The right and left colon mesenteries were fused with the posterior parietal peritoneum on either side during embryonic life. The lateral attachments of these fusion fasciae lie at the lateral borders of the colon. Lifting up on the colon folds the adjacent edge of peritoneum up into the "white line" of Toldt and marks the beginning of the plane to mobilize the colon. The inferior mesenteric artery (see lower GI bleed) supplies the left colon and rectum, and its branches lie along the left posterior abdominal wall. The transverse colon is mobile on its mesentery, and drapes downward in the upright position. The redundancy and mobility of the sigmoid is variable. The transverse mesocolon crosses the pancreas and second portion of the duodenum. The splenic flexure of the colon is held up by attachments to the margin of the diaphragm (phrenocolic ligament/sustentaculum lieni) and splenocolic ligaments. division of the latter must be done carefully to avoid tearing the splenic capsule.
The greater curve of the stomach (see stomach rotation) lies within the gastric impression of the spleen, and then parallels the sweep of the transverse colon. The greater omentum has a short segment between stomach and colon (gastrocolic omentum) before draping over the small bowel. The gastroepiploic arcade lies within this membrane. The short gastric vessels between splenic hilum and greater curve of the stomach are longest at the lower pole of the spleen, and shortest at the upper pole, making division of the highest short gastrics more hazardous.
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