A plain-language guide to common spine-related terms often seen in radiology reports (cervical, thoracic, and lumbar spine).
This page explains general imaging terminology only and does not interpret or diagnose individual findings.
What This Page Covers
This page explains commonly used spine terminology such as:• Disc bulge
• Disc protrusion
• Disc extrusion
• Annular fissure / annular tear
• Modic changes (Type 1 / Type 2 / Type 3)
• Spondylosis
• Facet arthropathy
• Canal narrowing
• Foraminal narrowing
• Endplate changes
• Disc desiccationIf your report includes MRI or CT terminology, you may also find context in:
MRI Terms Explained
CT Terms Explained
How Radiologists Describe the Spine
Radiologists describe the shape, height, hydration, and contour of the discs, as well as the appearance of the vertebrae, joints, canals, and nerve exit pathways.These terms document what the images show, not whether a particular finding is clinically important.
Common Spine Terms Explained
Disc BulgeA disc bulge is a broad, smooth extension of disc tissue beyond its usual boundary.
It involves a wide portion of the disc (more than 25% of the circumference).This is a descriptive imaging term and refers only to shape.⸻Disc ProtrusionA protrusion is a more focal extension of disc material.
It involves a smaller, localized portion of the disc compared with a bulge.Again, this term describes contour, not cause or effect.⸻Disc ExtrusionAn extrusion is when disc material extends further beyond the disc space, with a narrower base and a wider extension.
This is a contour-based imaging description.⸻Annular Fissure / Annular TearA radiologist may describe a fissure in the outer layer of the disc (the annulus).
This wording describes structure — not symptoms or interpretation.⸻Disc Desiccation/DehydrationDisc desiccation refers to reduced water content in the disc.
This is often seen as darker signal on MRI.For more MRI terminology, visit:
MRI Terms Explained⸻Modic Changes (Type 1, Type 2, Type 3)These describe changes in the vertebral bone marrow next to the discs:
• Type 1: Edema-like appearance
• Type 2: Fat-like appearance
• Type 3: Sclerotic (dense) appearanceModic types categorize visual characteristics.⸻SpondylosisA broad term describing degenerative changes of the spine, which may include:
• small osteophytes
• mild disc changes
• facet joint changesIt is a general description of appearance.For more general degenerative terminology, see:
Degenerative Joint Terminology Explained⸻Facet ArthropathyThis refers to degenerative changes of the small joints at the back of the spine (facet joints).
It describes shape, contour, and joint space appearance.⸻Canal Narrowing (Spinal Canal)A radiologist may describe narrowing in the central spinal canal.
This refers to the space available for the neural structures seen on imaging.It does not indicate symptoms — only appearance.⸻Foraminal NarrowingThe neural foramina are openings where nerves exit the spine.
Foraminal narrowing describes reduced space in these openings.⸻Endplate ChangesThe vertebral endplates may show:
• irregularity
• sclerosis
• small defectsThese changes are visual observations adjacent to the discs.
Why Radiologists Use Neutral, Descriptive Wording
Radiologists document spine appearance using objective, widely accepted terminology.This ensures:
• clarity
• consistent communication
• accurate comparison over time
• separation of appearance from clinical interpretationThe treating clinician integrates imaging findings with symptoms, examination, and history.For more general terminology, visit:
Radiology Questions Explained
FAQ — Common Questions About Spine Terminology
Does a disc bulge or protrusion indicate how someone feels?Not by itself.
These terms describe the disc’s contour on imaging.⸻What is the difference between a bulge and a protrusion?A bulge is broad-based, while a protrusion is more focal.
Both describe shape only.⸻What do Modic changes mean?Modic types describe the visual appearance of vertebral bone marrow next to the discs.⸻Does foraminal or canal narrowing indicate a specific condition?These terms describe the amount of space visible on imaging.
Clinical relevance is assessed by the treating clinician.⸻What is an annular fissure?A descriptive term for a small structural change in the outer portion of the disc.⸻Where can I learn more about other radiology terms?You can explore:
MRI Terms Explained
CT Terms Explained
Degenerative Joint Terminology Explained
Lesion Terminology Explained
Contrast Agents Explained
If Your Report Mentions Spine Findings and You Want a Clear Explanation
Upload your report and receive a plain-language summary describing what the terminology means in your specific report — without medical advice or diagnosis.✔ Educational explanation
✔ Clear, neutral wording
✔ Private delivery by emailExplain my report → €59