Opens in a new tab
Home › Body Atlas › Bones › L1 Vertebra
Bone Lower Back

L1 Vertebra

vertebra lumbalis I

L1 is the first lumbar vertebra at the thoracolumbar junction, the most common level for burst fractures from axial loading injury. The conus medullaris typically terminates at the L1-L2 level in adults. L1 has no costal facets and its transverse processes are vestigial costal elements (costal processes) rather than true transverse processes.

Anatomical Data

Structure & Landmarks

Articulations
  • T12 above
  • L2 below
  • Bilateral facet joints
Landmarks
OssificationThree primary centres fusing by age 6, ring apophyses by age 25.
Clinical Relevance

Clinical Notes

L1 burst fractures are the most common thoracolumbar fractures, occurring from axial load with flexion in falls from height and motor vehicle accidents. The thoracolumbar junction is biomechanically vulnerable due to the transition from the rigid thoracic cage to the mobile lumbar spine. Injury to the conus medullaris at L1 produces a mixed upper and lower motor neuron picture. Neurologically intact burst fractures with less than 50% canal compromise may be managed conservatively. Surgical stabilisation with pedicle screws spanning the fracture level restores alignment.

Pathology

Common Injuries & Conditions

L1 Burst Fracture

L1 is the most commonly fractured vertebra; burst fractures here can injure the conus medullaris and cause bladder, bowel, and lower limb dysfunction.

Osteoporotic Compression Fracture

Anterior wedge collapse of L1 after minor trauma is common in older adults with osteoporosis.

This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.

Accept All Accept Required Only