The cecum or caecum is a pouch within the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...

that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the

appendix Appendix, or its plural form appendices, may refer to: __NOTOC__ In documents * Addendum, an addition made to a document by its author after its initial printing or publication * Bibliography, a systematic list of books and other works * Index (pub ...

, to which it is joined). The word cecum (, plural ceca ) stems from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

'' caecus'' meaning blind. It receives

chyme Chyme or chymus (; from Greek χυμός ''khymos'', "juice") is the semi-fluid mass of partly digested food that is expelled by a person's stomach, through the pyloric valve, into the duodenumileum, and connects to the

ascending colon ''Ascending'' is a science fiction novel by the Canadian writer James Alan Gardner, published in 2001 by HarperCollins Publishers under its various imprints.HarperCollins, Avon, HarperCollins Canada, SFBC/Avon; paperback edition 2001, Eos Books. ...

of the large intestine. It is separated from the ileum by the ileocecal valve (ICV) or 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. In

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

s, 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.

Structure

Development

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

comes to lie on the medial side.

History

Etymology

The term ''cecum'' comes from Latin ''(intestinum) caecum'', literally 'blind intestine', in the sense 'blind gut' or '

cul de sac A dead end, also known as a cul-de-sac (, from French for 'bag-bottom'), no through road or no exit road, is a street with only one inlet or outlet. The term "dead end" is understood in all varieties of English, but the official terminology ...

'. It is a direct translation from Ancient Greek τυφλὸν (ἔντερον) ''typhlòn (énteron)''. Thus the inflammation of the cecum is called typhlitis. In

dissection Dissection (from Latin ' "to cut to pieces"; also called anatomization) is the dismembering of the body of a deceased animal or plant to study its anatomical structure. Autopsy is used in pathology and forensic medicine to determine the cause o ...

s by the Greek philosophers, the connection between the ileum of the

small intestine The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the p ...

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. 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 The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...

, to the

sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

, through the descending,

transverse Transverse may refer to: *Transverse engine, an engine in which the crankshaft is oriented side-to-side relative to the wheels of the vehicle *Transverse flute, a flute that is held horizontally * Transverse force (or ''Euler force''), the tangen ...

, and

ascending ''Ascending'' is a science fiction novel by the Canadian writer James Alan Gardner, published in 2001 by HarperCollins Publishers under its various imprints.HarperCollins, Avon, HarperCollins Canada, SFBC/Avon; paperback edition 2001, Eos Books. ...

sections. The cecum is an end point for the colon with a dead-end portion terminating with the

. 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 ileocolic 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 The appendix (or vermiform appendix; also cecal

r caecal R, or r, is the eighteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''ar'' (pronounced ), plural ''ars'', or in Irelan ...

appendix; vermix; or vermiform process) is a finger-like, blind-ended tube connected to the cecum, from which it prenatal development, develops in the embryo. The cecum is a pouch-like ...

(a carcinoid tumor of the appendix) is sometimes found next to a cecal carcinoid.

Neutropenic enterocolitis Neutropenic enterocolitis is inflammation of the cecum (part of the large intestine) that may be associated with infection. It is particularly associated with neutropenia, a low level of neutrophil granulocytes (the most common form of white blood ...

(typhlitis) is the condition of inflammation of the cecum, primarily caused by bacterial infections. Over 99% of the bacteria in the gut are

anaerobe An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenate ...

s,University of Glasgow. 2005.
The normal gut flora.
Available through web archive. Accessed May 22, 2008 but in the cecum, aerobic bacteria reach high densities.

Other animals

A cecum is present in most

amniote Amniotes are a clade of tetrapod vertebrates that comprises sauropsids (including all reptiles and birds, and extinct parareptiles and non-avian dinosaurs) and synapsids (including pelycosaurs and therapsids such as mammals). They are disti ...

species, and also in

lungfish Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

, but not in any living species of

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

. In

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s, it is usually a single median structure, arising from the dorsal side of the large intestine.

Bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s typically have two paired ceca, as do, unlike other mammals,

hyrax Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simil ...

es. Parrots do not have ceca. Most mammalian

s have a relatively large cecum, hosting a large number of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, which aid in the

enzymatic Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

breakdown of plant matter such as

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

; in many species, it is considerably wider than the colon. 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

. Mammalian species which do not develop a cecum include raccoons,

bear Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Nor ...

s, and the red panda. Many fish have a number of small outpockets, called ''pyloric ceca'', along their intestine; despite the name they are not

homologous Homology may refer to: Sciences Biology *Homology (biology), any characteristic of biological organisms that is derived from a common ancestor *Sequence homology, biological homology between DNA, RNA, or protein sequences * Homologous chrom ...

with the cecum of amniotes, and their purpose is to increase the overall area of the digestive epithelium. Some invertebrates, such as squid, may also have structures with the same name, but these have no relationship with those of vertebrates.

Gallery

File:Blausen 0604 LargeIntestine2.png, Illustration of the large intestine 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 An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

image of cecum with arrow pointing to ileocecal valve in foreground

References

External links

* —"Abdominal organs in situ." * —"The larger intestine." * —"The cecum with the distal portion of the ileum." * —"Incisions of the Cecum" *
Photo at mgccc.cc.ms.us

Video clip of worms in the Cecum
{{Authority control Digestive system Latin words and phrases