The spinal column (Fig.1) is comprised of boney structures called vertebrae .There are seven cervical (neck), twelve thoracic (chest), five lumbar (low back) and five fused sacral (pelvic) vertebrae. The vertebra act to provide protection of the spinal cord, attachment points for muscles, ligaments, tendons and structural support for the head, shoulders and chest.
Most of the vertebrae of the spine are cushioned with structures called intervertebral discs (Fig.2). The intervertebral discs are gel filled fibrocartilaginous materials that act as shock absorbers.
The rib cage (Fig.3) is attached to the thoracic vertebrae from T-1 to T-10. The ribs at levels 11 and 12 do not attach. The ribs serve as protection for the internal organs.
Articular Hyaline Cartilage
In addition to the discs the surfaces of the vertebrae and the facets are covered with the same articular hyaline cartilage found in all the moveable joints found in the body. This material helps to dissipate the effects of loading and provides a smooth surface for movement with limited friction.