62 LABORATORY DIRECTIONS 



6. Internal Mammary Artery. — This arises on the ven- 

 tral side of the subclavian at about the same level as the verte- 

 bral and runs caudally on the Inner surface of the sternum. It 

 is best seen when removing the thoracic body wall. 



7. Axillary Artery. — Several other branches are given 

 off from the subclavian before it leaves the thoracic cavity and 

 becomes the axillary artery. The axillary supplies the arm and 

 muscles of the shoulder. Trace the main branches. 



8. Internal and External Carotid Arteries. — Follow 

 the common carotid and observe that It passes to the head, giving 

 off small branches on the way. It eventually gives rise to the 

 internal carotid, which passes to the tympanic bulla and enters 

 the skull, and the external carotid, which divides into several 

 smaller branches supplying the lips, floor of the mouth, tongue 

 and portions of the face. 



Turn again to the aorta and follow it posteriorly. 



9. Intercostal Arteries. — There are about ten pairs of 

 these that leave the aorta after it reaches the dorsal side. They 

 supply the muscles of the back, Intercostal spaces, and the 

 spinal cord. 



10. Lumbar Arteries. — These correspond to the inter- 

 costals in the lumbar region. There are several pairs of them. 

 The first two pairs originate In the thorax. 



11. CoELiAC Artery. — This Is a single large branch from 

 the abdominal aorta arising near the point where the aorta 

 penetrates the diaphragm. It divides Into three branches. 



a. The hepatic artery, arises nearest to the origin of the 

 coeliac and passes directly to the liver. Near the pylorus it 

 sends a branch to the stomach and Intestines. 



b. The gastric leads to the stomach. 



c. The splenic, the largest of the three branches, divides and 

 supplies the spleen and pancreas. 



12. Superior Mesenteric Artery.— This arises from the 

 aorta just caudal to the coeliac and may be larger than the 

 coeliac. It sends branches to the small Intestine, pancreas, and 

 parts of the colon. The branches follow the mesenteries and 

 are paralleled by veins. 



13. Adrenolumbar Artery. — ^Arising from the aorta, one 

 on either side about two centimeters caudal to the superior 

 mesenteric, each supplies the muscles of the dorsal body wall. 



