Learning Modules - Medical Gross Anatomy
Autonomics of the Abdomen - Page 7 of 16

The pelvic splanchnic nerves are the only splanchnic nerves that are parasympathetic. They are preganglionic parasympathetic fibers that arise from the lateral horn of the spinal cord at the S2, S3, & S4 levels. They pass from the ventral primary rami of S2, S3, and S4 into the inferior hypogastric plexus, located laterally on the rectum. From there, some fibers pass upward over the left pelvic brim, through the fusion fascia on the posterior abdominal wall, to reach the distal third of the transverse colon, descending colon, and sigmoid colon. These presynaptic fibers synapse in the colon wall on postsynaptic neurons that innervate the gut smooth muscle to cause peristalsis in the hindgut.

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