294 THE CIRCULATORY SYSTEM. 
é. A. axillaris (Fig. 122, g).—The axillary artery is the 
continuation of the subclavian laterad of the first rib. It lies 
caudad of the brachial plexus and parallel to it. It sends off 
the following branches: 
1. A. thoracica anterior (Fig. 122, %).—The anterior 
thoracic is a slender artery which leaves the ventral side of the 
axillary opposite the first rib and passes caudomediad, to supply 
the medial ends of the pectoral muscles (g). 
2. A. thoracica longa (/).—The long thoracic artery is 
larger than the preceding, leaves the axillary a short distance 
laterad of it, and passes caudad to the middle portions of the 
pectoral muscles (8) and continues to the inner surface of the 
latissimus dorsi. 
A short distance beyond the long thoracic the axillary 
divides into two. The more cranial one of these is the sub- 
scapular (/); the other is the brachial (g’). 
3. A. subscapularis (/).—The subscapular artery passes 
laterad and gives off a short distance from its origin the 
A. thoracicodorsalis (2) and A. circumflexa humeri posterior 
(see below); it may also give rise to the circumflexa anterior 
humeri (/’), and to the profunda brachii (w); these two 
branches, however, rise more frequently from the brachial 
artery (g’) and are described in connection with it. The sub- 
scapular artery then passes through the triangular interval 
between the scapular end of the long head of the triceps, the 
latissimus dorsi, and the glenoid border of the scapula. Within 
this interval it sends muscular branches to the long head of the 
triceps, the subscapularis, and the latissimus dorsi. That to 
the latter muscle is very large. At the border of the scapula, 
opposite the tuberosity of the spine, it turns craniad, passes 
over the Jateral surface of the infraspinatus muscle, supplying 
it; crosses the spine, and sends branches into the supraspinatus 
fossa in both directions parallel to the scapular spine. These 
supply the supraspinatus, acromiotrapezius, and spinotrapezius, 
and anastomose with the branches of the transversa scapule. 
As the subscapularis turns craniad onto the surface of the infra- 
spinatus it sends dorsad a small branch, the circumflexa 
scapule, which passes in the infraspinatus fossa close to its 
