The intervertebral disc

Intervertebral disc anatomy

Intervertebral discs are located in between the vertebrae and play a key role in the spinal mobility and forces' distribution through the spine.

intervertebral disc

Intervertebral discs are composed of two main structures: a fibrous external annulus which contains a gelatinous substance, the nucleus pulposus.

The annulus fibrosus:
It is composed of concentric layers of fibrocartilage (collagen fibers). The arrangement of fibers confers its resistance to the disc.

The nucleus pulposus: 
Mainly composed of water -up to 70-90% depending on the age-, collagen and proteoglycans (type of proteins).
These components confer elasticity and ability to resist compression to the disc.

The disc degeneration

Over time and due to aging, discs tend to dehydrate.

The disc degeneration is a natural aging process in which the disc loses water, becomes rigid, and can collapse, thereby reducing its shock-absorbing capacity. 

Most of the time, the phenomenon is asymptomatic.

Pathologies

Sometimes, the degeneration of the disc can lead to disc diseases (also called discopathies). 
When the disc loses its elasticity and becomes rigid, it can lead to excessive stress on bones or nerves, thus causing pain.

Discopathy can affect any disc, and multiple discs can be affected simultaneously.