The vascular and neuronal composition of the lateral ligament of the rectum and the rectosacral fascia.

Detailed dissections were performed on 83 pelvic halves from 45 cadavers in order to obtain more accurate data on the composition of the lateral ligament of the rectum and the rectosacral fascia. The middle rectal artery was observed in only 18 out of 81 spcimens (22.2%). The lateral ligament of the rectum was divided into lateral and medial portions, according to the positional relationship to the pelvic plexus. The lateral part consisted of a superoanterior and an inferoposterior subdivision. The main component of the former was the middle rectal artery, while the pelvic splanchnic nerves were contained in the latter. Both compoents can be considered to contribute to the formation of the medial part, although the middle rectal vessels were not always present. The medial part consisted of the rectal branches from the pelvic plexus and their connective tissue. The rectosacral fascia was formed by dense connective tissue between the posterior wall of the rectum and the third and fourth sacral vertebrae. The main components of the fascia were branches of the lateral and median sacral vessels and the sacral splanchnic nerves which arose directly from the sacral sympathetic ganglia.