Colon nontumor
Normal anatomy

Topic Completed: 1 September 2014

Revised: 7 January 2019, last major update September 2014

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Colon anatomy[title]

Hanni Gulwani, M.B.B.S.
Page views in 2018: 869
Page views in 2019 to date: 1,056
Cite this page: Gulwani H. Normal anatomy. website. Accessed November 17th, 2019.
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)
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

Clinical images

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Epiploic appendages
(see tip of pointer)

Microscopic (histologic) images

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Taenia coli and lymphoid tissue

Taenia coli: transverse section

Taenia coli: relationship to muscularis propria

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