scapular mus- 

 cles will now be enumerated, though a further reference to 

 them will be made with the dissection of those muscles. 

 These nerves are six in number, viz: 





Superior Muscular, Supra-scapular, 



Short Thoracic, Sub-scapular, 



Long Thoracic, Inferior Muscular. 



The superior muscular supply the subclavius, rhomboidei, and 

 levator anguli scapulae muscles; they are branches of the fifth cer- 

 vical nerve, and are given off from the plexus behind the clavicle. 



The short thoracic, two in number, supply the pectoralis major and 

 minor muscles ; they are given off from the plexus at a point parallel 

 with the clavicle. 



The long thoracic passes down behind the axillary vessels and plexus, 

 ramifies on the side of the thorax, and is distributed to the fibres of 

 the serratus magnus muscle exclusively; it is a branch of the fourth 

 and fifth cervical nerves. 



The supra-scapular passing outward, goes through the supra-scapu- 

 lar notch, and supplies the supra- and iufra-spinatus muscles ; it is a 

 branch of the fifth cervical nerve. 



The sub-scapular are two in number, and are both distributed to the 

 sub-scapularis muscles; one of them comes from the plexus above the 

 clavicle, and the other from the posterior aspect of the plexus within 

 the axilla. 



The inferior muscular consist of one or more branches, distributed 

 to the teres major and latissimus dorsi muscles; they are given off 

 from the lower part of the plexus. 



