Topic Completed: 1 September 2014

Minor changes: 5 February 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Colon anatomy[title]

Hanni Gulwani, M.B.B.S.
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Cite this page: Gulwani H. Anatomy. website. Accessed April 18th, 2021.
Definition / general
  • 1.0 to 1.5 meters long, from terminal ileum to anal canal
  • Compared to small intestine, has greater diameter, fixed position, epiploic appendages, taeniae coli (discontinuous muscular fibers)

  • Cecum, ascending (right sided) colon, transverse colon, descending (left sided) colon, sigmoid colon, rectum

  • In peritoneum, 6 x 9 cm
  • Large blind pouch arising from proximal right colon
  • Blind end directed downward, open end directed upward

Ascending colon:
  • 15 - 20 cm long
  • Posterior surface is in retroperitoneum, but anterior and lateral surfaces have serosa and are intraperitoneal

Hepatic flexure:
  • Junction of ascending and transverse colon

Transverse colon:
  • Connects ascending colon at hepatic / right colic flexure to the descending colon at the splenic / left colic flexure (Wikipedia)

Splenic flexure:
  • Junction of transverse and descending colon

Descending colon:
  • 10 - 15 cm long
  • Posterior surface is in retroperitoneum, but anterior and lateral surfaces have serosa and are intraperitoneal

  • Descending colon at origin of mesosigmoid
  • From pelvic rim to S3 vertebra

  • 12 cm
  • Sigmoid colon from termination of mesosigmoid
  • Also from opposite sacral promontory to upper border of anal canal
  • Becomes extraperitoneal (within the pelvis) as it passes between crura of peritoneal muscles
  • Has no serosa / peritoneal covering

Pouch of Douglas:
  • Cul-de-sac in women made up of reflection of peritoneum from rectum over pelvic wall

Taenia coli:

Epiploic appendages:
  • Pedunculated fat on lateral colon
  • Lined by mesothelium

  • Superior mesenteric artery supplies cecum to splenic flexure
  • Inferior mesenteric artery supplies remainder of colon to rectum
  • Numerous collaterals connect mesenteric circulation with celiac arterial axis proximally and pudental circulation distally
  • Superior hemorrhoidal branch of inferior mesenteric artery supplies upper rectum; hemorrhoidal branches of internal iliac or internal pudental artery supplies lower rectum
  • Venous drainage is similar; there is an anastomotic capillary bed between the superior and inferior hemorrhoidal veins, providing a connection between the portal and venous systems (Surg Oncol 2006;15:243)
  • Primitive gut is divided into foregut, midgut, hindgut
  • Midgut gives rise to cecum, ascending colon and right 75% of transverse colon (also distal duodenum to ileum)
  • Hindgut develops into remainder of transverse colon to anorectal line
  • During week 6 of fetal development, endodermal epithelium of gut tube proliferates and completely occludes the lumen
  • Over the next two weeks, it vacuolates and recanalizes
  • Maturation of haustra and tenia coli start from ascending colon and progress towards sigmoid colon (Early Hum Dev 2004;78:1)
Diagrams / tables

Images hosted on other servers:

Regions of colon

Cecum and appendix

Cecum and ileocecal valve

Small and large intestine

Iliac, sigmoid or pelvic colon and rectum

Female pelvis

Vascular supply of colon

Microscopic (histologic) images

Contributed by Grigory Demyashkin, M.D., Ph.D.

6-8 week embryo

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