The cecum is the initial part of the large intestine that lies in the right iliac fossa. It is located intraperitoneally and has various folds and pockets surrounding it.

The cecum opens with the ileocecal orifice and is a continuation of the ileum. The terminal ileum ends, and the cecum begins at the ileocolic junction.

The ileocecal orifice is marked by the ileal papilla, formed by two folds called ileocecal lips. There is a superior and an inferior ileocecal lip. These lips fuse to form the frenula of the ileocecal orifice, which prevents reflux of cecal contents into the ileum.

There is also an ileocecal valve that regulates the passage of intestinal contents from the small into the large intestine.

The main functions of the cecum are the following: temporary storage of chyme, as well as fluid and electrolyte absorption.

The vermiform appendix arises from the cecum and is a narrow, hollow, blind lymphoid pouch. It is located in the right iliac fossa. The appendix is connected to the cecum by the mesoappendix, which contains the appendicular vessels.

Its point of attachment to the cecum is consistent, while the location of the rest of the appendix varies considerably. Some of its possible positions are as follows:

Retrocecal position - the appendix is located posterior to the cecum; this is also known as the posterior location, and the appendix may reach the posterior surface of the lower portion of the ascending colon (retrocolic position);
Para-cecal position - goes along the lateral surface of the cecum;
Pelvic or descending position - suspended over the pelvic brim (edge of the pelvic inlet), the appendix passes downward in the direction of the lesser pelvis;
Sub-cecal position - below the cecum;
Pre-ileal position - anterior to the terminal ileum, possibly contacting the body wall;
Postileal position - posterior to the terminal ileum;
Sub-ileal position - parallel to the terminal ileum;
Anterior location - located along the anterior surface of the cecum.

The appendix plays a role in the mucosal immunity and maintenance of the gut microbiome.

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Cecum and appendix