Lumbar spine

Dr Craig Hacking and Dr Aaron Wong et al.

The lumbar spine consists of five adjacent vertebrae of the lower vertebral column. They participate in the lumbar lordosis, a natural curve in the spine, that is convex anteriorly. 

Articulations of the facet (zygapophyseal) joints permit flexion/extension and abduction movements. Rotation is greatly limited, and may occur only slightly at the lumbosacral joints.

For a basic anatomic description of the structure a generic vertebra, see vertebrae.

Similar to other vertebrae, the osteology of each lumbar vertebrae can be subdivided anteriorly to posteriorly:

  • body: kidney shaped, convex anteriorly, flattened posteriorly; resulting vertebral canal is triangular in cross-section
  • pedicles: project directly posteriorly, attached to the upper half of the body
  • transverse processes: spatulate, project laterally on both sides; L3 most often has the longest transverse processes of the lumbar spine, a fact that can be used to number the vertebrae
  • lamina: broad, thick, overlap minimally
  • articular processes (superior and inferior): lie at the lateral angle of the laminae (junction with pedicle), connected via the pars interarticularis
  • spinous process: single, short, thick, roughly horizontal, hatchet-shaped (upper border is straight, lower border curves down)

L1 to L4 are considered typical lumbar vertebrae, whereas due to various and distinctive differences the fifth lumbar vertebra is considered atypical.

Vertebrae articulate with one another via:

  • intervertebral discs (superior and inferior): wedge shaped (taller anterior, shorter posterior), and contribute most to the lumbar lordosis
  • facet (zygapophyseal) joints: obliquely oriented, cylindrically-shaped articular surfaces
    • superior articular facets are concave and face posteromedially
    • inferior articular facets are convex, and face anteriorly

Inferior articular process of the vertebrae above always lies posterior to the superior articular process of the vertebrae below.

A large number of attachments occur at the transverse process. On its anterior surface, a vertical ridge serves as an important landmark.

  • medial to ridge: psoas muscle
  • at the ridge: psoas fascia, anterior layer of the lumbar fascia, medial and lateral arcuate ligaments (at L1)
  • lateral to ridge: quadratus lumborum partially inserts
  • transverse process tip: middle layer of lumbar fascia

Posterior surface receives attachments of erector spinae. Back muscles (multifidus, longissimus) attach to the mamillary process and accessory tubercle:

  • mamillary process: located on the superior articular process, behind the margin of the articular facet, projects posteriorly
  • accessory tubercle: located at the root of the transverse process, projects posteriorly

Can be superimposed onto the three-column concept.

Arterial supply comes from regional/segmental lumbar arteries.

Venous drainage is complex. Lumbar vertebral bodies are posteriorly perforated by a pair of basivertebral veins that drain into the internal vertebral venous plexus. Regional/segmental lumbar veins also contribute.

Transitional vertebrae of the lumbar spine are possible at multiple levels in the lumbar spine.

Limbus vertebrae represent herniation of the disc nucleous pulposus through the superior endplate and can simulate a fracture.

Transverse processes are actually fused ribs. Mamillary process and the accessory tubercle are the remnants of the true transverse process, typically seen on thoracic vertebrae.

Anatomy: Abdominopelvic
Anatomy: Spine
Share article

Article information

rID: 33183
Section: Anatomy
Tag: refs
Synonyms or Alternate Spellings:
  • Typical lumbar vertebrae
  • Lumbar vertebrae

Support Radiopaedia and see fewer ads

Cases and figures

  • Figure 1
    Drag here to reorder.
  • Figure 2: superior view
    Drag here to reorder.
  • Figure 3: lateral view
    Drag here to reorder.
  • Figure 4: annotated oblique projection
    Drag here to reorder.
  • Case 1: MRI normal lumbar spine
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.