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Lumbrosacral Plexus

- See: Lumbar Plexus:

- Anatomy:
    - lumbosacral plexus is derived from L4, L5, S1, S2, S3 & S4 roots, each giving rise to anterior and posterior branches;
    - anterior branches supply flexor muscles of limb, & posterior branches supply extensor and abductor muscles;
    - superior gluteal nerve (L4  & L5) supplies glutei medius and minimus & tensor fasciae latae;
    - inferior gluteal nerve  (L5, S1, S2) supplies maximus;
    - small nerves derived from L4, L5, S1, S2, S3 supply lateral rotators of thigh except for obturator externus, which is supplied 
            by obturator nerve;
    - sciatic nerve
            - largest derivative of lumbosacral plexus is sciatic nerve, which supplies muscles of posterior thigh & all of muscles of leg and foot;
    - pudendal nerve arises from the ventral rami of S2-S4;

- Injury of Lumbrosacral Plexus:
    - w/ pelvic ring trauma, the nerve which is most often injured is the L4-L5 portions of the lumbral sacral trunk;
    - L4-L5 portion of trunk crosses anterior to sacral ala & sacral iliac joint;
    - it exits the sciatic notch above the piriformis, where is branches off superior gluteal nerve and forms part of sciatic nerve

Anomalies of the lumbosacral nerve roots. An anatomic investigation.

Lumbosacral nerve-root anomalies.