Cecum

{{short description|Pouch in the large intestine}} {{Redirect|Caecum|the genus of sea snails|Caecum (genus)|other taxonomic uses|List of Latin and Greek words commonly used in systematic names}} {{Distinguish|sacrum}}

{{Infobox anatomy | Name = Cecum | Latin = caecum | Image = Tractus intestinalis cecum.svg | Caption = The cecum, here in red, lies at the start of the large intestine, which is shown with the rest of the human gastrointestinal tract in this image. | Width = | Image2 = Gray1043.png | Caption2 = Superior ileocecal fossa<br />(cecum labeled at bottom left) | Precursor = Midgut | System = Gastrointestinal | Artery = | Vein = | Nerve = | Lymph = | PartOf = Large intestine | Location = Lower right part of the abdomen }}

The '''cecum''' ({{small|UK:}} '''caecum''', {{small|pronounced}} {{IPAc-en|ˈ|s|iː|.|k|əm}}; plural '''ceca''' or {{small|UK:}} '''caeca''', {{small|pronounced}} {{IPAc-en|ˈ|s|iː|.|k|ə}}) is a pouch within the peritoneum that is considered to be the beginning of the large intestine.<ref name="Stedman 2000 p. ">{{cite book |last=Stedman |first=Thomas |title=Stedman's medical dictionary |publisher=Lippincott Williams & Wilkins |publication-place=Philadelphia |year=2000 |isbn=978-0-683-40007-6 |oclc=42772946 |page=915 |quote='''large i[ntestine]''', the portion of the digestive tube extending from the ileocecal valve to the anus; it comprises the cecum, colon, rectum, and anal canal}}</ref> It is typically located on the right side of the body (the same side of the body as the appendix, to which it is joined). The term stems from the Latin ''caecus'', meaning "blind".

It receives chyme from the ileum, and connects to the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve (ICV), also called Bauhin's valve. It is also separated from the colon by the cecocolic junction. While the cecum is usually intraperitoneal, the ascending colon is retroperitoneal.<ref>{{cite web |url=https://download.videohelp.com/vitualis/med/large_intestine.htm |title=The Large Intestine |publisher=VideoHelp.com}}</ref>

In herbivores, the cecum stores food material where bacteria are able to break down the cellulose. In humans, the cecum is involved in absorption of salts and electrolytes and lubricates the solid waste that passes into the large intestine.<ref>{{Cite web |url=https://www.sciencing.com/functions-cecum-6809336/ |title=What Are the Functions of the Cecum?}}</ref>

==Structure== thumb|Inner diameters of different sections of the large intestine, with cecum (at bottom left) measuring on average 8.7 cm (range 8.0-10.5 cm).<ref name=Nguyen>{{cite journal |vauthors=Nguyen H, Loustaunau C, Facista A, Ramsey L, Hassounah N, Taylor H, Krouse R, Payne CM, Tsikitis VL, Goldschmid S, Banerjee B, Perini RF, Bernstein C |title=Deficient Pms2, ERCC1, Ku86, CcOI in field defects during progression to colon cancer |journal=J Vis Exp |issue=41 |year=2010 |pmid=20689513 |pmc=3149991 |doi=10.3791/1931 }}</ref>

===Development=== The cecum and appendix are derived from the bud of cecum that forms during week six in the midgut next to the apex of the umbilical herniation.<ref name="lie">{{cite journal |last1=Kostouros |first1=Antonios |last2=Koliarakis |first2=Ioannis |last3=Natsis |first3=Konstantinos |last4=Spandidos |first4=Demetrios |last5=Tsatsakis |first5=Aristidis |last6=Tsiaoussis |first6=John |title=Large intestine embryogenesis: Molecular pathways and related disorders (Review) |journal=International Journal of Molecular Medicine |date=21 April 2020 |volume=46 |issue=1 |pages=27–57 |doi=10.3892/ijmm.2020.4583 |pmid=32319546 |pmc=7255481 }}</ref> Specifically, the cecum and appendix are formed by the enlargement of the postarterial segment of the midgut loop. The proximal part of the bud grows rapidly to form the cecum. The lateral wall of the cecum grows much more rapidly than the medial wall, with the result that the point of attachment of the appendix comes to lie on the medial side.{{Citation needed|date=May 2011}} The cecum's position changes after the midgut rotates and the ascending colon elongates, and the accumulation of meconium inside the cecum may result in the latter's increased diameter.<ref name="lie"/>

==History== ===Etymology=== The term ''cecum'' comes from Latin ''(intestinum) caecum'', literally 'blind intestine', in the sense 'blind gut' or 'cul de sac'.<ref>{{Cite web |title=Caecum - Etymology, Origin, and Meaning |url=https://www.etymonline.com/word/caecum |access-date=2022-05-27 |website=etymonline.com |language=en}}</ref> It is a direct translation from Ancient Greek {{lang|grc|τυφλὸν}} ({{lang|grc|ἔντερον}}) {{transliteration|grc|typhlòn}} ({{transliteration|grc|énteron}}). Thus the inflammation of the cecum is called typhlitis.

In dissections by the Greek philosophers, the connection between the ileum of the small intestine and the cecum was not fully understood. Most of the studies of the digestive tract were done on animals and the results were compared to human structures.<ref>{{Cite web |title=Ileum |url=https://www.kenhub.com/en/library/anatomy/the-ileum |access-date=2022-06-18 |website=Kenhub |language=en}}</ref>

The junction between the small intestine and the colon, called the ileocecal valve, is so small in some animals that it was not considered to be a connection between the small and large intestines. During a dissection, the colon could be traced from the rectum, to the sigmoid colon, through the descending, transverse, and ascending sections. The cecum is an end point for the colon with a dead-end portion terminating with the appendix.<ref>{{cite web |last1=Taylor |first1=Tim |title=Anatomy and Physiology Instructor |url=https://www.innerbody.com/image/dige08.html |website=InnerBody.com |publisher=Howtomedia, Inc. |access-date=28 November 2014}}</ref>

The connection between the end of the small intestine (ileum) and the start (as viewed from the perspective of food being processed) of the colon (cecum) is now clearly understood, and is called the ileocecal orifice. The connection between the end of the cecum and the beginning of the ascending colon is called the cecocolic orifice.

==Clinical significance== A cecal carcinoid tumor is a carcinoid tumor of the cecum. An appendiceal carcinoid tumor (a carcinoid tumor of the appendix) is sometimes found next to a cecal carcinoid.<ref>{{Cite journal |last1=Salirrosas Roncal |first1=Oscar A |last2=Tantalean Gutierrez |first2=Christian |last3=Llerena Vasquez |first3=Cesar |title=Carcinoid Tumor of the Cecal Appendix |journal=Cureus |date=2022 |volume=14 |issue=10 |article-number=e30793 |doi=10.7759/cureus.30793 |doi-access=free |issn=2168-8184 |pmc=9701446 |pmid=36447686}}</ref>

Neutropenic enterocolitis (typhlitis) is the condition of inflammation of the cecum, primarily caused by bacterial infections.

Over 99% of the bacteria in the gut are anaerobes<ref name="Guarner and Malagelada 2003b">{{cite journal |author=Guarner F, Malagelada JR |title=Gut flora in health and disease |journal=Lancet |volume=361 |issue=9356 |pages=512–19 |date=February 2003 |pmid=12583961 |doi=10.1016/S0140-6736(03)12489-0 |s2cid=38767655}}</ref><ref name=Sears>{{cite journal |author=Sears CL |title=A dynamic partnership: celebrating our gut flora |journal=Anaerobe |volume=11 |issue=5 |pages=247–51 |date=October 2005 |pmid=16701579 |doi=10.1016/j.anaerobe.2005.05.001}}</ref><ref name="University of Glasgow">University of Glasgow. 2005. [https://web.archive.org/web/20040526195616/http://www.gla.ac.uk/departments/humannutrition/students/resources/meden/Infection.pdf The normal gut flora.] Available through web archive. Accessed May 22, 2008</ref><ref name="Beaugerie L and Petit JC">{{cite journal |author=Beaugerie L, Petit JC |title=Microbial-gut interactions in health and disease. Antibiotic-associated diarrhoea |journal=Best Pract Res Clin Gastroenterol |volume=18 |issue=2 |pages=337–52 |date=April 2004 |pmid=15123074 |doi=10.1016/j.bpg.2003.10.002}}</ref><ref name=Vedantam>{{cite journal |author=Vedantam G, Hecht DW |title=Antibiotics and anaerobes of gut origin |journal=Curr. Opin. Microbiol. |volume=6 |issue=5 |pages=457–61 |date=October 2003 |pmid=14572537 |doi=10.1016/j.mib.2003.09.006}}</ref> but, in the cecum, aerobic bacteria reach high densities.<ref name="Prescotts">{{cite book |last2=Willey |first2=Joanne |last1=Sherwood |first1=Linda |last3=Woolverton |first3=Christopher |title=Prescott's Microbiology |url={{google books |plainurl=y |id=sBCSRAAACAAJ}} |year=2013 |isbn=978-0-07-340240-6 |publisher=McGraw Hill |location=New York |edition=9th |pages=713–21 |oclc=886600661}}</ref>

==Other animals== [[File:Gastric caeca of dissected cockroach.tiff|thumb|Gastric cecum of dissected cockroach. Scale bar, 2 mm.]]

A cecum is present in most amniote species, and also in lungfish, but not in any living species of amphibian. In reptiles, it is usually a single median structure, arising from the dorsal side of the large intestine. The ceca in birds are often paired, with many exceptions; parrots, for example, do not have ceca, while others may have a single cecum or even two pairs, like the secretarybird.<ref name=MP>{{cite journal |last1=Clench |first1=Mary H. |last2=Mathias |first2=John R. |title=The Avian Cecum: A Review |journal=The Wilson Bulletin |date=1995 |volume=107 |issue=1 |pages=93–121 |id={{Gale|A16787963}} {{INIST|3480481}} |jstor=4163516}}</ref>

Most mammalian herbivores have a relatively large cecum. In many species, it is considerably wider than the colon. For some herbivores such as lagomorphs (rabbits, hares, pikas), easily digestible food is processed in the gastrointestinal tract and expelled as regular feces. But in order to get nutrients out of hard-to-digest fiber, lagomorphs ferment fiber in the cecum and then expel the contents as cecotropes, which are reingested (cecotrophy). The cecotropes are then absorbed in the small intestine to utilize the nutrients.

In contrast, obligate carnivores, whose diets contain little or no plant matter, have a reduced cecum, which is often partially or wholly replaced by the appendix.<ref name=VB/> Mammalian species which do not develop a cecum include raccoons,<ref>{{cite journal |last1=Clemens |first1=Edgar T. |last2=Stevens |first2=Charles E. |title=Sites of Organic Acid Production and Patterns of Digesta Movement in the Gastro-Intestinal Tract of the Raccoon |journal=The Journal of Nutrition |date=1 June 1979 |volume=109 |issue=6 |pages=1110–1116 |doi=10.1093/jn/109.6.1110 |pmid=448450 |url=https://www.sciencedirect.com/science/article/abs/pii/S0022316623277147 |access-date=1 June 2024 |issn=0022-3166 |url-access=subscription}}</ref> bears,<ref>{{cite journal |last1=Jones |first1=James D. |last2=Zollman |first2=Paul E. |title=Black Bear (Ursus americanus) Bile Composition: Seasonal Changes |journal=Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology |date=17 March 1997 |volume=118 |issue=3 |pages=387–390 |doi=10.1016/S0742-8413(97)00176-X |pmid=9467890 |url=https://www.sciencedirect.com/science/article/abs/pii/S074284139700176X |access-date=1 June 2024 |url-access=subscription}}</ref> and the red panda.<ref>{{cite journal |last1=Wei |first1=F. |last2=Feng |first2=Z. |last3=Wang |first3=Z. |last4=Zhou |first4=A. |last5=Hu |first5=J. |title=Nutrient and energy requirements of red panda (Ailurus fulgens) during lactation |journal=Mamm |date=1 January 1999 |volume=63 |issue=1 |pages=3–10 |doi=10.1515/mamm.1999.63.1.3 |url=https://www.degruyterbrill.com/document/doi/10.1515/mamm.1999.63.1.3/html |access-date=1 June 2024 |language=en |issn=1864-1547 |url-access=subscription}}</ref> Hyraxes, unlike other mammals, have two paired ceca.<ref name=VB>{{cite book |last1=Romer |first1=Alfred Sherwood |last2=Parsons |first2=Thomas S. |year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location=Philadelphia |pages=353–54 |isbn=978-0-03-910284-5}}</ref>

Many fish have a number of small outpockets, called ''pyloric ceca'', along their intestine; despite the name, they are not homologous with the cecum of amniotes – their function is to increase the overall area of the digestive epithelium.<ref name=VB/> Some invertebrates, such as squid,<ref name=Williams1910>{{cite book |last1=Williams |first1=Leonard Worcester |title=The anatomy of the common squid: ''Loligo pealii'', Lesueur |date=1910 |doi=10.5962/bhl.title.27291 |oclc=697639284 |url=https://www.biodiversitylibrary.org/item/69772}}</ref> may also have structures with the same name, but these have no relationship with those of vertebrates.

==Gallery== <gallery> File:Blausen 0604 LargeIntestine2.png|Illustration of the large intestine File:Monogastric Digestive System.webp|Illustration of human and rabbit cecum File:Cecum and ileum.JPG|Cecum and ileum File:Ileo-cecal valve.JPG|Ileo-cecal valve File:Cecum and ileocecal valve.JPG|Cecum File:Gray536.png|Arteries of cecum and vermiform process File:Gray1044.png|Inferior ileocecal fossa File:Ileocecal valve.jpg|Endoscopic image of cecum with arrow pointing to ileocecal valve in foreground </gallery>

==See also== * McBurney's point

==References== {{Reflist}}

==External links== {{Commons category|Cecum}} {{Wiktionary|cecum}} * {{SUNYAnatomyFigs|37|03|08}}—"Abdominal organs in situ" * {{SUNYAnatomyFigs|37|06|09}}—"The larger intestine" * {{SUNYAnatomyFigs|39|05|09}}—"The cecum with the distal portion of the ileum" * {{SUNYAnatomyLabs|39|14|01|01}}—"Incisions of the Cecum" * {{ViennaCrossSection|pelvis/pelvis-e12-2}} * [https://web.archive.org/web/20060715020910/http://learning.mgccc.cc.ms.us/science/cat/sld021.htm Photo at mgccc.cc.ms.us] * {{Webarchive |title=Video clip of worms in the Cecum - N Engl J Med 2006;354(13):e12 |url=https://web.archive.org/web/20100129103841/http://content.nejm.org/cgi/content/full/354/13/e12/DC1 |date=2010-01-29}} (Supplement to {{doi|10.1056/NEJMicm040931}})

{{Gastrointestinal tract}} {{Authority control}}

Category:Digestive system Category:Latin words and phrases