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| Sigmoid colon | |
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| 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 |
| Dorlands/Elsevier | c_47/12249909 |
The sigmoid colon (pelvic colon; sigmoid flexure) forms a loop which 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.
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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.
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. According to Isaac Asimov's book The Human Body, the name sigmoid means "S-shaped."
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.
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
 Intestines |
 Sigmoid colon and rectum, showing distribution of branches of inferior mesenteric artery and their anastomoses. |
 Iliac colon, sigmoid or pelvic colon, and rectum seen from the front, after removal of pubic bones and bladder. |
 Sagittal section of the lower part of a female trunk, right segment. |
References
External links
- Sigmoid+colon at eMedicine Dictionary
- SUNY Figs 37:06-07 - "The large intestine."
- Norman/Georgetown sup&infmesentericart
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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Wikipedia content modification information:
- This page was last modified on 1 July 2008, at 21:31.
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