Nerve
Sacral plexus
Lumbosacral fibers gathered on the pelvic surface of piriformis
High-yield
The lumbosacral trunk contributes L4–L5. The sciatic nerve usually contains L4–S3 fibers, whereas the pudendal nerve contains S2–S4.
Overview
The sacral plexus combines the lumbosacral trunk with sacral anterior rami on the posterior pelvic wall. Its major branches carry motor and sensory fibers to the buttock, posterior thigh, leg, foot and perineum.
Reference facts
- Origin
- Anterior rami S1–S4 join the L4–L5 lumbosacral trunk.
- Root value
- Overall L4–S4; superior gluteal L4–S1, inferior gluteal L5–S2, sciatic L4–S3, posterior femoral cutaneous S1–S3 and pudendal S2–S4.
- Course
- Lies anterior to piriformis and behind the internal iliac vessels; major limb branches leave through the greater sciatic foramen.
- Motor
- Supplies gluteal and posterior-thigh muscles, leg and foot muscles, and perineal/pelvic-floor muscles through its branches.
- Sensory
- Serves much of the buttock, posterior thigh, leg and foot, together with perineal and external-genital skin.
Mnemonic
Follow the posterior pelvic wall: piriformis lies behind the plexus, and the sciatic route leads toward the limb.
Clinical correlation
Pelvic trauma, tumors or compression during childbirth can involve multiple branches at once. A plexus lesion may therefore cause weakness and sensory loss spanning more than one peripheral nerve territory.
Frequently asked questions
What are the roots of the sacral plexus?
Overall L4–S4; superior gluteal L4–S1, inferior gluteal L5–S2, sciatic L4–S3, posterior femoral cutaneous S1–S3 and pudendal S2–S4.
What muscles does the sacral plexus supply?
Supplies gluteal and posterior-thigh muscles, leg and foot muscles, and perineal/pelvic-floor muscles through its branches.
What is the sensory distribution of the sacral plexus?
The sacral plexus carries sensation from the serves much of the buttock, posterior thigh, leg and foot, together with perineal and external-genital skin.
What is the course of the sacral plexus?
Lies anterior to piriformis and behind the internal iliac vessels; major limb branches leave through the greater sciatic foramen.