278 A MANUAL OF ANATOMY. 



along the upper border of the pectoralis minor. (&) The 

 acromiothoracic. This arises as a short trunk from the 

 front of the axillary, j ust above the pectoralis minor, pierces 

 the costocoracoid membrane, and breaks up into three or 

 four sets of branches ; the humeral (descending), which 

 accompanies the cephalic vein into the groove between the 

 deltoid and pectoralis major muscles ; the acromial, usu- 

 ally a branch from the above, to the region of the point of 

 the shoulder ; the thoracic, two or three branches to the 

 chest and pectoral muscles ; the clavicular, often from 

 the thoracic to the subclavius muscle. 



Second Portion. (a) The alar thoracic. There may be 

 one or several alar arteries, and they may arise from the 

 axillary or from the neighboring branches, usually from the 

 long thoracic. They supply the glandular and adipose 

 tissue in the axillary space. (b~) The long- thoracic is 

 given off from the inner side of the axillary behind the 

 pectoralis minor, passes along the lower border of the same, 

 and is distributed to the pectoral muscles, side of chest, 

 and mammary gland. 



Third Portion. (a) The subscapular, the largest branch 

 of the axillary artery, arises from its inner side just above 

 the lower border of the subscapularis muscle, passes down- 

 ward and inward to the chest, lying in the angle between 

 the subscapularis, teres major, and latissimus dorsi muscles, 

 and terminating in the serratus magnus muscle. About one 

 inch from its origin the artery gives off the dorsal artery of 

 the scapula (dorsalis scapidce), a large branch (really the 

 continuation of the subscapular) which winds backward 

 around the axillary (outer) border of the scapula to its 

 posterior surface. It passes through the triangle formed by 

 the subscapularis, teres major, and long head of the triceps 

 muscles. For rest of course see page 371. (b) The anterior 



