Cecum

Overview
The cecum or caecum (from the Latin caecus meaning blind) is a pouch connected to the ascending colon of the large intestine and the ileum. 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.

Variation across species
The cecum is present in mammals, and two ceca are present in most birds, and some reptiles.

Most herbivores have a relatively large cecum, hosting a large number of bacteria, which aid in the enzymatic breakdown of plant materials such as cellulose.

Exclusive carnivores, whose diets contain little or no plant material, have a reduced cecum, often partially or wholly replaced by the vermiform appendix.

Etymology
The term cecum comes from the Latin, meaning 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 intestines 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.

However, the connection between the end of the small intestines, ileum, and the start of the colon, cecum are now clearly understood, but the name has not changed.