THE ARTERIES. — 283 
3. A. subclavia sinistra (Fig. 115, &; Fig. 118, c).—The 
left subclavian passes craniad from the convexity of the aortic 
arch. It curves about the first rib (Fig. 118, 7) to enter the 
armpit, where it becomes the axillary artery (7). 
4. Aa. intercostales ().—The intercostal arteries are given 
off from the dorsal side of the aorta. Each passes to an inter- 
costal space and divides into three. branches. One of these 
passes ventrad along the caudal margin of the cranial one of 
the two ribs between which it extends. Another goes to 
the deep muscles of the back, and the third enters the spinal 
canal through the intervertebral foramen. The arteries for the 
first and’second (and sometimes the third) intercostal space 
usually arise from the subclavian (costocervical axis, Fig. 
118, g). 
5. Aa. bronchiales.—The bronchial arteries are two, and 
arise either from the aorta opposite the fourth intercostal space 
or from the fourth intercostal arteries. They accompany the 
bronchi to the lungs. 
6. Aa. esophagee (Fig. 118, 0).—The cesophageal arteries 
are small branches of varying origin passing to the cesophagus. 
7. Aa. lumbales.—The lumbar arteries correspond to the 
intercostals, but pass off between the lumbar vertebrae. The 
obliquity of the diaphragm throws the origin of one or two 
pairs of them within the thorax. 
A. CAROTIS COMMUNIS. THE COMMON CAROTID ARTERY. 
(Fig. 115, Zand m; Fig. 119, a). 
The two common carotid arteries arise from the innom- 
inate artery in the manner already described. Each 
passes craniad along the side of the trachea. In the thorax 
(Fig. 118, f) the common carotid lies mediad of the sub- 
clavian artery (Fig. 118, ¢) and dorsad of the superior vena 
cava (Fig. 118, g). In the neck (Fig. 119) the artery lies, 
accompanied by the vagus and sympathetic nerves and the 
internal jugular vein (4), in the space between the longus 
capitis muscle (7) and the trachea (14); it is covered ventrally 
by the sternomastoid and sternothyroid (2) muscles, lying close 
to the lateral border of the latter. Near its origin the common 
carotid may give rise to the small inferior thyroid artery. It 
