Caecum
Caecum
Also known as: cecum, caecum
The caecum is the blind-ended pouch at the start of the large intestine, lying in the right iliac fossa below the ileocaecal junction. The appendix arises from it.
Overview
The caecum is about 6 cm long and about 7.5 cm wide, which makes it the widest part of the large intestine. It lies in the right iliac fossa on the iliacus and psoas muscles. It is usually covered completely by peritoneum but has no mesentery of its own, so it is somewhat mobile. A retrocaecal recess often lies behind it and frequently holds the appendix.
The ileum enters its posteromedial wall at the ileocaecal valve. About 2 cm below this, the three taeniae coli converge at the base of the appendix. Following the anterior taenia (taenia libera) is the classic surgical way to find the appendix.
- Location
Right iliac fossa, below the level of the ileocaecal junction and above the lateral half of the inguinal ligament.
Parts & subdivisions
- Opening of the ileum with its valve-like lips.
- On the posteromedial wall, where the taeniae converge.
Anatomy
- Innervation
Superior mesenteric plexus (vagal parasympathetic; T10–T12 sympathetic).
- Arterial supply
Anterior and posterior caecal arteries, from the ileocolic artery (SMA).
- Venous drainage
Ileocolic vein → superior mesenteric vein.
- Lymphatic drainage
Ileocolic nodes → superior mesenteric nodes.
- Relations
Posterior: iliacus, psoas major, the femoral nerve (deep to fascia) and the lateral cutaneous nerve of the thigh. Anterior: coils of small intestine, greater omentum and the anterior abdominal wall.
Function
- Receives ileal chyme and mixes and stores it.
- Absorbs water and electrolytes.
- Ferments fibre; the proximal colon is the most active fermentation site.
Clinical significance
Caecal carcinoma
The wide lumen and liquid contents mean obstruction occurs late. Patients usually present with occult bleeding and iron-deficiency anaemia, weight loss or a right iliac fossa mass.
Caecal volvulus and perforation
A caecum with an unusually long mesentery can twist, causing obstruction. In distal large-bowel obstruction with a competent ileocaecal valve, the caecum is the usual site of perforation, typically at diameters above about 10–12 cm.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.