210 THE CAT. [chap. vii. 



and alar-thoracic arteries, wliich go respectively to the thoracic 

 muscles and axillarj'' lymphatic glands ; finally, the anterior and 

 posterior circumflex arteries (the latter being yery large) which pass 

 round and embrace the uppermost portion of the humerus. 



Below the axilla the axillary artery takes the name of hrachial, 

 and descends to the elbow between the biceps, the coraco-brachialis, 

 and the brachialis anticus muscles. It gives oflF a branch called the 

 superior profunda artery, which accompanies the muscular spiral 

 nerve and winds round the back of the humerus to its outer lower 

 part. Another branch, the inferior profunda artery, is given off 

 lower down, and passes to the inner side of the lower part of the 

 arm — in company with the ulnar nerve. Having passed through 

 the internal condyloid foramen and reached the concavity of the 

 elbow, the brachial artery divides into two branches, called the 

 radial and ulnar arteries. 



The ulnar artery (which is much smaller than the radial) passes 

 along on the ulnar side of the flexor surface of the fore-arm (beneath 

 the pronator teres, flexor carpi radialis, palmaris longus, and flexor 

 sublimis muscles) into the palm, when it joins a branch of the radial 

 artery to form a loop called the palmar arch. 



Soon after its origin the ulnar artery gives off a branch called 

 the interosseous artery, which descends along the anterior surface 

 of the interosseous membrane. 



The radial artery continues on the line of the brachial artery, 

 and extends along the flexor aspect of the radius to the wrist, when 

 it turns to the dorsal surface of the fore-paw and then penetrates 

 betM^een the second and thii'd metacarpal bones, and unites Math a 

 branch of the ulnar artery to form a palmar arch. The radial artery 

 is more superficial than the ulnar, being only overlapped by the 

 supinator longus muscle. The palmar arch gives off a very small 

 artery to the pollex and larger ones, which subdivide and go to the 

 four other digits. 



§ 19. The THORACK! AORTA passes backwards to the left and 

 ventral side of the vertebral column extending to the diaphragm, 

 after perforating which it becomes the abdominal aorta. It lies in 

 the posterior mediastinum (or dorsal space between the lungs) 

 beside the oesophagus. It gives off many small arteries, such as the 

 bronchial arteries (to nourish the lungs and the air- tubes), those of 

 the oesophagus and Intercostal arteries, which supply those intercostal 

 spaces which are not supplied by the intercostal branch of the sub- 

 clavian. Each intercostal artery passes along the posterior margin 

 of a rib on the deep surface of the external intercostal muscle. The 

 vessels of the right side have, of course, to cross transversely the 

 ventral surface of the vertebral column. Each intercostal also gives 

 off a small posterior or dorsal branch, which ascends, inside the ante- 

 rior costo-transverse ligament, to the muscles of the back. The two 

 hindmost intercostals on each side are rather lumbar than dorsal 

 arteries, since they traverse the trunk behind the last rib. 



The AUDOMiNAL -AORTA is thc Continuation backwards, beyond the 



