194 



AORTA. 



intercostal muscles, towards the junction of the 

 rib with its cartilage, where it descends from 

 the rib towards the middle of the intercostal 

 space, and there anastomoses with the anterior 

 intercostal arteries sent off from the internal 

 mammary. Besides supplying the intercostal 

 muscles, pleura, and ribs, the intercostal arteries 

 give several branches, which pierce the external 

 layer of intercostal muscles, and carry blood 

 to the muscles and integuments covering the 

 thorax. The lower intercostalsalso send branches 

 to the abdominal muscles, diaphragm, and 

 quadratus lumborum, which freely anastomose 

 with the internal mammary, epigastric, phrenic, 

 lumbar, and circumflex iliac arteries. 



Anastomoses. The intercostal arteries have 

 a chain of anastomoses with each other by 

 communicating branches which cross the heads 

 of the ribs. By this means the superior freely 

 communicate with the subclavian by its inter- 

 costal artery. Inferiorly, their anastomosis 

 with the phrenic, circumflex ilii, and lumbar 

 arteries, is equally free; internally they anasto- 

 mose with the arteries of the spinal cord, and 

 in front with the internal mammary and epi- 

 gastric. 



III. Branches of the abdominal aorta. 

 They may be divided into anterior and lateral. 

 The anterior branches are, the inferior phrenic, 

 cctliac, superior and inferior mesenteric. 



Phrenic arteries. The phrenic arteries are 

 two in number; they arise from the aorta im- 

 mediately after its entrance into the abdomen, 

 generally distinct, sometimes from a common 

 trunk, and occasionally one or both arise from 

 the coeliac artery, or one of its branches. Each 

 phrenic artery passes outwards in front of the 

 crus of the diaphragm, and along the upper 

 edge of the renal capsule of its own side. The 

 right artery passes behind the vena cava, and 

 the left behind the oesophagus. They run on 

 the abdominal surface of the diaphragm, and 

 at the posterior edge of the cordiform tendon 

 each vessel divides into an external and an 

 anterior branch. The external branch supplies 

 tiie fleshy substance of the ala of the diaphragm, 

 and sends several branches towards the external 

 attachments of that muscle which anastomose 

 with the lower intercostal and lumbar arteries ; 

 while the anterior branch, coursing round the 

 margin of the cordiform tendon, supplies the 

 anterior part of the diaphragm, and anastomoses 

 with its fellow of the opposite side, behind the 

 ensiform cartilage, sending forwards branches 

 to anastomose with the internal mammary. 



Minute branches are given oft by the phrenic 

 arteries near their origins to the semilunar 

 ganglia and renal capsules : a small twig from 

 the right phrenic ascends along the vena cava 

 through the diaphragm to anastomose with the 

 comes nervi phrenici of the internal mammary. 

 Another similar twig, given to the oesophagus 

 by the left phrenic, while passing behind that 

 tube, anastomoses with the middle cesophageal 

 arteries. 



The ccdiac artery, called, also, caliac axis, 

 is one of the largest and shortest of the vessels 

 given off by the abdominal aorta. It generally 

 arises from the aorta, between the crura of the 



diaphragm opposite the junction of the last 

 dorsal and first abdominal vertebra, having the 

 renal capsules and semilunar ganglia on either 

 side of it, with the lobulus Spigelii to the right, 

 the cardiac orifice of the stomach to the left, 

 the superior border of the pancreas inferiorly, 

 and the stomach and lesser omentum in front : 

 it is closely embraced by branches of the solar 

 plexus. 



The coeliac artery, which is often scarcely 

 half an inch in length, immediately divides into 

 three branches, the gastric or coronaria superior 

 ventriculi, the hepatic, and the splenic, which 

 constitute the tripod of Haller. Sometimes the 

 cceliac axis gives off the phrenic and superior 

 capsular. 



Coronary artery of the stomach. The coro- 

 nary artery is the smallest of the three branches 

 furnished by the trunk of the caliac ; it some- 

 times arises from the aorta itself. Passing 

 upwards, forwards, and to the left, it arrives 

 at the cardiac orifice of the stomach, from 

 which it proceeds forwards and to the right, 

 following the direction of the lesser arch of 

 the stomach until it arrives near the pylorus, 

 where it anastomoses with the pyloric branch 

 of the hepatic. When the coronary artery has 

 arrived at the cardiac orifice of the stomach, it 

 sends one or more branches upwards along the 

 oesophagus which supply that part with blood, 

 and anastomose with the cesophageal arteries 

 from the thoracic aorta : it then sends branches 

 round the cardiac orifice, which nearly encircle 

 that part, and ramify over the great extremity of 

 the stomach, where they anastomose with the vasa 

 brevia of the splenic. In its course along the 

 lesser arch of the stomach the coronary sends 

 many branches over both surfaces of that viscus, 

 which anastomose with each other and with 

 the right and left gastro-epiploic. The ter- 

 minal branch of the coronary which ends at 

 the pylorus is sometimes called superior pyloric. 

 Sometimes the coronary artery gives off the 

 right hepatic immediately before reaching the 

 cardiac orifice of the stomach. 



The hepatic artery passes forwards and to 

 the right under the lobulus Spigelii to the neck 

 of the gall-bladder. In this part of its course 

 it gives a few twigs to the gastro-hepatic omen- 

 tum and the inferior surface of the liver ; when 

 it reaches the pylorus, it gives two considerable 

 branches called the pyloric and the right gastro- 

 epiploic. The pyloric passes from right to left 

 along the lesser arch of the stomach, where it 

 meets the coronary with which it anastomoses, 

 sending several branches over the anterior and 

 posterior surfaces of the stomach to anastomose 

 with the right gastro-epiploic artery. The right 

 gastro-epiploic artery, much larger than the 

 pyloric, arises after that vessel ; it passes down- 

 wards behind the pylorus, and arrives at the 

 greater arch of the stomach, along which it 

 courses from right to left and anastomoses 

 with the left gastro-epiploic. While passing 

 behind the pylorus, it gives several branches to 

 the pancreas and duodenum, one of which, 

 somewhat larger than the rest, called pancreatico- 

 duodenalis, lies concealed between the duo- 

 denum and head of the pancreas, and anasto- 



