The Body Axis
The skull and spinal column, taken together, constitute the bony axis of the body, the center of organization of the skeleton; to these parts are attached other skeletal structures, mandible, ribs and sternum, extremities, classified as the appendicular portion of the skeleton. Likewise are attached, directly or indirectly, the voluntary muscles which move the skeleton, and the vessels and viscera. Any given structure in the body can be traced to a supporting connection with this bony axis.
The bony axis contains the neural axis. Its strength and solidity are such as to preserve the integrity of the most vitally important tissue of the body from every form of injury if such protection be possible. Through openings in the bony axis—foramina—the central nerve organs give off or receive the nerve bundles which bring them into communication with every other structure of the body. And the body has been so arranged that every single part of it is partly or wholly under control of nerves emerging through these foramina. Even the brain and spinal cord themselves respond to changes in the blood-vessels which are controlled by nerve impulses which have emerged through the intervertebral or cranial foramina and returned by other routes to supply the muscular coats of the vessels.