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L2–L3 Intervertebral Disc

The L2–L3 intervertebral disc is a fibrocartilaginous joint situated between the second and third lumbar vertebral bodies. It is less frequently affected by degenerative changes compared to the lower lumbar discs (L4–L5, L5–S1) but remains clinically relevant in disc pathology, degenerative disease, and trauma.

It plays an important role in load distribution, maintaining spinal flexibility, and stabilizing the upper lumbar spine. Because of its location, disc herniation at this level can compress the L3 nerve root, leading to anterior thigh pain, quadriceps weakness, and reduced patellar reflex.

Synonyms

  • L2–L3 disc

  • Upper lumbar intervertebral disc

  • Lumbar disc at second–third vertebra

Structure

  • Annulus fibrosus: Outer concentric fibrocartilaginous lamellae with low water content, designed to resist tensile and rotational forces.

  • Nucleus pulposus: Central gelatinous core, highly hydrated in youth, gradually losing water content with aging.

  • Cartilaginous endplates: Thin hyaline cartilage layers anchoring the disc to L2 and L3 vertebral bodies, permitting diffusion of nutrients.

Relations

  • Anteriorly: Anterior longitudinal ligament and retroperitoneal tissues

  • Posteriorly: Posterior longitudinal ligament, epidural space, and lumbar spinal canal containing cauda equina roots

  • Laterally: Exiting L2 nerve roots in the neural foramina

  • Superiorly: Inferior endplate of L2 vertebral body

  • Inferiorly: Superior endplate of L3 vertebral body

Function

  • Shock absorption between L2 and L3 vertebral bodies

  • Provides mobility for flexion, extension, and lateral bending of the upper lumbar spine

  • Distributes axial loads and resists shearing forces

  • Maintains structural integrity of the lumbar curvature

Clinical Significance

  • Disc herniation: L2–L3 herniation compresses the L3 root, causing anterior thigh pain, sensory loss, quadriceps weakness, and diminished knee reflex.

  • Degenerative disc disease: Less common here than at lower lumbar levels but may cause chronic mid-lumbar pain.

  • Infection (spondylodiscitis): L2–L3 disc can be involved in tuberculous or pyogenic spondylitis.

  • Trauma: Can be injured in high-energy fractures of lumbar spine.

  • Surgical relevance: Target in decompression or fusion procedures.

MRI Appearance

T1-weighted images:

  • Nucleus pulposus: Low-to-intermediate signal

  • Annulus fibrosus: Low signal intensity ring surrounding nucleus

  • Degeneration: overall low signal intensity of both nucleus and annulus

T2-weighted images:

  • Nucleus pulposus: Normally bright signal (due to high water content)

  • Annulus fibrosus: Dark, low-signal outer ring encasing the nucleus

  • Degeneration: loss of bright signal in nucleus (“dark disc” sign)

  • Annular tears: appear as focal bright lines within the normally dark annulus

STIR (Short Tau Inversion Recovery):

  • Nucleus pulposus: Normally bright signal (due to high water content)

  • Annulus fibrosus: Dark, low-signal outer ring encasing the nucleus

  • Pathology (edema, infection, inflammation): hyperintense signals in disc and adjacent vertebral endplates

T1 Fat-Sat Post-Contrast:

  • Normal disc: minimal or no enhancement

  • Degeneration: annulus may enhance mildly

  • Infection: diffuse disc and endplate enhancement

  • Annular tear: focal peripheral enhancement

CT Appearance

Non-Contrast CT:

  • Disc appears as soft tissue density between vertebral bodies

  • Disc height maintained in normal state

  • Degeneration: disc space narrowing, vacuum phenomenon (gas), or calcification

  • Herniation: focal posterior or lateral protrusion compressing thecal sac or foramina

Post-Contrast CT:

  • Normal disc shows little to no enhancement

  • Infection: diffuse enhancement of disc and adjacent endplates

  • Neoplastic infiltration: irregular, enhancing mass replacing disc and adjacent vertebra

  • Scar tissue (post-op): enhances, while recurrent disc material does not

MRI image

L2–L3 Intervertebral Disc mri anatomy image

CT image

L2–L3 Intervertebral Disc CT sagittal anatomy image-img-00000-00000