Nerve
Pelvic splanchnic nerves
Parasympathetic fibers from the second to fourth sacral segments
High-yield
Pelvic splanchnic nerves are parasympathetic. Sacral splanchnic nerves, despite the similar name, carry sympathetic pathways from the sacral sympathetic trunk.
Overview
Pelvic splanchnic nerves leave the S2–S4 anterior rami and enter pelvic autonomic plexuses. Their fibers influence the hindgut, urinary bladder and erectile tissues, with synapses in ganglia close to or within target organs.
Reference facts
- Origin
- Arise from anterior rami of sacral spinal nerves S2, S3 and S4.
- Root value
- S2–S4.
- Course
- Join the inferior hypogastric plexus and continue through organ-specific plexuses to peripheral ganglia.
- Motor
- Promote hindgut motility, detrusor contraction and the vascular responses involved in erection; bladder emptying requires coordinated outlet relaxation.
- Sensory
- Carry visceral afferents, including pain pathways from structures below the pelvic pain line and reflex information from pelvic organs.
Mnemonic
Pelvic pairs with parasympathetic; sacral splanchnic pairs with sympathetic.
Clinical correlation
Pelvic autonomic pathways lie near the rectum and reproductive organs. Injury in this region can disturb bladder emptying, bowel function or erectile responses.
Frequently asked questions
What are the roots of the pelvic splanchnic nerves?
The pelvic splanchnic nerves arise from S2–S4.
What muscles do the pelvic splanchnic nerves supply?
Promote hindgut motility, detrusor contraction and the vascular responses involved in erection; bladder emptying requires coordinated outlet relaxation.
What is the sensory distribution of the pelvic splanchnic nerves?
Carry visceral afferents, including pain pathways from structures below the pelvic pain line and reflex information from pelvic organs.
What is the course of the pelvic splanchnic nerves?
Join the inferior hypogastric plexus and continue through organ-specific plexuses to peripheral ganglia.