cecum

The cecum is the beginning section of the large intestine and is a blind-ended pouch that receives chyme from the ileum through the ileocecal valve. In humans it is intraperitoneal and located in the lower right abdomen, though its position can vary with body habitus and colon fixation.

Anatomy and connections: The cecum is continuous with the ascending colon at the ileocecal junction. The ileocecal valve regulates flow from the ileum into the cecum and helps prevent backflow. The cecum is supplied by the ileocolic artery, a branch of the superior mesenteric artery, and drained by the ileocolic vein into the superior mesenteric vein. Its wall contains lymphoid tissue and mucosa with goblet cells; the region often harbors lymphatic tissue such as Peyer's patches.

Function: In humans, the cecum plays a relatively modest role in digestion, serving as a site for receiving chyme and as a microbial habitat. It participates in water and electrolyte absorption to a limited extent and hosts gut bacteria that ferment certain carbohydrates, producing short-chain fatty acids. In many herbivores and omnivores, the cecum is larger and serves as a major fermentation chamber.

Clinical relevance: The appendix develops from the inferior aspect of the cecum. Inflammation of the appendix (appendicitis) is a common clinical condition. Cancers can arise in the cecum, and diverticular disease is less common there than in the sigmoid colon. During colonoscopy, the cecum is used as a landmark for ileocecal intubation.