AXILLARY ARTERY. 289 



inner or thoracic side it is in relation, first, with the first intercostal 

 muscle ; . it next rests upon the first serration of the serratus magnus ; 

 and is then separated from the chest by the brachial plexus of nerves. 

 By its outer or humeral side it is at first separated from the brachial 

 plexus by a triangular cellular interval ; it next rests against the 

 tendon of the subscapularis muscle ; and thirdly upon the coraco-bra- 

 chialis muscle. 



The relations of the axillary artery may be thus arranged : 

 In front. Inner or thoracic Side. Outer or humeral Side. 



Pectoralis major, First intercostal muscle, Plexus of nerves, 

 Pectoralis minor, First serration of ser- Tendon of sub- 

 Pectoralis major. ratus magnus, scapularis, 



Plexus of nerves. Coraco-brachialis. 



Branches. The branches of the Axillary artery are seven in 

 number : 



Thoracica acromialis, 

 Superior thoracic, 

 Inferior thoracic, 

 Thoracica axillaris, 

 Subscapular, 

 Circumflex anterior, 

 Circumflex posterior. 



The thoracica acromialis and superior thoracic are found in the 

 triangular space above the pectoralis minor. 



The inferior thoracic and thoracica axillaris, below the pecto- 

 ralis minor. 



And the three remaining branches below the lower border of the 

 subscapularis. 



The Thoracica acromialis is a short trunk which ascends to the 

 space above the pectoralis minor muscle, and divides into three 

 branches, thoracic, which is distributed to the pectoral muscles 

 and mammary gland; acromial, which passes outwards to the 

 acromion, and inosculates with branches of the supra-scapular 

 artery ; and descending, which follows the interspace between the 

 deltoid and pectoralis major muscles, and is in relation with the 

 cephalic vein. 



The Superior thoracic (short), very frequently arises by a common 

 trunk with the preceding ; it runs along the upper border of the 

 pectoralis minor, and is distributed to the pectoral muscles and 

 mammary gland, inosculating with the intercostal and mammary 

 arteries. 



The Inferior thoracic (long external mammary) descends along 

 the lower border of the pectoralis minor to the side of the chest. It 

 is distributed to the pectoralis major and minor, serratus magnus, 

 and subscapularis muscle, to the axillary glands and mammary 

 gland ; inosculating with the superior thoracic, intercostal, and 

 mammary arteries. 



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