The five largest vertebrae, which carry the weight of the upper body in the small of the back
Lumbar vertebrae — L1 to L5.
Anatomy · Bones
Lumbar vertebra
Five vertebrae, L1 to L5
Spine · lower back
The five lumbar vertebrae, L1 to L5, form the lower back between the thoracic vertebrae and the sacrum. They are the largest, thickest vertebrae in the spine because they bear the weight of the upper body. Their bodies are kidney-shaped, they have no rib facets or transverse foramina, and their short blunt spinous processes point straight back.
How to spot them
- ▸Very large, thick, kidney-shaped vertebral bodies, the biggest in the column
- ▸Short, thick, blunt spinous processes projecting straight backward, like a hatchet
- ▸No costal facets (unlike thoracic vertebrae) and no transverse foramina (unlike cervical vertebrae)
- ▸Triangular vertebral foramen, larger than the thoracic one
What to know
Vertebrae with big kidney-shaped bodies and short, broad, backward-pointing spines, lacking both rib facets and holes in the transverse processes
Lumbar vertebrae — no costal facets and no transverse foramina.
A needle can be passed between their spines into the spinal canal for epidural anaesthesia or to sample cerebrospinal fluid, unlike between the long overlapping spines above
Lumbar vertebrae — used for lumbar puncture and epidural.
On an oblique X-ray, a 'Scottie dog' appearance is seen; a break in its neck indicates a defect of the pars interarticularis
Lumbar vertebra — the Scottie dog sign of spondylolysis.
Slipping forward of one of these vertebrae on the one below, most commonly the fifth over the sacrum, is called spondylolisthesis
Lumbar vertebrae — L5 on S1 is the classic site.
The curve of the spine that develops after birth as a child learns to stand and walk, concave at the back, is found in this region
Lumbar vertebrae — the secondary lumbar curve (lordosis).
Key ideas
- Each vertebra has a body, a vertebral arch, and mamillary and accessory processes; the facet joints face medially and laterally, favouring flexion and extension but limiting rotation.
Quick-fire facts
- •There are five lumbar vertebrae in most people, though six or four occur as variants
- •They are the largest vertebrae because they support the weight of the body when standing
- •The lumbar spine is the site for lumbar puncture, usually below the level where the spinal cord ends
- •Lumbarization is when S1 looks like a sixth lumbar vertebra; sacralization is when L5 fuses to the sacrum
- •The vertebral bodies are kidney-shaped and thicker in front than behind, contributing to lumbar lordosis
- •The spinous processes do not extend below the level of the vertebral body, which allows needle access
- •In the lumbar spine the vertebral foramen is triangular, smaller than in the cervical spine and larger than in the thoracic
- •Lumbar transverse processes are long and slender, and carry a small accessory process on the back
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Sources
- Kenhub — Lumbar vertebrae: anatomy of the bony lumbar spine
- TeachMeAnatomy — The Vertebral Column
- OpenStax — Anatomy and Physiology 2e, 7.3 The Vertebral Column