jejunum, ileum: intestinal aa. are 12-15 in number and are found in the mesentery: marginal: formed by anastomoses of branches of the ileocolic a., right colic a., middle colic a., left colic a., sigmoid a. colic brs. colon: an important anastomosis for the large intestine: mesenteric, inferior: abdominal aorta at the level of the L3 vertebral body