[An anatomical study on lateral ligaments of rectum]

To identify the location and contents of the rectal lateral ligaments and its relationship with the middle rectal artery and pelvic plexus.

Twenty-nine pelvics of human cadavers were sagittally sectioned into 58 hemipelvic specimens. All of hemipelvics were dissected with sharp technique under direct vision by one surgeon. The lateral ligaments were identified and the distances from the center of its pelvic attachment to sacral promontory and coccyx were measured. Then, the lateral ligaments were transected for histologic examination.

Lateral ligaments of rectum were found in all 58 hemipelvics. The lateral ligaments connected the posterolateral aspect of the middle 1/3 of the rectum and mesorectum to the lateral aspect of the bodies of the second, third and fourth sacral vertebrae. The distance from the lateral ligament to sacral promontory was (8.3 +/- 1.6) cm on the right side and (8.4 +/- 1.4) cm on left side. The width of lateral ligaments was (3.2 +/- 0.4) cm on the right side and (3.1 +/- 0.4) cm on the left side. The distances from lateral ligament to the coccyx on the right and left sides were (5.2 +/- 1.4) cm and (5.0 +/- 1.3) cm respectively. The content of the lateral ligaments consisted of loose connective tissue with clusters of small nerves and blood vessels. Middle rectal artery was found in 83% (48/58) of hemipelvics and 47% (27/58) of the middle rectal artery went through the lateral ligaments. The inferior hypogastric nerve plexuses were formed inside the lateral ligament, and separated the ligament into two parts. The lateral segment of the lateral ligament contained the tributaries of internal iliac artery, and the medial segment contained nerve fibers or branches to the rectum, together with the middle rectal artery.

The lateral ligaments of rectum are located on the posterolateral side of the rectum, much closer to the coccyx than to the sacral promontory, consisting of connective tissue containing multiple small nerves and middle rectal artery. The lateral ligament is a pathway of blood vessels and nerve fibers toward the rectum and lymphatic vessels from the lower rectum toward the iliac lymph nodes.