In a patient with sciatic nerve damage, what motor deficits might be observed?
Answer:
Weak hip extension, loss of knee flexion, and loss of ankle and foot movements.
Explanation:
The sciatic nerve (L4–S3) is the major motor nerve of the lower limb and divides into the tibial and common fibular (peroneal) nerves.
Weak hip extension: The hamstrings, supplied by the sciatic nerve, assist with hip extension. However, hip extension is not completely lost because the main hip extensor, gluteus maximus, is supplied by the inferior gluteal nerve.
Loss of knee flexion: The hamstrings, mainly supplied by the tibial division, flex the knee.
Loss of ankle and foot movements: The tibial and common fibular divisions supply essentially all muscles below the knee, so injury can cause marked loss of dorsiflexion, plantarflexion, inversion, eversion, and toe movements.
