Numbness in one foot is mainly caused by nerve compression in the foot. First, see the lumbar disc protrusion, especially after the lumbar disc protrusion compression of one side of the nerve root, will cause obvious numbness of the foot, and this numbness only in one side of the foot. Second, see the lower extremity of one side of the sciatic nerve compression, or the common peroneal nerve, tibial nerve compression and cause numbness of the foot. Because the sensation of the foot is innervated by the sciatic nerve, if there is compression of the sciatic nerve in the hip, or compression of the tibial or common peroneal nerve in the popliteal fossa, it will cause obvious numbness of the foot, and after the compression of the tibial nerve, there is numbness of the bottom of the foot, while the compression of the common peroneal nerve is numbness of the back of the foot.