Biology:Pectinate line

From HandWiki
Short description: Line dividing the upper two-thirds and the lower third of the anal canal
Pectinate line
Pectinate 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.)
LatinLinea pectinata, linea anocutanea
Anatomical terminology

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 several distinctions can be made based upon the location of a structure relative to this line:

Distinction Above pectinate line Below pectinate line
Lymph drainage internal iliac[1] superficial inguinal lymph nodes (below Hilton's white line)
Epithelium columnar 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 origin[2] endoderm ectoderm
Artery superior rectal artery middle and inferior rectal arteries
Vein superior rectal vein draining into the inferior mesenteric vein and subsequently the hepatic portal system middle and inferior rectal veins
Hemorrhoids classification internal hemorrhoids (not painful) external hemorrhoids (painful)
Nerves inferior hypogastric plexus pudendal nerves

Additional images


  1. MD, Tao Le, MD, MHS, Vikas Bhushan, MD, Matthew Sochat, MD (2017). First aid for the USMLE step 1 2017 : a student-to-student guide. ISBN 978-0071831420. 
  2. Schoenwolf, Gary C.; Bleyl, Steven B.; Brauer, Philip R.; Francis-West, Philippa H. (2014-12-01) (in en). Larsen's Human Embryology. Elsevier Health Sciences. pp. 372. ISBN 9781455727919. 

External links

  • pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University) (rectum)