The intervertebral disc is composed by a central compartment (pulpy nucleus) and by an external one (fibrous anulus).
The anulus is constituted by an internal portion with an indistinct limit with the pulpy nucleus and by an external one whose fibres constitute the fibres of Sharpei. These fibres form a crown that, being thicker at the front, assures a considerable resistance to the forces of tractions.
Degenerative Discopathy: with this term or other synonyms, as discoarthrosis or disk bulging or common disk protrusion, we mean a prominence of the fibrous anulus, extended to the whole circumference, that takes place starting from a dehydration of the pulpy nucleus that causes a decrease in the height of the disc;
Disk protusion: with this term we define a local prominence (focal) in the profile of a disc, struck by degenerative phenomena, that has formed because of the collapse without the breaking of the fibres that contain it;
Herniated disk: with this term we mean a discharge of the material of the pulpy nucleus of the disc. It is caused by the breaking of the fibres of the fibrous anulus that form the wall of the disc itself.