Disc Bulge
· A broad-based, symmetrical extension of the disc beyond its normal boundaries.
· Involves more than 25% of the disc circumference.
· The annulus fibrosus (outer layer) remains intact, but weakened or stretched.
· Often part of degenerative disc disease.
· May not compress nerves unless severe.
🧠 Think of a slightly overinflated tire bulging evenly all around.
Disc Herniation
This is a focal displacement of disc material beyond the intervertebral disc space, usually involving less than 25% of the disc circumference.
There are three main types:
1. Protrusion
· Disc material pushes out, but the base is wider than the dome.
· Annulus is disrupted but still contains the nucleus pulposus (inner gel).
· Focal, but contained herniation.
🧠 Like a bubble pushing through wallpaper—still attached and contained.
2. Extrusion
· Disc material escapes through a tear in the annulus, and the tip is wider than the base.
· The nucleus pulposus leaks out of the disc space.
· More severe and more likely to compress nerves.
🧠 Like squeezing toothpaste—some spills out through a narrow hole.
3. Sequestration (Sequestered Disc)
· A free fragment of disc material has broken off and is completely separated from the parent disc.
· May migrate up or down the spinal canal.
· Can cause severe nerve root compression or inflammation.
🧠 Like a piece of broken jelly floating away from its container.
Summary Table:
| Term | Shape/Extent | Annulus Intact? | Nucleus Leaked? | Risk to Nerves |
| Bulge | Broad, >25% of disc | Yes | No | Low (unless severe) |
| Protrusion | Focal, base wider than tip | Partially | No | Moderate |
| Extrusion | Focal, tip wider than base | No | Yes | High |
| Sequestration | Free fragment | No | Yes | Very high |
