Perineum LO6

6. Understand the location of the pectinate line, and the structural and neurovascular differences of the regions superior and inferior to the pectinate line.

The pectinate (dentate) line demarcates the proximal two-thirds from the distal one-third of the anal canal. The pectinate line is useful to distinguish regions of the anal canal that vary with respect to: embryological origin, neurovascular service, lymphatic drainage, type of epithelial tissue, and classification of hemorrhoid (see table below).