CIRCULATORY SYSTEM. 199 



other, d. Several long and short branches to the colox, which 

 furnish with lateral ramifications, distributed after the same 

 manner, the ccecal portion of the gut, and its two great flexures 

 or arches : the last of these branches, which is directed towards 

 the sigmoid flexure, is met in anastomosis by the first of the pos- 

 terior mesenteric 



3. The renal or e.mulgent arteries leave the aorta at 

 right angles, one on each side, directly opposite each other, either 

 about the same place as or somewhat posteriorly to the origin of 

 the preceding vessel. They pass directly outward in straight 

 lines, and each enters the notch of its appropriate kidney, and 

 therein splits into three or four large divisions which penetrate the 

 glandular substance. The right is the longer one, in consequence 

 of the inclination of the aorta to the left side, and its having to 

 cross the vena cava posterior in its course. Both furnish in their 

 way — a. Twigs to the enveloping adipose membrane, b. A small 

 artery destined for tlie supply of the capsula renalis : in some in- 

 stances this last vessel comes from the aorta ; rarely, from the 

 anterior mesenteric. 



4. The spermatic arteries, right and left, in comparison 

 to their diameter, are the longest vessels in the body, springing 

 near to each other from the under part of the aorta, about midway 

 between the origin of the renal arteries and its bifurcation : in some 

 instances these vessels come from the posterior mesenteric. They 

 pursue divergent and flexuous courses backward, pass out of the 

 abdomen at the internal abdominal rings, and enter into the con- 

 stitution of the chords with which they proceed to the testicles. 

 In the female, these arteries run within the layers of the broad 

 ligaments to the ovaries, to which they are principally distributed ; 

 but they also transmit branches to the Fallopian tubes and to the 

 horns of the uterus. 



5. The posterior or small mesenteric, the last of the 

 abdominal arteries, a much longer vessel than the anterior mesen- 

 teric, likewise comes from the under part of the aorta, and com- 

 monly very near to the roots of the spermatic arteries. It descends 

 within the folds of the mesocolon, and distributes its principal 

 branches to the left — to the sigmoid flexure of the colon ; the 

 others run backward and ramify upon the anterior portion of the 

 rectum : their arrangement and distribution are similar to the colic 

 ramifications of the anterior mesenteric. The anterior division 

 anastomoses with the posterior of the great mesenteric \ and the 

 posterior forms communications with the other arteries supplying 

 the rectum. 



6. Five or six pairs of lumbar arteries (according 

 with the number of vertebrae) are also furnished by the posterior 



