Descending colon lies at the left side of the abdomen in both the upper and lower quadrants. It begins at the left colic flexure and ends by becoming continuous with the sigmoid colon, at the pelvic brim. It is about 10 inches long and is covered from the front and sides by the peritoneum, which binds it to the posterior abdominal wall.
Relations of descending colon:
- Coils of small intestine
- Greater omentum
- Anterior abdominal wall
- Lateral border of left kidney
- Origin of transversus abdominis muscle
- Quadratus lumborum muscle
- Iliac crest
- Iliacus muscle
- Left psoas muscle
- Iliohypogastric and Ilioginuinal nerves
- Lateral cutaneous nerve of thigh
- Femoral nerve
Blood supply of descending colon:
Descending colon is supplied by left colic artery and sigmoid artery, both of which are branches of the inferior mesenteric artery.
The veins correspond to the arteries and drain into the inferior mesenteric vein.
Lymph drainage of descending colon:
The lymph from the descending colon first drains into the colic lymph nodes, from where it eventually drains to the inferior mesenteric lymph nodes, which are situated around the root of inferior mesenteric artery.
Nerve supply to descending colon:
Descending colon receives sympathetic and parasympathetic pelvic splanchnic nerves through the inferior mesenteric plexus.