Abdominal Aorta and Splachnic Vessels

Abstract

For vascular trauma purposes the abdomen is divided into four retroperitoneal anatomical areas: Zone 1: The midline retroperitoneum from the aortic hiatus to the sacral promontory is broken into supramesocolic and inframesocolic areas. The supramesocolic area contains the suprarenal aorta and its major branches (celiac artery, superior mesenteric artery, and renal arteries), the supramesocolic segment of the inferior vena cava with its major branches, and the superior mesenteric vein. The inframesocolic area contains the infrarenal aorta and infrarenal inferior vena cava. Zone 2 (left and right): This is the paired right and left region lateral of Zone 1 containing the kidneys and renal vessels. Zone 3: The pelvic retroperitoneum, which contains the iliac vessels. The abdominal aorta originates between the two crura of the diaphragm at the level of T12–L1 and bifurcates into the common iliac arteries at the level of L4–5. The umbilicus is an approximate external landmark for the aortic bifurcation. The first large branch is the celiac trunk, followed by the superior mesenteric artery 1–2 cm inferiorly, and both course anteriorly and inferiorly. The renal arteries originate 1–2 cm below the origin of the superior mesenteric artery at the level of L2 and course laterally. Finally, the inferior mesenteric artery originates 2–5 cm above the aortic bifurcation on the left anterior aspect of the aorta. Celiac artery: The main trunk originates on the anterior surface of the aorta at the level of T12–L1. It is 1–2 cm long and divides into three branches at the upper border of the pancreas—the common hepatic, left gastric, and splenic arteries. The celiac is encased in extensive fibrous, ganglionic, and lymphatic tissues, which makes surgical dissection of the celiac artery difficult. In 10–20% of patients, the left gastric artery gives off a replaced left hepatic artery that courses through the gastrohepatic omentum and can be injured while mobilizing the left lobe of the liver or lesser curve of the stomach. Superior mesenteric artery (SMA): The SMA originates from the anterior surface of the aorta at the level of L1, 1–2 cm below the celiac artery. It courses posterior to the neck of the pancreas and anterior to the third part of the duodenum, beyond which it enters the root of the mesentery. SMA branches include the inferior pancreaticoduodenal artery, the middle colic artery, an arterial arcade with 12–18 intestinal branches, the right colic artery, and the ileocolic artery. In 10–20% of patients, the SMA gives off a replaced right hepatic artery, which courses posterior to the head of the pancreas and runs posteriorly and to the right of the portal vein. Renal arteries: The right renal artery emerges at a slightly higher level and is longer than the left and courses posteriorly to the inferior vena cava. Approximately 30% of patients have more than one renal artery, usually an accessory artery supplying the lower pole of the kidney. Both renal veins lie anteriorly of their accompanying renal arteries. The left renal vein is significantly longer than the right and courses anteriorly to the aorta. The left renal vein drains the left gonadal vein inferiorly, the left adrenal vein superiorly, and the renolumbar vein posteriorly. The right gonadal vein drains directly into the IVC. Inferior mesenteric artery (IMA): The IMA provides blood supply to the left colon, sigmoid, and the rectum. It communicates with the SMA through the marginal artery of Drummond and arc of Riolan.