Now that the sympathetic contribution is accounted for within the inferior hypogastric plexuses, the parasympathetics can be considered. The pelvic splanchnic nerves represent the sacral contribution of the parasympathetic (craniosacral) outflow of the ANS. The pelvic splanchnic nerves contribute parasympathetic supply for the pelvic viscera, along with the parasympathetic supply to the hindgut, which begins at the distal third of the transverse colon (see abdomen module). Pelvic splanchnic nerves are preganglionic parasympathetic fibers whose cell bodies are located in a small lateral horn of gray matter in spinal cord levels S2, 3, and 4. These preganglionic fibers leave the lateral horn, and subsequently pass through the ventral horn, ventral root, spinal nerve, and ventral ramus associated with S2, 3, and 4. These fibers then directly branch off the ventral rami as pelvic splanchnic nerves and join the inferior hypogastric plexus.
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