126 Anatomy of the Rabbit. 



(8) Terminal branches to the parts, about the sacculus 

 rotundus; anastomosing with (4). 

 (d) The intestinal arteries (aa. intestinales), about twenty in 

 number, are given off from the superior mesenteric artery, 

 and are distributed to the free portion of the mesenterial 

 small intestine. The successive vessels are connected by 

 anastomoses. The end of the superior mesenteric artery has 

 the relation of one of the intestinal arteries. It anastomoses 

 forwards with a single branch given off from the side of the 

 vessel opposite to the intestinal arteries, and the latter in 

 turn anastomoses forwards with a branch of the appendicular 

 artery. 



8. Locate in the descending mesocolon the inferior mesenteric artery 

 (a. mesenterica inferior), a small median vessel arising from the abdominal 

 aorta. It has two main branches — the left colic artery (a. colica sinistra) 

 to the anterior portion of the descending colon (anastomosing with the 

 middle colic), and the superior haemorrhoidal artery (a. haemorrhoidalis 

 superior) to the posterior portion of the colon and the rectum. 



9. The superior mesenteric vein (v. mesenterica superior), the chief 

 tributary of the portal, collects the blood distributed by the superior 

 mesenteric artery, its tributaries being similar in arrangement to the 

 branches of the artery. The inferior mesenteric vein (v. mesenterica 

 inferior) collects blood from the descending colon and rectum; it may 

 be traced forward in the descending mesocolon. 



10. Sympathetic plexuses. In the descending mesocolon will be 

 found the inferior mesenteric ganglion (g. mesentericum inferius), a 

 narrow curved body situated in front of the inferior mesenteric artery. 

 Surrounding the abdominal aorta and appearing in the mesocolon is the 

 abdominal aortic plexus (plexus aorticus abdominalis). It is connected 

 anteriorly with the coeliac and superior mesenteric plexuses (p. 118) 

 accompanying the corresponding vessels, and with the renal plexuses 

 accompanying the renal vessels to the kidneys; posteriorly with the 

 inferior mesenteric and spermatic plexuses about the inferior mesenteric 

 and internal spermatic arteries, and with the hypogastric plexus about 

 the pelvic vessels. 



11. By dividing the rectum close in front of the pelvis, and severing 

 the peritoneal attachments, the intestines may be separated and laid out 

 in an extended condition. The relations to one another of the ileum, 

 caecum, and colon are studied to much better advantage than in the 

 natural position. 



