Sigmoid colon

Sigmoid colon
Sigmoid colon
Gray1223.png
Front of abdomen, showing surface markings for liver, stomach, and great intestine.
Latin colon sigmoideum
Gray's subject #249 1182
Artery sigmoid arteries
Nerve superior mesenteric ganglia, sacral nerve [1]
Precursor hindgut

The sigmoid colon (pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm. in length, and normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity.

Contents

Path

It begins at the superior aperture of the lesser pelvis, where it is continuous with the iliac colon, and passes transversely across the front of the sacrum to the right side of the pelvis. (The name sigmoid aptly means S-shaped.)

It then curves on itself and turns toward the left to reach the middle line at the level of the third piece of the sacrum, where it bends downward and ends in the rectum.

Coverings

It is completely surrounded by peritoneum (and thus is not retroperitoneal), which forms a mesentery (sigmoid mesocolon), which diminishes in length from the center toward the ends of the loop, where it disappears, so that the loop is fixed at its junctions with the iliac colon and rectum, but enjoys a considerable range of movement in its central portion.

Innervation

Pelvic splanchnic nerves are the primary source for parasympathetic innervation. Lumbar splanchnic nerves provide sympathetic innervation via the inferior mesenteric ganglion.

Relations

Behind the sigmoid colon are the external iliac vessels, the left Piriformis, and left sacral plexus of nerves.

In front, it is separated from the bladder in the male, and the uterus in the female, by some coils of the small intestine.

Additional images

References

  1. ^ Physiology at MCG 6/6ch2/s6ch2_30

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • sigmoid colon — n the contracted and crooked part of the colon immediately above the rectum called also pelvic colon, sigmoid flexure * * * the S shaped terminal part of the descending colon, which leads to the rectum. * * * colon sigmoideum [TA] the S shaped… …   Medical dictionary

  • sigmoid colon — sigmoid flexure the S shaped terminal part of the descending colon, which leads to the rectum …   The new mediacal dictionary

  • sigmoid colon — noun the s shaped curve between the descending colon and the rectum • Syn: ↑sigmoid flexure • Hypernyms: ↑colon • Part Holonyms: ↑large intestine …   Useful english dictionary

  • sigmoid colon — noun Date: 1896 the contracted and crooked part of the colon immediately above the rectum called also sigmoid flexure …   New Collegiate Dictionary

  • sigmoid colon — noun the S shaped section of the large intestine between the descending colon and the rectum Syn: sigmoid flexure …   Wiktionary

  • sigmoid colon — The S shaped section of the colon that connects to the rectum …   English dictionary of cancer terms

  • sigmoid colon — lower part of the large intestine that connects to the rectum (Anatomy) …   English contemporary dictionary

  • sigmoid flexure — sigmoid colon …   The new mediacal dictionary

  • sigmoid flexure — n sigmoid colon * * * see sigmoid colon * * * colon sigmoideum …   Medical dictionary

  • Sigmoid — means resembling the lower case Greek letter sigma (ς). Specific uses include:* Sigmoid function, a mathematical function * Sigmoid colon, part of the large intestine or colon …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”