Pectinate line
The pectinate line (dentate line) is a line which divides the upper two-thirds and lower third of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction.
It is an important anatomical landmark in humans, and forms the boundary between the anal canal and the rectum according to the anatomic definition. Colorectal surgeons instead define the anal canal as the zone from the anal verge to the anorectal ring (palpable structure formed by the external anal sphincter and the puborectalis muscle). Several distinctions can be made based upon the location of a structure relative to the pectinate line:
Additional images
Microscopic cross section of the anorectal junction
Anatomy of the anus and rectum
Coronal section of rectum and anal canal
