GLOSSARY

The caecum is a blind-ended pouch about 6 centimetres long and the first part of the large intestine, lying in the right iliac fossa (right lower quadrant) below where the ileum enters; the appendix hangs from its posteromedial wall.

Characteristics

• Ileocaecal valve: lets ileal contents into the caecum and prevents backflow.
• The widest part of the large intestine (about 7–8 centimetres), with a thinner wall.
• Intraperitoneal and somewhat mobile.
• Contents: still liquid; bacterial fermentation begins here.

Evolutionary Comparison

In herbivores (such as the horse and rabbit) the caecum is very large and the main site of cellulose fermentation; in humans it is small.

Clinical Application