sigmoid colon

The sigmoid colon is the continuation of the descending colon.

Gross anatomy

After the distal descending colon has curved medially it enters the pelvis, where it gains a mesentery and is then called the sigmoid colon. It measures approximately 15 cm in length.

It has a "S" (Greek letter sigma) shape and has a variable length and course - its apex may be as high as the umbilicus. It lies on its own mesentery - the inverted V-shaped sigmoid mesocolon.

The sigmoid colon continues as the rectum when it loses its mesentery, at approximately S3.

Relations

Blood supply

Nerve supply

  • sympathetic: inferior mesenteric plexus 
  • parasympathetic: via pelvic splanchnic nerves (from S2-S4)

Lymphatic drainage

Lymphatics travel with vessels to the inferior mesenteric group.

Related pathology