228 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



of them. It passes laterally. It gives off a conspicuous cutaneous artery which 

 lies on the inner surface of the pectoral girdle. It branches to nearby muscles 

 and the skin. The subclavian then gives off an artery to the shoulder and as 

 the brachial artery passes into the fore limb where it branches extensively. 



In its course along the pleuroperitoneal cavity the dorsal aorta gives off both 

 visceral and somatic branches. The median visceral branches will be described 

 first. 



The first visceral branch of the dorsal aorta is the gastric artery. It passes 

 to the stomach and forks into the dorsal and ventral gastric arteries supplying the 

 corresponding walls of the stomach. The ventral gastric artery also furnishes 

 a few small branches to the spleen. Some distance posterior to the origin of 

 the gastric artery, the coeliaco-mesenteric artery springs from the aorta. It 

 passes ventrally in the mesentery giving rise to some mesenteric branches to the 

 beginning of the small intestine; it then proceeds to the region of the hepato- 

 duodenal ligament where it branches into a splenic artery to the spleen, a 

 pancreatico-duodenal artery to the pancreas, duodenum and pyloric region of 

 the stomach, and a hepatic artery, which runs along the dorsal surface of the 

 liver in contact with the hepatic portal vein and supplies numerous branches 

 to the liver substance. Posterior to the point of origin of the coeliaco- 

 mesenteric vessel, the dorsal aorta gives off a number of mesenteric arteries into 

 the intestine. 



The lateral visceral branches of the dorsal aorta consist of numerous genital 

 arteries to the testes in the male, and ovaries and oviducts in the female, and of 

 renal arteries to the kidneys. The somatic branches of the aorta consist of the 

 parietal or intercostal arteries. These arise from the dorsal side of the aorta at 

 segmental intervals; they pass dorsally and divide in two, one branch going to 

 each side of the body. These branches pass laterally along the internal surface 

 of the body wall and supply the body musculature. 



Near the posterior end of the pleuroperitoneal cavity, the aorta gives off 

 on each side an iliac artery, which passes laterally alongside the femoral vein 

 toward the hind limb. It gives off an epigastric artery which runs anteriorly 

 along the body wall, a hypo gastric branch to the urinary bladder and cloaca, and 

 as the femoral enters the hind limb, into which it should be traced. It runs 

 along the medial side of the leg and at the knee gives rise to a number of branches. 

 The dorsal aorta proceeds into the tail as the caudal artery, giving off a pair of 

 cloacal arteries into the cloaca as it passes that region. 



Draw the branches of the dorsal aorta. 



8. The chambers of the heart. Remove the heart from the pericardial 

 cavity by cutting across both ends. The chambers of heart were previously 

 named. The sinus venosus is a chamber with very thin, delicate walls. It 

 receives from behind the two large trunks formed by the union of the common 

 cardinal vein and hepatic sinus on each side. Anteriorly tJ^e sinus passes into 



