Editing Retroperitoneum (section)

== Arterial Vasculature ==

* '''Arterial structures have 3 layers (innermost to outermost):'''
** '''Tunica intima (intima)'''
** '''Tunica media (media)'''
** '''Tunica externa (tunica adventitia or adventitia)'''
* '''Abdominal aorta'''
** See CW11 Table 33-3 for Branches of the Abdominal Aorta
** '''Branches from superior to inferior'''
**# '''Inferior phrenic arteries (paired)'''
**#* Supply inferior surface of the diaphragm
**#* '''The superior adrenal arteries branch off the inferior phrenic arteries to supply the ipsilateral adrenal gland'''
**# '''Celiac artery'''
**#* '''Branches (3):'''
**#*# '''Gastric'''
**#*# '''Splenic'''
**#*# '''Common hepatic'''
**#** '''The splenic vessels course on the cephalad aspect of the body and tail of the pancreas'''
**#** '''Right gastric arises from common hepatic arteries'''
**#* Supplies the abdominal esophagus, stomach, duodenum, spleen, liver, and pancreas
**# '''Middle adrenal (suprarenal) arteries (paired)'''
**#* Supply the ipsilateral adrenal gland
**#* [May be above or at level of SMA]
**# '''Superior mesenteric artery'''
**#* Arises anteriorly in the midline at approximately the level of the middle adrenal arteries at L1-L2
**#* Supplies the pancreas, small intestine, and most of the large intestine
**#* '''Branches (4)'''
**#*# '''Inferior pancreaticoduodenal'''
**#*# '''Ileocolic'''
**#*# '''Right colic'''
**#*# '''Middle colic'''
**#** '''The middle colic artery anastomoses with the left colic artery off the inferior mesenteric artery (IMA) via the marginal artery of Drummond. This anastomosis forms an important SMA-to-IMA collateral circulation that allows for the IMA to be sacrificed without colonic ischemia. However, despite the presence of this collateral circulation, injury to the SMA during left-sided retroperitoneal surgery may lead to severe bowel ischemia.'''
**# '''Renal arteries (paired)'''
**#* At L1 vertebral level
**#* '''The inferior adrenal arteries branch off the renal arteries to supply the ipsilateral adrenal gland'''
**# '''Gonadal arteries (paired)'''
**#* '''Called testicular arteries in males and ovarian arteries in females.'''
**#** '''The testicular arteries typically run anterior to the psoas, IVC, genitofemoral nerve, and ipsilateral ureter as they travel toward the internal inguinal ring.'''
**#** '''The ovarian arteries travel anterior to the ureter and course medially as they pass through the infundibulopelvic ligament (suspensory ligament of the ovary) to the ovary'''
**#* There are extensive collaterals to the gonads in both sexes, allowing for ligation of the testicular and ovarian arteries without gonadal ischemia.
**# '''Lumbar arteries (paired)'''
**#* '''4 paired arteries'''
**#* Arise posteriorly, adjacent to the bodies of the upper 4 lumbar vertebrae
**#* Supply the posterior body wall and spine
**# '''Inferior mesenteric artery (IMA)'''
**#* Arises from the anterior aorta
**#* '''Supplies the colon from the splenic flexure to the upper rectum'''
**#* '''Branches (3)'''
**#*# '''Left colic'''
**#*# '''Sigmoid'''
**#*# '''Superior rectal (hemorrhoidal)'''
**#** The sigmoid artery branches into 2-3 inferior left colic arteries.
**#** '''The superior rectal artery has anastomoses with (2)'''
**#**# '''Middle rectal artery (arises from anterior branch of internal iliac).'''
**#**# '''Inferior rectal artery (arises from internal pudendal, which arises from anterior branch of internal iliac)'''.
**#*** '''These collaterals for an important internal iliac-to-IMA that provides blood supply to the rectum and prevent ischemia during IMA ligation.'''
**# '''Middle sacral artery'''
**#* Arises from the posterior aspect of the aorta before bifurcation.
**# No named branches are given off as these arteries enter the pelvis and divide to form the internal and external iliac arteries.