218 The Alligator and Its Allies 



of the shoulder; (b) the thoracic, t 1 , carrying blood 

 to the posterior muscles of the shoulder and to the 

 posterior region of the upper arm; (c) the brachial, 

 br 1 , which is really the continuation of the subclav- 

 ian and is the chief artery of the anterior appendage. 



After sending several branches to the upper arm 

 the brachial divides, in the region of the elbow, 

 into two main vessels, the radial, ra 1 , and ulnar, 

 ul 1 , arteries, Fig. 62, A. The radial artery, in the 

 carpal region, divides in a complicated way into 

 five main vessels that extend into the digits. 

 The ulnar artery gives off several branches to the 

 forearm, but apparently does not connect directly 

 with the branches to the digits. 



The primary carotid, capr. After leaving the 

 heart, this very large vessel passes cephalad and 

 laterad for some distance on the left side of the 

 body and then gives off, from its anterior side, the 

 large left subclavian artery, sc.s., to be described 

 later. After giving off the subclavian artery, it 

 makes a short loop, still farther to the left, and then 

 turns sharply mediad to pass to the head in the 

 median plane directly dorsal to the oesophagus. 

 Its distribution in the cervical and cephalic region 

 will be described later. The mate to the cesoph- 

 ageal branch, oe (near heart), of the right sub- 

 clavian which was mentioned above is apparently 

 sometimes given off from the primary carotid near 

 its base (as shown in Fig. 62) and sometimes as a 

 branch of the left pleural artery. 



