Anatomy - sacral plexus Flashcards
Where do the nerves forming the sacral plexus converge?
They converge towards the greater sciatic foramen
What components contribute to make the sacral plexus?
- The lumbosacral trunk (L4,5) from the lumbar plexus
2. S1-S5
What does the sacral plexus lie on?
On the posterior pelvis
What does the sacral plexus lie between?
Between piriformis and the pelvic fascia
What does the sacral plexus lie behind?
Behind the internal iliac artery and vein
Where do the superior gluteal artery and vein run relative to the sacral plexus?
Between the lumbosacral trunk and S1
What runs between the second and third sacral nerves?
The inferior gluteal artery and vein
What are the four major groups/areas supplied by the sacral plexus?
- Supply to levator ani
- Major muscular supply
- Minor muscular supply
- Sensory supply
What are the four branches of the sacral plexus that supply levator ani?
- Pelvic splancnic nerves (PSNS S2-4)
- Pudendal nerve (S2-4)
- Muscular branch to levator ani (pelvic surface) S3,4 -> levators ani and ishiococcygeus
- Perineal branch of S4 -> external sphnicter and puborectalis
What branch does the pudendal nerve give off to levator ani, and specifically which part of levator ani does it supply?
The pudendal nerve gives off the inferior rectal nerve which supplies the external sphincter and puborectalis
What are the major muscular supply branches of the sacral plexus?
- Sciatic nerve -> tibial nerve part (anterior divisions of L4-S3) and common peroneal part (posterior divisions of L4-S2)
- Superior and inferior gluteal nerves (L4, S1, L5-S2)
What are the 3 branches of the minor muscular supply from the sacral plexus?
Most enter the buttock inferior to piriformis muscle
- Nerve to quadratus femoris (L4-S1)
- Nerve to Piriformis (S1, S2)
- Nerve to Obturator internus (L5-S2)
What are the branches of the sensory supply arising from the sacral plexus?
- Coccygeal nerve/coccygeal plexus
2. Posterior femoral cutaneous nerve (S1-3)
