The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm.

In humans, the anal canal is approximately 2.5 to 4 cm (0.98 to 1.57 in) long, from the anorectal junction to the anus.

It is surrounded by inner involuntary and outer voluntary sphincters which keep the lumen closed in the form of an anteroposterior slit.

The canal is differentiated from the rectum by a transition along the internal surface from endodermal to skin-like ectodermal tissue.

The anal gland secretes lymphal discharge and built-up fecal matter from the colon lining.