A sequestered disk is an disc extrusion that has lost contiguity with the parent disk.

Disc herniation through a weakened subchondral vertebral endplate is an intravertebral disk herniation (ie, Schmorl node).

A lumbar intervertebral disc sequestration derives from the extrusion of disc material within the spinal canal or the contiguous foramina through a laceration that involves two anatomical layers: the annulus fibrosus of the intervertebral disc and the posterior longitudinal ligament (PLL). It is included in the radiological presentation of a lumbar disc herniation in up to 28% of cases ¹⁾.