Caecum - Anatomy & Physiology

ALIMENTARY SYSTEM LARGE INTESTINE

Introduction

Dog caecum, ileum and colon - © RVC 2008

Gibbon caecum and appendix- © RVC 2008

The caecum is a blind ending diverticulum of the large intestine and it exists at the junction of the ileum and the ascending colon. It's size and physiological importance vary between species. It is a site of microbial fermentation, absorption and transportation.

Structure

• It communicates with the ileum via the ileal orifice and with the colon via the caecocolic orifice.
• It consists of a base, body and apex, the apex being the blind-ending portion.
• It is attached to the ileum by a fold of peritoneum called the ileocaecal fold.

Function

Microbial Fermentation

• The contribution of this is species dependant. The products of fermentation are VFAs.

Absorption

• VFAs that are produced are absorbed here.

Transportation

• Segmental contractions facilitate absorption and microbial actitivity.
• Every 3-5 minutes, segmentation is replaced by mass movements. This is similar to peristalsis, but large portions of the caecum contract simultaneously to move chyme into the colon.

Histology

• No villi
• Mucosa has mucous glands
• Lamina muscularis has large lymphatic nodules.
• Submucosa has no glands.

Species Differences

Canine

• On the right side of the abdomen.
• Unique because it has no direct connection to the ileum.
• Short and held in a spiral shape against the ileum by the ileocaecal fold.
• Little microbial fermentation takes place.

Ruminant

• On the right side of the abdomen in the supraomental recess
• The apex points caudally.
• Relatively small and featureless: there are no taenia or haustra.
• Some microbial fermentation takes place.

Equine

• A significant amount of fermentation takes place.

Porcine

• On the left side of the abdomen, with the apex pointing caudoventrally.
• Cylindrical in shape.
• Three taenia are present
  • The ventral taenia provides the attachment for the ileocaecal fold.
  • The lateral and medial taenia are free.

Links

• Pathology of the Small and Large Intestines
• Peyer's Patches
• Caecum Revision Flashcards

Videos

• Pot 48 The Small and Large intestine of the Ruminant
• Pot 52 Lateral view of the Abdomen of a young Ruminant
• Lateral View of the Equine Abdomen
• Left Sided topography of the Equine abdomen
• Right sided topography of the Equine Abdomen
• Pot 357 The Feline Abdomen
• Small and Large intestine of the Sheep
• The Porcine Abdomen