The spinal cord is the channel connecting the brain and the body. After the brain sends a signal, it transmits the signal to all parts of the body through the spinal cord nerve to control the feeling and movement of the limbs of the body. The spinal cord is located in the spinal canal, and its upper end is connected with the medulla oblongata of the brain. In the spinal canal, it sends out pairs of nerve bundles through the intervertebral foramen on both sides, which are distributed throughout the body and limbs to control the feeling and muscle movement of the body and limbs.
When the spinal cord reaches the first lumbar plane, it forms a spinal cord cone, and downward will form a cauda equina like nerve bundle, which is called cauda equina nerve. The hot and cold pain felt everywhere in the body is transmitted to the brain through the spinal cord for expression. If the spinal cord is compressed or injured, below the injury level, the limbs will have corresponding symptoms, such as limb paralysis, numbness, difficult defecation and so on.