THE ARTERIES 



745 



(1) The vertebral artery arises opposite the first intercostal space from the 

 dorsal face of the parent trunk. It runs forward on the longus colli (crossing the 

 trachea on the right side), and passes along the neck in typical fashion to the third 

 cervical vertebra, where it divides into three branches. The largest of these supplies 

 the muscles in this region, compensating for the absence of branches of the deep 

 cervical artery. The second passes between the second and third cervical vertebra 

 into the vertebral canal and unites with the opposite artery and a branch of the 

 occipital artery to form the basilar artery. The third branch is the small continua- 



Fig. 614. — Vessels, Nerves, Etc., of Thorax of Dog; Left View. 

 1, First rib (stump) : 3, sternum; 2', manubrium sterni; 2", xiphoid cartilage; 3, trachea; 3', bifurcation of trachea; 

 4, cesophagus; 5—8, ventral branches of fifth to eighth cervical nerves; 9, ventral branch of first thoracic nerve; 10, 10', 

 muscular and tendinous parts of diaphragm; 11, 11', left ventricle and auricle of heart; 12, 12' , right ventricle and auricle 

 of heart; 13, 13', left coronary artery (descending branch) and great cardiac vein; 14, branch of left coronary artery in 

 intermediate groove; ./5, pulmonary artery; i5, pulmonary veins; 77, ./S, aorta; 75, anterior vena cava; 20, 20', 20", 

 intercostal nerve, artery, and vein; 21, thoracic duct; 22, 22' , internal thoracic vessels; 23, sternal branches of 22; 24, 

 mediastinal arteries; £5, musculo-phrenic artery; 26, anterior abdominal artery; 27, inferior cervical (or omo-cervical) 

 artery; 28, brachial vessels; 29, external thoracic artery; 30, left common jugular vein; 31, m. longus colli; 32, an- 

 terior mediastinal lymph glands; S3, sternal lymph glands; a, brachiocephalic artery; b, b', common carotid arteries; 

 c, c', brachial arteries; d, left brachial vein; e, e', dorso-cer\'ical vessels; /, /', vertebral vessels; g, dorsal vessels; h, 

 subcostal vessels; i, deep cervical vessels; k, recurrent nerve; I, vago-sympathetic trunk; V, I", dorsal and ventral 

 branches of vagus; m, phrenic nerve; n, roots of phrenic nerve from fifth to seventh cervical nerves; o, thoracic trunk 

 of sympathetic; o', ansa subclavia formed by branches connecting posterior cer\'ical and first thoracic ganglia; o", 

 great splanchnic nerve; p, thoracic ganglia of sympathetic; q, rami communicantes; r, posterior cervical ganglion; s, 

 first thoracic ganglion of sympathetic; t, v, v, rami communicantes connecting s with seventh and eighth cervical and 

 first thoracic nerves; w, cardiac branch of first thoracic nerve; x, cardiac nerves from posterior cervical ganglion; y, 

 bronchial branches of vagus; z, depressor nerve. (After Bucher.) 



tion of the parent trunk; it passes to the wing of the atlas and anastomoses with 

 the occipital artery. 



(2), (3) The dorsal and deep cervical arteries arise by a common trunk close 

 to the vertebral. The trunk crosses the lateral face of the latter, ascends on the 

 longus colh, and divides into two branches. The anterior branch, the deep cervical 

 artery, emerges medial to the upper end of the first rib and ramifies in the deep 

 muscles of the neck. The dorsal artery gives off the subcostal artery (which 

 supplies two or three intercostal arteries) and emerges through the dorsal end of 

 the first intercostal space and ramifies in the spinal muscles. 



