Lumbar spine
Updates to Article Attributes
The lumbar spine consists of five adjacent vertebrae of the mid-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.
Gross anatomy
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
- 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)
See: fifth lumbar vertebra article for distinctive features of L5.
Articulations
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.
Attachments
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
Relations and/or boundaries
Can be superimposed onto the three-column concept.
Anterior column
- anterior longitudinal ligament: anterior to vertebral body
Middle column
- posterior longitudinal ligament: lies posterior to vertebral body
- centrally
- vertebral foramen
- cauda equina
- basivertebral veins and internal vertebral venous plexus
- laterally
- Iliolumbar ligament
- lumbar fascia
- quadratus lumborum muscle
- intertransverse ligaments
- regional/segmental lumbar arteries and veins
Posterior column
- ligamentum flavum
- interspinous ligament
- supraspinous ligament
- erector spinae muscle
- external vertebral venous plexus (lying within muscle)
Blood supply
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.
Variant anatomy
There are several transitionalTransitional vertebrae of the lumbar spine are possible at multiple levels in the lumbar spine.
Limbus vertebrae represent herniation of the disc nucleous throughpulposus through the superior endplate and can simulate fracturesa fracture.
Development
Transverse processes are actually fused ribs. Mamillary process and the accessory tubercle are the remnants of the true transverse process, typically seen on a thoracic vertebrae
-</ul><h4>Blood supply</h4><p>Arterial supply comes from regional/segmental <a href="/articles/lumbar-arteries">lumbar arteries</a>.</p><p>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.</p><h4>Variant anatomy</h4><p>There are several <a href="/articles/transitional-vertebra">transitional vertebrae</a> of the lumbar spine.</p><p><a title="Limbus vertebra" href="/articles/limbus-vertebra">Limbus vertebrae </a>represent herniation of the disc nucleous through the superior endplate and can simulate fractures.</p><h4>Development</h4><p>Transverse processes are actually fused ribs. Mamillary process and the accessory tubercle are the remnants of the true transverse process, typically seen on a thoracic vertebrae</p>- +</ul><h4>Blood supply</h4><p>Arterial supply comes from regional/segmental <a href="/articles/lumbar-arteries">lumbar arteries</a>.</p><p>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.</p><h4>Variant anatomy</h4><p><a href="/articles/transitional-vertebra">Transitional vertebrae</a> of the lumbar spine are possible at multiple levels in the lumbar spine.</p><p><a href="/articles/limbus-vertebra">Limbus vertebrae</a> represent herniation of the disc nucleous pulposus through the superior endplate and can simulate a fracture.</p><h4>Development</h4><p>Transverse processes are actually fused ribs. Mamillary process and the accessory tubercle are the remnants of the true transverse process, typically seen on a thoracic vertebrae</p>
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