Trunk (thorax, abdomen, back)
Lumbar vertebrae (L1–L5)
Vertebrae lumbales (L1–L5)
- Origin
- 5 massive lumbar vertebrae with large reniform bodies; articulate with T12 and sacrum (L5-S1 lumbosacral junction)
- Insertion
- Attachment site for psoas major, quadratus lumborum, erector spinae, and thoracolumbar fascia
- Function
- Bears the entire weight of the upper torso and head; transmits compressive loads to the pelvis
- Innervation
- Lumbar spinal nerves (L1–L5)
- Movement & chain
- Significant flexion and extension; lateral bending; axial rotation is heavily restricted by sagittal facet joints
- Palpation
- Spacious horizontal spinous processes easily palpable in lumbar lordosis (L4 at iliac crest level)
- Clinical
- Lumbar disc herniation (L4-L5, L5-S1 sciatica); spondylolisthesis; lumbar spinal stenosis (neurogenic claudication); lower back pain
- Segmental innervation
- L1–L5
- In clinical practice
- Primary landmark for lumbar puncture and spinal/epidural anesthesia (L3-L4 or L4-L5 intervertebral space)
- Region in the model
- Trunk (thorax, abdomen, back)