Sigmoid Colon

Sigmoid colon is a part of the large intestine of human body. More specifically, it is the continuation of the descending colon into the pelvis. It is about 10-15 inches long and begins where descending colon passes in front of the pelvic brim. Below, it becomes continuous with the rectum at the level of third sacral vertebra.

Sigmoid colon is mobile up to a certain extent. It hangs down into the pelvic cavity in the form of a loop. It is attached to the posterior wall of the pelvis by a fan shaped fold of peritoneum, known as sigmoid mesocolon.

Important relations:

Anterior:

  • Urinary bladder (in males)
  • Posterior surface of uterus and upper part of vagina (in females)

Posterior:

  • Lower coils of terminal part of ileum
  • Rectum
  • Sacrum

Blood supply:

Arterial supply comes from the sigmoid branches of the inferior mesenteric artery. Venous drainage is through the inferior mesenteric vein, which eventually drains into the portal venous system.

Lymph drainage:

The nodes that receive lymph from sigmoid colon lie along the course of the sigmoid arteries. From these nodes, the lymph eventually drains into the inferior mesenteric lymph nodes.

Nerve supply:

Inferior hypogastric plexus supplies both the sympathetic and parasympathetic nerves.