pectinate line 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. not to be confused with pectineal line (pubis). pectinate linepectinate line labeled at bottom center.the interior of the anal cami and lower part of the rectum, showing the columns of morgagni and the anal valves between their lower ends. (pectinate line visible but not labeled.)detailsidentifierslatinlinea pectinata, linea anocutaneata98a05.7.05.009ta23015fma29321anatomical terminology it is an important anatomical landmark in humans, and several distinctions can be made based upon the location of a structure relative to this line: distinctionabove pectinate linebelow pectinate line lymph drainageinternal iliacsuperficial inguinal lymph nodes (below hilton's white line) epitheliumcolumnar epithelium (as is most of the digestive tract - the line represents the end of the part of the body derived from the hindgut)stratified squamous epithelium, non-keratinized (until hilton's white line, where the anal verge becomes continuous with the perianal skin containing keratinized epithelium.) embryological originendodermectoderm arterysuperior rectal arterymiddle and inferior rectal arteries veinsuperior rectal vein draining into the inferior mesenteric vein and subsequently the hepatic portal systemmiddle and inferior rectal veins hemorrhoids classificationinternal hemorrhoids (not painful)external hemorrhoids (painful) nervesinferior hypogastric plexuspudendal nerves additional images microscopic cross section of the anorectal junction. anatomy of the anus and rectum coronal section of rectum and anal canal.