The location of disc herniation has an intimate anatomical relation to which nerve root may be affected by the herniated disc.

On the axial plane, the herniation can be classified as:

• central

• subarticular

• foraminal

• extraforaminal

Subarticular herniations are the commonest, they affect the ipsilateral nerve root inferior to the level of the disc. Foraminal and extraforaminal herniations are also common, they affect the ipsilateral nerve root at the same level as the disc. Central herniations are rare, they may affect multiple nerve roots below the level of the disc, including the contralateral nerve roots, such as in a cauda equina syndrome.