178 ELEMENTARY BIOLOGY. [CHAP. 



b. Carotid artery to the interior of the skull and 

 the brain. 



2. The system of the middle aortic arch (aortic trunks). 



a. Vertebral and subclavian to the vertebral co- 

 lumn, and to the fore-limb. (Esophageal to the 

 gullet. 



b. Cceliaco-mesenteric (given off from the left arch, 

 or from the dorsal aorta, at. or beyond, the junc- 

 tion of the two arches). 



a. Cceliac to stomach and liver. 



J3. Mesenteric to intestine and spleen. 



c. Branches of the dorsal aorta to the adrenal 

 and renal organs, to the genital organs and to 

 the muscles of the back. 



d. The terminal branches of the dorsal aorta (com- 

 mon iliac] ; each of these gives off hypogastric 

 arteries to the bladder and walls of the abdomen 

 and is continued as the femoral artery into the 

 leg. 



3. The system of the posterior aortic arch (pul mo- 



cutaneous trunk). 



a. Pulmonary artery to the lungs. 



b. Cutaneous artery to the dorsal integument. 



B. Veins. 



i. The system of the superior cava formed on each 

 side by the union of the vena innominata, the sub- 

 clavian and the external jugular. 



a. Internal jugular vein: leaves the skull by the 

 jugular foramen, and brings back blood from 



