Pelvic Splanchnic Nerves Flashcards

Trace the sacral parasympathetic pathways from S2 to S4, including their pelvic plexus connections, visceral supply, and functions.

Card 1 of 27Question

Which spinal nerve segments give rise to the pelvic splanchnic nerves?

The second, third, and fourth sacral spinal nerve segments (S2 to S4).

In This Section

1. Which spinal nerve segments give rise to the pelvic splanchnic nerves?

The second, third, and fourth sacral spinal nerve segments (S2 to S4).

2. From which parts of the sacral spinal nerves do pelvic splanchnic nerves arise?

The anterior rami of S2, S3, and S4.

3. Which division of the autonomic nervous system do pelvic splanchnic nerves belong to?

The parasympathetic division.

4. What type of autonomic motor fibers do pelvic splanchnic nerves primarily carry?

Preganglionic parasympathetic fibers.

5. Where are the cell bodies of preganglionic pelvic parasympathetic neurons located?

In the sacral parasympathetic nucleus of the spinal cord at S2 to S4.

6. Which major autonomic plexus receives the pelvic splanchnic nerves?

The inferior hypogastric plexus.

7. Where is the inferior hypogastric plexus located?

In the extraperitoneal connective tissue on each side of the pelvic viscera.

8. Where do preganglionic fibers from the pelvic splanchnic nerves typically synapse?

In terminal or intramural parasympathetic ganglia near or within their target organs.

9. Which part of the gastrointestinal tract receives parasympathetic innervation from pelvic splanchnic nerves?

The hindgut, including the distal transverse colon, descending colon, sigmoid colon, and rectum.

10. Which nerve provides parasympathetic innervation to the foregut and midgut instead of the pelvic splanchnic nerves?

The vagus nerve (cranial nerve X).

11. Through which autonomic plexus do pelvic parasympathetic fibers reach the descending and sigmoid colon?

The inferior mesenteric plexus and its periarterial branches.

12. What is the principal effect of pelvic splanchnic nerve stimulation on hindgut motility?

Increased intestinal peristalsis and motility.

13. How do pelvic splanchnic nerves contribute to the defecation reflex?

They stimulate rectal contraction and promote relaxation of the internal anal sphincter.

14. Which muscle of the urinary bladder is stimulated by pelvic splanchnic parasympathetic fibers?

The detrusor muscle.

15. What effect does pelvic parasympathetic activity have on the bladder outlet during urination?

It promotes relaxation of the smooth muscle at the bladder neck and proximal urethra.

16. Which pelvic autonomic plexus distributes parasympathetic fibers to the urinary bladder?

The vesical plexus, a subdivision of the inferior hypogastric plexus.

17. What role do pelvic splanchnic nerves play in the erectile response?

They promote relaxation of erectile tissue smooth muscle and dilation of penile or clitoral arteries.

18. Which autonomic nerves carry parasympathetic fibers from the pelvic plexus to the erectile tissues?

The cavernous nerves.

19. Which neurotransmitter is released by preganglionic fibers of the pelvic splanchnic nerves?

Acetylcholine.

20. Which receptor type receives acetylcholine at pelvic parasympathetic ganglia?

Neuronal nicotinic acetylcholine receptors.

21. How do pelvic splanchnic nerves differ from sacral splanchnic nerves?

Pelvic splanchnic nerves carry parasympathetic outflow, whereas sacral splanchnic nerves carry sympathetic fibers.

22. From which structure do sacral splanchnic nerves arise?

The sacral sympathetic trunks.

23. What type of sensory information commonly travels with pelvic splanchnic nerves?

Visceral afferent information related to organ distension, reflexes, and some pelvic visceral pain.

24. Which surgical procedure can damage pelvic splanchnic pathways during dissection near the rectum?

Total mesorectal excision or other extensive rectal surgery.

25. What urinary dysfunction may result from bilateral injury to pelvic parasympathetic pathways?

Impaired detrusor contraction and urinary retention.

26. What sexual dysfunction may follow injury to pelvic parasympathetic nerves during pelvic surgery?

Impaired penile or clitoral erection.

27. Why are pelvic splanchnic nerves considered part of the craniosacral autonomic outflow?

They originate from sacral spinal cord segments and provide the sacral component of parasympathetic outflow.