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Intervertebral disk of fourth lumbar vertebra: anatomy, location and function

The intervertebral disc between L4 and L5 (the L4–L5 disc), a fibrocartilage pad with a gel-like nucleus pulposus inside a ring-like anulus fibrosus. Absorbs compressive loads, acts as a shock absorber and allows slight movement between vertebrae.

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Highlighted in the model: Intervertebral disk of fourth lumbar vertebra. Click any part to read about it, or switch off “Highlight topic” to see the whole body. 3D data: BodyParts3D, © The Database Center for Life Science, CC BY 4.0; meshes simplified and recoloured. The model is an adult male.

Intervertebral disk of fourth lumbar vertebra at a glance

What it is
The intervertebral disc between L4 and L5 (the L4–L5 disc), a fibrocartilage pad with a gel-like nucleus pulposus inside a ring-like anulus fibrosus.
Location
Between the bodies of L4 and L5, the disc directly below the named vertebra (the L4/L5 disc).
Function
Absorbs compressive loads, acts as a shock absorber and allows slight movement between vertebrae.
Body system
Skeletal · single, midline structure
FMA ID
FMA16036 (Foundational Model of Anatomy)

Key facts

  • It bears some of the highest loads in the spine; L4–L5 and L5–S1 together account for about 90–95% of lumbar disc herniations.
  • The line joining the tops of the iliac crests (supracristal plane) crosses the L4 spinous process or this interspace.
  • Lumbar discs are the thickest in the column and, like the cervical discs, are taller anteriorly, producing the lumbar lordosis.

Clinical relevance

A posterolateral herniation usually compresses the L5 root: weak big-toe extension (extensor hallucis longus) and numbness over the dorsum of the foot, usually with normal reflexes.

Structures next to the intervertebral disk of fourth lumbar vertebra

The nearest named structures in the 3D model, measured from the centre of each part:

References

  1. Foundational Model of Anatomy: Intervertebral disk of fourth lumbar vertebra (FMA16036). EMBL-EBI Ontology Lookup Service.
  2. OpenStax. Anatomy and Physiology 2e, §7.1 Divisions of the Skeletal System. Rice University, 2022.
  3. Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.

Related anatomy

Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.