The inferior mesenteric plexus is derived chiefly from the aortic plexus

Aortic plexus

The abdominal aortic plexus is formed by branches derived, on either side, from the celiac plexus and ganglia, and receives filaments from some of the lumbar ganglia....

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It surrounds the inferior mesenteric artery

Inferior mesenteric artery

In human anatomy, the inferior mesenteric artery, often abbreviated as IMA, supplies the large intestine from the left colic flexure to the upper part of the rectum, which includes the descending colon, the sigmoid colon, and part of the rectum...

, and divides into a number of secondary plexuses, which are distributed to all the parts supplied by the artery, viz., the left colic and sigmoid plexuses, which supply the descending and sigmoid parts of the colon

Colon (anatomy)

The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...

; and the superior hemorrhoidal plexus, which supplies the rectum

Rectum

The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

 and joins in the pelvis

Pelvis

In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

 with branches from the pelvic plexuses.