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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.)
Details
Identifiers
Latin	linea pectinata, linea anocutanea
TA98	A05.7.05.009
TA2	3015
FMA	29321
Anatomical terminology [edit on Wikidata]

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.^[1] 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).^[1] Several distinctions can be made based upon the location of a structure relative to the pectinate line:

Distinction	Above pectinate line	Below pectinate line
Lymph drainage	internal iliac^[2]	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^[3]	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

Microscopic cross section of the anorectal junction
Anatomy of the anus and rectum
Coronal section of rectum and anal canal

References

^ ^a ^b Lee, JM; Kim, NK (April 2018). "Essential Anatomy of the Anorectum for Colorectal Surgeons Focused on the Gross Anatomy and Histologic Findings". Annals of coloproctology. 34 (2): 59–71. doi:10.3393/ac.2017.12.15. PMID 29742860.
^ 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.{{cite book}}: CS1 maint: multiple names: authors list (link)
^ Schoenwolf, Gary C.; Bleyl, Steven B.; Brauer, Philip R.; Francis-West, Philippa H. (2014-12-01). Larsen's Human Embryology. Elsevier Health Sciences. p. 372. ISBN 9781455727919.

External links

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

Anatomy of the gastrointestinal tract, excluding the mouth

Upper

Pharynx	Muscles Spaces peripharyngeal retropharyngeal parapharyngeal retrovisceral danger prevertebral Pterygomandibular raphe Pharyngeal raphe Buccopharyngeal fascia Pharyngobasilar fascia Pyriform sinus
Esophagus	Sphincters upper lower glands crop
Stomach	Curvatures greater lesser Angular incisure Cardia Body Fundus Pylorus Gastric mucosa Gastric folds Microanatomy Gastric pits Gastric glands Cardiac glands Fundic glands Pyloric glands Foveolar cells Parietal cells Gastric chief cells Enterochromaffin-like cells

Lower

Small intestine

Microanatomy	Intestinal villi Microvilli Intestinal glands Enterocytes Enteroendocrine cells Goblet cells Paneth cells
Duodenum	Suspensory muscle Major duodenal papilla Minor duodenal papilla Duodenojejunal flexure Brunner's glands
Jejunum	No substructures
Ileum	Ileocecal valve Peyer's patches Microfold cells

Large intestine

Cecum	Appendix
Colon	Ascending colon Hepatic flexure Transverse colon Splenic flexure Descending colon Sigmoid colon Continuous taenia coli haustra epiploic appendix
Rectum	Transverse folds Ampulla
Anal canal	Anus Anal columns Anal valves Anal sinuses Pectinate line Internal anal sphincter Intersphincteric groove External anal sphincter

Wall

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