Intermediate lateral flexure of rectum

The intermediate (middle) lateral flexure of rectum is the most prominent and constant of the three lateral curvatures of the rectum. It is located in the middle part of the rectum, approximately 6-8 cm above the anal verge, and corresponds to the level of the middle transverse rectal fold (Kohlrausch's fold). The flexure is typically convex to the left, while the associated middle transverse rectal fold projects into the lumen from the right lateral wall.

The intermediate lateral flexure contributes to the zigzag course of the rectal lumen and is associated with the largest and most constant of the transverse rectal folds. The middle transverse rectal fold is formed by the mucosa, submucosa, and a thickening of the circular muscle layer. Together, the flexure and fold help support the weight of accumulated faecal material, reduce its direct descent into the anal canal, and thereby contribute to faecal continence and the temporary storage function of the rectum.

Clinical correlate

Because the intermediate lateral flexure and the middle transverse rectal fold are the most constant rectal flexures and folds, they serves as a valuable reference points in endoscopic and surgical procedures.