Intervertebral disc

The intervertebral discs (intervertebral fibrocartilages) are interposed between the adjacent surfaces of the bodies of the vertebræ, from the axis to the caudal vertebrae, and form the chief bonds of connection between the vertebræ.

They vary in shape, size, and thickness, in different parts of the vertebral column, the thickness decreasing through the thoracic and lumbar region.

Each intervertebral disc consist of two parts:

• The nucleus pulposus, located at the center of the disc is composed by a soft, pulpy, highly elastic substance, of a yellowish color, that is the remains of the notochord. It is soft but non compressible, so susceptible to herniate inside the vertebral canal.
• The fibrous ring (anulus fibrosus), located at the periphery of the disc, is composed by laminæ of fibrous tissue and fibrocartilage,