The mesorectal fascia is a layer of connective tissue enclosing the peri-rectal fat that surrounds the rectum.
It is not an anatomical termed recognized by the Terminologia Anatomica because it is mainly a surgical and radiological term for rectal cancer staging.
The mesorectal fascia envelopes the mesorectum, the perirectal fat which surrounds the rectum within the pelvis that contains the superior rectal artery and branches, superior rectal vein and tributaries, and lymph nodes and vessels
It extends from the beginning of the rectum to levator ani. The mesorectal fascia begins at the rectosigmoid junction where it blends with the connective tissue of the sigmoid mesentery. It extends to the end of the rectum at levator ani. Laterally it extends around the rectum and peri-rectal fat and becomes contiguous anteriorly with the rectovesical fascia (Denonvilliers' fascia). Posteriorly it fuses with the presacral fascia (Waldeyer's fascia).