THE THORACIC AORTA. 247 



THE THORACIC AORTA. 



Begins at the left side of the lower border of the 

 fourth dorsal vertebra ; at the aortic opening it becomes 

 the abdominal aorta. The thoracic aorta sends off the 

 pericardiac, bronchial, posterior mediastinal, and cesopha- 

 geal and ten pairs of intercostals to the lower intercostal 

 spaces. 



THE ABDOMINAL AORTA. 



Commences at the aortic opening of diaphragm and 

 divides at the lower border of the fourth lumbar vertebra 

 into the common iliacs. It sends off: 



Phrenic. Two or three branches to under surface 

 of diaphragm. 



Cceliac Axis. The cceliac axis divides into three 

 branches: 1. Gastric, runs along the lesser curvature 

 of the stomach from cardiac end to pylorus. It anas- 

 tomoses with the pyloric branch of the hepatic and 

 distributes branches to both sides of the stomach. 

 2. Hepatic, passes to the liver; it gives off the pyloric, 

 gastro-duodenalis, which divides into the pancreatico- 

 duodenal and the gastro-epiploica dextra, and the 

 cystic to gall-bladder. The former anastomoses with 

 the pancreatico-duodenal of the superior mesenteric, 

 and the latter with the gastro-epiploica siriistra of the 

 splenic, forming the anastomoses around the greater 

 curvature of the stomach. 3. Splenic, sends off branches 

 to pancreas and the gastro-epiploica sinistra. 



Superior Mesenteric. Supplies small intestine and 

 ascending and transverse colon. It sends off five 

 branches : 1. Inferior pancreatico-duodenal, anastomosing 

 with the vessel of same name from gastro-duodenalis. 

 2. Colica media, sending branches to the transverse and 

 ascending colon ; it anastomoses on the right with the 

 colica dextra, on the left with ascending branch of the 



