Caecum and Appendix

Definition

The caecum and appendix are the beginning parts of the large intestine, also known as the colon.

Morphology of Caecum

• The caecum is a pouch-like structure which is approximately 6-9 cm in length and 3-4 cm in diameter.
• It is located at the junction of the small intestine and the large intestine.
• The caecum is attached to the posterior abdominal wall by the meso-caecum.

Morphology of Vermiform Appendix

• The vermiform appendix is a narrow tube approximately 5-12 cm long and 0.5-1.5 cm in diameter.
• It is attached to the caecum at a point about 1-2 cm from the junction of the small intestine and the large intestine.
• The appendix has a meso-appendix which is a fold of peritoneum that attaches the appendix to the caecum.

Relations

• The caecum is related to the ascending colon medially, the ileum laterally and the peritoneum anteriorly.
• The appendix is related to the caecum medially, the ileum laterally and the peritoneum anteriorly.

Blood Supply

• The caecum and appendix are supplied by the ileocolic artery which is a branch of the superior mesenteric artery.
• The ileocolic artery divides into the caecal artery which supplies the caecum and the appendicular artery which supplies the appendix.

Nerve Supply

• The caecum and appendix are supplied by the superior mesenteric plexus which is a part of the sympathetic nervous system.
• The superior mesenteric plexus is formed by the fusion of the sympathetic and parasympathetic nerves.

Applied Anatomy

• During surgery, the caecum and appendix are exposed through an incision in the right iliac fossa.
• The caecum and appendix are removed during an appendicectomy, a surgical procedure to remove the appendix.
• The caecum and appendix are also visible during a barium meal, a radiographic examination of the gastrointestinal tract.

Developmental Process

• The caecum and appendix develop from the midgut which is one of the three parts of the embryonic gut.
• The midgut is formed during the 3rd to 5th week of embryonic development and it gives rise to the caecum, appendix, ascending colon and part of the transverse colon.
• The midgut rotates 90 degrees counterclockwise around the superior mesenteric artery and this rotation causes the caecum to move from the left to the right.