Pyriformis muscle lesions can cause numbness in the feet, and contracture of the pyriformis muscle can lead to pyriformis syndrome. Piriformis syndrome can lead to sciatic nerve damage, which can cause pain and numbness in the lower limbs. The sciatic nerve is responsible for sensation and movement in the feet, so once the pyriformis muscle has become diseased, such as contracture or other inflammatory diseases may lead to numbness in the feet, and the sciatic nerve is the root cause of the numbness symptoms.