Lumbosacral Plexus - Advanced
Inferior gluteal nerve (L5 – S2)
- Innervates gluteus maximus, which provides provides hip extension.
Superior gluteal nerve (L4 – S1)
- Innervates gluteus medius, gluteus minimus, and tensor fasciae latae; all of which provide hip abduction – tensor fasciae latae does when the hip is in flexion.
Iliohypogastric and ilioinguinal nerves (L1).
- Both nerves provide motor innervation to the internal oblique and transversus abdominis muscles.
- Iliohypogastric nerve provides sensory coverage to the suprapubic and upper-lateral gluteal areas.
- Ilioinguinal nerve provides sensory coverage to the superior-medial portion of the thigh and proximal external genitalia.
Genitofemoral nerve (L1–L2)
- Genital branch innervates the cremaster muscle.
- Provides sensory coverage to the scrotum or labia.
- Femoral branch is purely sensory.
- Provides sensory coverage to the femoral triangle.
Lateral cutaneous nerve of the thigh (aka lateral femoral cutaneous nerve) (L2 and L3)
- Provides sensory coverage to the lateral thigh.
Posterior cutaneous nerve of the thigh (aka the posterior femoral cutaneous nerve) (S1 – S3)
- Provides sensory coverage to the midline back of the thigh.
Pudendal nerve (S4 + S2 and S3)
- Branches into the inferior rectal nerve, perineal nerve, and dorsal nerve to the penis or clitoris.
- Provides motor innervation to the external urethral and anal sphincters and external genitalia and it provides sensory coverage to the anus and external genitalia.
Short rotators of the hip (L5 – S2)
- Provide external rotation of the hip when it is in extension and hip abduction when it is in flexion.
- The nerve to quadratus femoris innervates quadratus femoris and gemellus inferior; the nerve to obturator internus innervates obturator internus and gemellus superior; the nerve to piriformis innervates piriformis; and the obturator nerve innervates obturator externus (note that obturator externus is supplied by L3, L4).