Sigmoid colon - wikipedia Sigmoid colon Sigmoid colon Drawing of colon seen from front ( sigmoid colon coloured blue ) Front of abdomen, showing surface markings for liver, stomach and large intestine Details Precursor Hindgut Artery Sigmoid arteries of inferior mesenteric artery Nerve Inferior mesenteric ganglia and sacral nerve Identifiers Latin Colon sigmoideum Dorlands / Elsevier 12249909 TA A05. 7.03. 007 FMA 14548 Anatomical terminology ( edit on Wikidata ) 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 35 - 40 cm in length. The loop is typically shaped like a Greek letter sigma ( ς ) or Latin letter S ( thus sigma + - oid ). This part of the colon normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity. Contents 1 Structure 1.1 Coverings 1.2 Innervation 1.3 Relations 2 Clinical significance 3 Additional images 4 References 5 External links Structure The sigmoid colon 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. Its function is to expel solid and gaseous waste from the gastrointestinal tract. The curving path it takes toward the anus allows it to store gas in the superior arched portion, enabling the colon to expel gas without excreting faeces simultaneously. 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. Clinical significance This section needs expansion. You can help by adding to it. ( February 2014 ) Diverticulosis often occurs in the sigmoid colon in association with increased intraluminal pressure and focal weakness in the colonic wall. It is a common cause of hematochezia. Volvulus occurs when a portion of the bowel twists around its mesentery, which can lead to obstruction and infarction. Volvulus in the elderly commonly occurs in the sigmoid colon, whereas in infants and children it is more likely to occur in the midgut. This may correct itself spontaneously or the rotation may continue until the blood supply of the gut is cut off completely. Additional images 1 : Ascending colon 2 : Transverse colon 3 : Descending colon 4 : Sigmoid colon 5 : Rectum 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 This article incorporates text in the public domain from the 20th edition of Gray 's Anatomy ( 1918 ) Jump up ^ Physiology : 6 / 6ch2 / s6ch2_30 - Essentials of Human Physiology External links Wikimedia Commons has media related to Sigmoid colon. Anatomy figure : 37 : 06 - 07 at Human Anatomy Online, SUNY Downstate Medical Center - `` The large intestine. '' Superior & Inferior Mesenteric Artery at The Anatomy Lesson by Wesley Norman ( Georgetown University ) 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 Piriform sinus Esophagus Sphincters upper lower glands Stomach Curvatures greater lesser Angular incisure Cardia Body Fundus Pylorus antrum canal sphincter Gastric mucosa Gastric folds Microanatomy Gastric pits Gastric glands Cardiac glands Fundic glands Pyloric glands Foveolar cell Parietal cell Gastric chief cell Enterochromaffin - like cell Lower Small intestine Microanatomy Intestinal villus Intestinal gland Enterocyte Enteroendocrine cell Goblet cell Paneth cell Duodenum Suspensory muscle Major duodenal papilla Minor duodenal papilla Duodenojejunal flexure Brunner 's glands Jejunum No substructures Ileum Ileocecal valve Peyer 's patches Microfold cell 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 Serosa / Adventitia Subserosa Muscular layer Submucosa Circular folds Mucosa Muscularis mucosa Retrieved from `` https://en.wikipedia.org/w/index.php?title=Sigmoid_colon&oldid=783410072 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Digestive system Colon ( anatomy ) Hidden categories : Medicine infobox template using GraySubject or GrayPage Medicine infobox template using Dorlands parameter All articles with unsourced statements Articles with unsourced statements from March 2014 Articles to be expanded from February 2014 All articles to be expanded Articles using small message boxes Talk Contents About Wikipedia Dansk Deutsch ދިވެހިބަސް فارسی Français Italiano Latina Lietuvių Nederlands Polski Português Русский Svenska Українська 中文 Edit links This page was last edited on 2 June 2017, at 03 : 06. 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Question: is the sigmoid colon part of the large or small intestine
Answer: the large intestine