The composition of the trunk bone mainly includes the cervical vertebrae, thoracic vertebrae, ribs, and sternum, as well as lumbar vertebrae, sacral vertebrae, and coccygeal vertebrae, which together form the complete trunk bone. The cervical spine has 7 vertebrae, of which the 1st cervical vertebra has no vertebral body, just a ring-shaped bone, the 7th cervical vertebral body has a longer posterior protrusion, which is the body surface localization mark of the human vertebrae. Thoracic vertebrae have 12 cones, each thoracic vertebrae are connected with ribs after the ribs, 12 ribs left and right, and the thoracic vertebrae, the sternum together to enclose the thorax, the sternum is divided into the head of the sternum, the sternal handle, the sternum tail of the 3 parts. The lumbar spine has 5 vertebrae, and the intervertebral discs between the lumbar vertebrae are larger, playing the role of lining and cushioning, decompression. The sacral vertebrae are divided into the 1st sacral vertebrae, 2nd sacral vertebrae, 3rd sacral vertebrae and 4th sacral vertebrae in early childhood, and then fused into one whole sacral vertebrae after adulthood, and the caudal vertebrae are composed of the 1st caudal vertebrae, 2nd caudal vertebrae and 3rd caudal vertebrae.