Where is the sciatic nerve?
Formed by the L4 to S3 nerve roots, it leaves the pelvis below the piriformis muscle, runs down the back of the thigh and divides above the knee into the tibial and common fibular nerves.
What does the sciatic nerve do?
Moves the hamstrings and every muscle below the knee and gives sensation to most of the leg and foot.
Clinical relevance of the sciatic nerve
- Sciatica is pain that radiates from the buttock down the back of the leg, usually from a herniated lumbar disk pressing on a nerve root.
- Intramuscular injections in the dorsogluteal site can injure the sciatic nerve, which is why the ventrogluteal site is preferred.
- Pressure on the common fibular nerve at the head of the fibula (tight cast, crossed legs, stirrups) causes foot drop.
Nursing focus: the sciatic nerve
- Use the ventrogluteal site for gluteal intramuscular injections.
- With a leg cast, check sensation on top of the foot and the ability to lift the toes, and pad the fibular head.