Cecum

The cecum or caecum (, plural ; from the Latin meaning blind) is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve (ICV) or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic junction. The appendix is connected to the cecum . The cecum is usually peritoneal, while the ascending colon is retroperitoneal .

Variation Across Species

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. Birds typically have two paired ceca, as, unlike other mammals, do hyraxes.

Most mammalian herbivores have a relatively large cecum, hosting a large number of bacteria, which aid in the enzymatic breakdown of plant materials such as cellulose; in many species, it is considerably wider than the colon. In contrast, obligatory carnivores, whose diets contain little or no plant material, have a reduced cecum, which is often partially or wholly replaced by the vermiform appendix. may also have structures with the same name, but these have no relationship with those of vertebrates.

Etymology

The term cecum comes from the Latin caecum, literally "blind", here in the sense "blind gut" or "cul de sac".

In dissections by the Greek philosophers, the connection between the ileum of the small intestines 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, to the sigmoid colon, through the descending, transverse, and ascending sections. The colon seemed to dead-end into the cecum, or cul-de-sac.

The connection between the end of the small intestine (ileum) and the start of the colon (cecum) is now clearly understood, but the name has not changed.

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 appendix comes to lie on the medial side.

Diseases

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

See also

McBurney's point

Additional images

References

External links

Photo at mgccc.cc.ms.us

- "Abdominal organs in situ." - "The larger intestine." - "The cecum with the distal portion of the ileum." - "Incisions of the Cecum"

Video clip of worms in the Cecum

Category:Digestive system