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Caecum

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An Introduction of Caecum

IVSAT 2024

Our digestive system is made of different organs and the intestinal tract. It is actually a huge tract that starts from the mouth and ends in the rectal region. The intestines start from the pyloric end of the stomach and end in the rectal part. The first part of the large intestine is called the caecum. In this article, we will study what it is and how it differs from the rest of the intestinal sections.


What is the Large Intestine?

To understand what is caecum, we need to define the large intestine first. It is the thickest tube of the gastro-esophageal tract that originates at the end of the ileum of the small intestine and ends in the rectum is called the large intestine. This part of the digestive tract carries the waste products of digestion. It performs electrolyte and water reabsorption to maintain the fluidity of the blood and its electrolytic balance.


What is Caecum?

As mentioned earlier, the long tube-like structure present in the end part of the gastro-esophageal tract is called the large intestine. The primary section of this long tube is called the caecum. In other words, it can be described as the proximal part located between the ascending colon of the large intestine and the ileum, the last part of the small intestine.


According to the caecum location, it is the entry point of the digested chyme from the small intestine to the large intestine. The ileum of the small intestine unloads the intestinal content in the large intestine here. The large intestine is actually a reservoir for the chyme produced after the elaborate digestion in the small intestine.


Here, water and electrolytes are reabsorbed into the circulatory system to maintain the electrolytic balance of the blood. As per the biologists, it was the site for cellulose digestion in the digestive system of our ancestors. It can be considered as a vestigial organ if this function is considered. As we have changed our nutritional and dietary habits, this part of the large intestine has significantly lost its prime functions.


The Anatomical Structure of Caecum

As mentioned earlier, the first portion of the large intestine is the caecum. This part can be located in the right iliac fossa of the abdominal cavity. It is present right after the ileocaecal junction where the small intestine ends and the large intestine begins.


As per its anatomical shape, the caecum in humans is called the blind end at its inferior portion. It means that the junction is not at its tip but at its neck. The superior part is then continued to form the ascending colon, the second portion of the large intestine.


Its name has been derived from ‘caecus’, a Latin word that means ‘blind’. As it is the inferior blind part of the large intestine, it is termed caecum. It is present inside the peritoneum as it is covered from all sides. This is why it is intraperitoneal whereas the rest of the large intestine is retroperitoneal. It also has a variable mesenteric formation to keep it in its place.


A valve is there at the junction of the ileum and caecum called the ileocecal valve. This valve stops the small intestinal content from flowing back to the small intestine. It also stops the large intestinal content from entering the small intestine while generating bowel pressure.


Function of Caecum

The main caecum function is to absorb electrolytes and fluid from the small intestinal content flowing into form fecal matter. It is the last stage of intestinal digestion where the small intestine unloads its chyme into the large intestine for the final absorption process. In this phase, the caecum starts to draw water and salts from the content and increases its density.


The second most important function according to caecum location is to mix the large intestinal content with mucus to form a slimy bolus of fecal matter for easier defecation. It is done by the mucus membrane present on the inner caecum lining. The muscles underneath this membrane enable the movement of the digested boluses by performing kneading and churning motions. These are the prime caecum function in digestive system.


Difference Between Caecum and Colon

The colon, as we all know, is the retroperitoneal part of the large intestine residing outside the peritoneum within the abdominal cavity. On the other hand, the caecum is intraperitoneal. It means that it is entirely covered by the peritoneum and contains a variety of mesenteries for protection.


In terms of function, the caecum acts as the entry portion of the small intestinal content through the ileocaecal valve. The colon is the continuation of the caecum. Their physiological functions are similar. The vestigial function of the caecum was to digest cellulose. When our ancestors used to eat raw leaves and other plant parts, this part aided in digesting cellulose. Now that we have changed our food habits, this function, as well as, the size of the caecum has reduced.


This section of caecum vs colon has described the similarities and differences of these two large intestinal parts in terms of location and functions.


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This is a brief description of the caecum, its structural features, and its functions in the digestive system of the human body. Follow the caecum diagram to understand the morphology, position, and significance of this organ in the gastrointestinal tract.

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FAQs on Caecum

1. What is foramen caecum?

It might sound similar to that of the first segment of the large intestine but it is a crest or tract present between the nasal space and the anterior cranial fossa. It is not a part of the large intestine rather a significant part of the human nose. 

2. How does caecum knead and churn intestinal content?

One caecum function is to churn, turn, and knead the large intestinal content to mix it with mucus and to form a bolus for easy movement of the fecal matter. It is done by the involuntary muscles present underneath the mucus membrane present on the inner lining of the caecum. This action happens automatically to add more mucus for easy bowel movement.


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