Slipped disc

Prolapsed intervertebral disc is a condition where the gelatinous nucleus pulposus squeezes through the annulus fibrosus and bulges in a posterior or posterolateral direction, beneath the posterior longitudinal ligament:

• this causes pressure symptoms on the root below the level of herniation - most commonly S1, then L5, then L4.
• other defects are rarer, and higher defects ought to be investigated for other causes

Reference

1. Dydyk A. et al. Disc Herniation. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.