298 BRANCHES OP THE ABDOMINAL AORTA. 



the borders of the contiguous ribs between the two planes of inter- 

 costal muscles, and anastomose with the anterior intercostal arteries, 

 branches of the internal mammary. The branch corresponding 

 with the lower border of each rib is the larger of the two. They 

 are protected from pressure during the action of the intercostal 

 muscles, by little tendinous arches thrown across and attached by 

 each extremity to the bone. 



BRANCHES OF THE ABDOMINAL AORTA. 



Phrenic, 



C Gastric, 

 Cceliac axis < Hepatic, 



( Splenic, 



Superior mesenteric, 

 Spermatic, 

 Inferior mesenteric, 

 Supra-renal, or capsular, 

 Renal, or emulgent, 

 Lumbar, 

 f Sacra media. 



The PHRENIC ARTERIES are given off from the anterior part of the 

 aorta as soon as that trunk has passed through the aortic opening. 

 Passing obliquely outwards upon the under surface of the diaphragm, 

 each artery divides into two branches, an internal branch which 

 runs forwards and inosculates with its fellow of the opposite side in 

 front of the cesophageal opening ; and an external branch which 

 proceeds outwards towards the great circumference of the muscle, 

 and sends branches to the supra-renal capsules. The phrenic arte- 

 ries inosculate with branches of the internal mammary, inferior 

 intercostal, epigastric, cesophageal, gastric, hepatic, and supra-renal 

 arteries. They are frequently derived from the cceliac axis, or 

 from one of its divisions, and sometimes they give off the supra- 

 renal arteries. 



The COSLIAC Axis (xoiXi'a ventriculus) is the first single trunk given 

 off from the abdominal aorta. It arises opposite the upper border 

 of the first lumbar vertebrae, is about half an inch in length, and 

 divides into three large branches gastric, hepatic, and splenic. 



Relations. The trunk of the ccEliac axis has in relation with it, 

 in front the lesser omentum ; on the right side the right semilunar 

 ganglion and lobulus Spigelii of the liver ; on the left side the left 

 semilunar ganglion and cardiac portion of the stomach ; and below 

 the upper border of the pancreas and lesser curve of the stomach. 

 It is completely surrounded by the solar plexus. 



The GASTRIC ARTERY (coronaria ventriculi), the smallest of the 

 three branches of the cceliac axis, ascends between the two layers 

 of the lesser omentum to the cardiac orifice of the stomach, then 

 runs along the lesser curvature to the pylorus, and inosculates with 

 the pyloric branch of the hepatic. It is distributed to the lower 



