The spine is located in the middle of the back, the central axis of the trunk, and consists of 33 vertebrae. Of these, 7 are cervical, 12 are thoracic, 5 are lumbar, 5 are sacral, and 4 are caudal. 5 sacral vertebrae are fused into one block called the sacrum, and 4 caudal vertebrae are fused into one block called the coccyx. Each of these vertebrae has a hole in the center that connects to the spinal canal, which is the part that houses the spinal cord and protects it. Each vertebra has an articulation with an adjacent vertebra, called the intervertebral joint. The adjacent vertebrae are connected by fibrocartilaginous discs called intervertebral discs. The human vertebrae are connected as a whole by the intervertebral joints, intervertebral discs, and surrounding ligaments. When the spine is observed from the front or back, the vertebrae gradually increase from top to bottom, and the spine is basically straight with a slight scoliosis of 10° or less. For example, in a person who is habitually right-handed, the upper part of the spine is slightly convex to the right, and the lower part is compensatingly slightly convex to the left. The spine is slightly curved in an “S” shape when viewed from the side. It consists of four physiological curves: cervical, thoracic, lumbar, and sacral. The cervical and lumbar curvatures are convex forward, while the thoracic and sacral curvatures are convex backward, and their curvatures are related to maintaining the body’s center of gravity. Changes in these physiological curvatures are bound to change the body’s center of gravity and disrupt the balance of the trunk, resulting in pain in the spine. In addition to supporting the body and protecting the spinal cord, the spine has a motor function. In the neck, the joint surface of the cervical spine is an inclined planar joint with thick intervertebral discs, so it can do flexion, extension, lateral flexion, rotation and rotation, and the range of motion is larger. The thoracic spine is connected to the rib cage, and its intervertebral discs are thin, and the direction of the joint surface is not suitable for rotational and flexion-extension movements, so the mobility of the thoracic spine is very small, especially in the mid-thoracic region where the range of motion is even smaller. In the lumbar region, because of the thick intervertebral disc, more flexible movements can be made, but because of the special shape of its joints, rotational movements are somewhat restricted and not as flexible as those of the cervical spine. Because of the more flexible movements of the cervical and lumbar regions, spinal injuries are mostly seen in the cervical and lumbar regions.