
What makes up the spine?

The spine has four main components: bones, discs, nerves and ligaments.
The bones of the spine or vertebrae are the main structural supporting body. Calcium rich, these bones are the strong matrix providing for protection of what lies beneath, or within the spine, the nerves. With openings centrally, the canal and to the side, foramen, the nerves can pass from the control centers of the brain and spinal cord to the action centers of the muscle and skin. These are very strong and protective, but also quite rigid. To encase the nerves for maximal protection, these vertebral bones form a ring around them.
Stacked one on top of another, these vertebrae twist and bend based on what rests between them, discs. These cartilaginous, soft and spongy structures allow for separation of the bones and with their elasticity, provide for the spines ability to flex or angle, allowing for greater functionality. The outer disc or annulus fibrosus is the strongest layer and rests on the perimeter, closest to the nerves. Inside of this annulus is the nucleus pulposus. This gel-like material is less rigid, in fact soft in nature, allowing for even more in the way of flexibility and impact or shock absorption.
The nerves are central to and encased within the bones, and adjacent to the discs. Starting from the brain, the nerves traverse the stacked vertebrae, top to bottom, some pairs exiting at each subsequent layer down.
The ligaments are tough cartilage strands that lie along the sides or are intertwined amongst bones and discs of the spine.
Muscles of varied lengths, while technically outside of the spine proper provide beams, or columns of support for all of the above structures