Nerve
Sciatic nerve
Largest nerve in the body
High-yield
Exits below piriformis via the greater sciatic foramen; divides into tibial and common fibular nerves in the distal thigh.
Overview
The largest nerve in the body, arising from the sacral plexus, supplying the hamstrings and (via its terminal branches) all muscles below the knee.
Reference facts
- Roots
L4, L5, S1, S2, S3 (sacral plexus)
- Course
Leaves the pelvis through the greater sciatic foramen inferior to piriformis, descends deep to the hamstrings, and divides into the tibial and common fibular nerves proximal to the popliteal fossa
- Motor
Hamstrings and the hamstring part of adductor magnus (directly); all leg and foot muscles via its terminal branches
- Sensory
Most of the leg and foot (via terminal branches); no direct cutaneous branches in the thigh
Clinical correlation
Injured by posterior hip dislocation or an incorrectly placed gluteal injection (use the superolateral quadrant).