Cecum and vermiform appendix

Author: Achudhan Karunaharamoorthy, MD • Reviewer: Dimitrios Mytilinaios, MD, PhD
Last reviewed: October 30, 2023
Reading time: 7 minutes

The cecum is the first part of the large intestine. It is intraperitoneal, beginning caudally from the ileocecal valve and ending blindly in the right iliac fossa. The cecum exhibits similar distinguishing features like the rest of the colon (taeniae, haustra, semilunar folds), except appendices epiploicae. The cecum receives arterial blood from the cecal arteries.

The vermiform appendix is attached dorsomedially to the end of the cecum. It lies intraperitoneally, most commonly retrocecally or alternatively, in the lesser pelvis. In contrast to the cecum and the rest of the colon, the appendix lacks taeniae, haustra, semilunar folds and appendices epiploicae. The appendix is supplied by the appendicular artery.

Key facts about the cecum and appendix
Cecum	Clinical variations: mobile, free, fixed cecum Histology: mucosa (columnar epithelium), submucosa, muscularis, serosa Blood supply: cecal arteries and veins Innervation: superior mesenteric plexus and vagus nerve
Appendix	Common locations: retrocecal or lesser pelvis Histology: mucosa, submucosa (lymph follicles and parafollicular tissue), muscularis, serosa Blood supply: appendicular arteries and veins Innervation: superior mesenteric plexus and vagus nerve

Contents

Macroscopic anatomy
Microscopic anatomy
Function
1. Cecum
2. Appendix
Appendicitis
Sources

+ Show all

Macroscopic anatomy

Large intestine (diagram)

Cecum

Typically, the cecum is located intraperitoneally in the right lower abdomen and has a length of 5 to 7 cm. However, due to an incomplete rotation of the umbilical loop during embryogenesis it may lie quite variably. Therefore clinically, one differentiates between three important variations:

mobile cecum (completely covered by peritoneum)
free cecum (with its own mesocecum)
fixed cecum (secondary retroperitoneal)

As in the colon, taeniae, haustra and semilunar folds are found in the cecum but no appendices epiploicae.

The cecum is supplied by the anterior and posterior cecal arteries. The venous blood drains through the correspondent veins into the superior mesenteric vein. The cecum is innervated by the superior mesenteric plexus, whereas the parasympathetic fibers come from the vagus nerve (cranial nerve X).

Vermiform appendix

The vermiform appendix is attached dorsomedially to the end of the cecum, where all three taeniae converge. It is 2 to 15 cm long and lies often intraperitoneally retrocecal (65%) or in the lesser pelvis (30%). The appendix is attached to the posterior abdominal wall by the mesoappendix. Here taeniae, haustra, semilunar folds and appendices epiploicae are all absent.

The appendix is supplied by the appendicular artery (all branches of the ileocolic artery from the superior mesenteric artery). The venous blood drains through the correspondent veins into the superior mesenteric vein. Similar to the cecum, the appendix is innervated by the superior mesenteric plexus, whereas the parasympathetic fibers come from the vagus nerve (cranial nerve X).

Cecum and appendix in a cadaver: When dissecting the large intestine, slice the anterior wall of the cecum to identify some of its internal features. For example, the ileocecal valve, ileocecal orifice and the opening of the appendix. They are located on the medial aspect of the cecum.

Microscopic anatomy

The microscopic structure of the cecum is equal to that of the colon:

Mucosa - columnar epithelium with crypts, contains goblet and endocrine cells
Submucosa - with blood vessels and lymph nodes
Muscularis - strongly pronounced inner circular musculature, outer longitudinal musculature almost restricted to the taeniae
Serosa/Adventitia

Histologically the appendix looks quite similar to the colon and cecum. A distinctive feature is however the numerous lymph follicles and the parafollicular tissue in the connective tissue layer of the mucosa (lamina propriae mucosae) and the submucosa. The crypts are particularly deep so that the follicles are in close contact to the intestinal lumen. M-cells (microfold cells) are found in the epithelium which access antigens from the intestinal lumen. As the appendix lacks taeniae it has a regular outer longitudinal musculature.

Function

Cecum

The main tasks of the cecum are the absorption of water and salts and the lubrication of the feces with mucus. Especially components from plant-rich food (e.g. cellulose) are bacterially decomposed here. This explains why herbivores have considerably larger ceca in comparison to carnivores.

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Appendix

The appendix is part of the GALT (gut-associated lymphatic tissue) and fulfills immunological functions. Furthermore it is assumed that it serves as a “safe house” for enterobacteria (e.g. in case of diarrhea). On the picture you can see an inflamed vermiform appendix which was removed operatively.

More details about the anatomy and histology of the cecum and appendix are included below:

Appendicitis

As the name implies, this condition involves the inflammation of the appendix. The main cause of appendicitis is a blockage of the appendix itself, often due to faecal matter, an infection, foreign body or a tumour. As a result, the appendix can burst or perforate if left untreated. It is a very dangerous condition that is considered a medical emergency due to potential severe complications, like peritonitis, if it is not managed.

Acute appendicitis

The signs and symptoms of appendicitis include:

pain that extends from the navel (dull) towards the lower-right portion of the abdomen (sharp)
loss of appetite
nausea and vomiting
abdominal swelling
fever

The majority of time, treatment of appendicitis involves an appendectomy (removal of the appendix).

Sources

All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is grounded on academic literature and peer-reviewed research. Kenhub does not provide medical advice. You can learn more about our content creation and review standards by reading our content quality guidelines.

References:

D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1.Auflage, Urban & Fischer Verlag/Elsevier (2008), S.269
U. Welsch: Lehrbuch Histologie, 2.Auflage, Urban & Fischer Verlag/Elsevier (2006), S.383-384
K. Zilles/B.Tillmann: Anatomie, 1.Auflage, Springer Medizin Verlag (2010), S.476-480
M. Müller: Chirurgie – für Studium und Praxis 2012/13, Medizinische Verlags- und Informationsdienste (2011), S.192
Bollinger: Biofilms in the large bowel suggest an apparent function of the human vermiform appendix, Theoretical Biology - Volume 249 (2007), S.826-831
WebMD: Appendicitis, accessed on 19/06/2017

Illustrators:

Large intestine (diagram) - Begoña Rodriguez
Acute appendicitis - Photo: Flickr / euthman
Cecum and appendix in a cadaver - Prof. Carlos Suárez-Quian

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Cecum and vermiform appendix

Macroscopic anatomy

Cecum

Vermiform appendix

Microscopic anatomy

Function

Cecum

Appendix

Appendicitis

Sources

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