There are three main causes of numbness in the left palm: first, carpal tunnel syndrome, the carpal tunnel area to form more inflammatory hyperplasia, will produce squeezing force on the entire carpal tunnel, resulting in the compression of the median nerve from the inside of the nerve is squeezed nerve fiber ischemia, resulting in the palm of the hand, especially the radial side of the three and a half fingers appear obvious symptoms of numbness. Second, ulnar canal syndrome, because the ulnar nerve travels through the channel with more fiber growth, stimulating the ulnar nerve to appear numbness in one and a half fingers on the ulnar side of the palm. Third, neurogenic cervical spondylosis, due to a herniated disc in the cervical spine, nerve root canal stenosis or intervertebral foraminal stenosis, extrusion and stimulation of the nerve root, resulting in nerve root ischemia, may also lead to numbness in the left palm area.