BoneIrregular bone

Lumbar vertebra L1

Latin: Vertebra lumbalis I

Location: Lower back — lumbar spine

View the lumbar vertebra l1 in 3D

Function

The top of the lumbar lordosis and the cord's finishing line: below L1 the canal holds the cauda equina — a bundle of nerve roots floating in CSF, which is why lumbar punctures are safe at L3–4.

Landmarks

  • Kidney-bean body
  • Transverse processes
  • Mammillary processes
  • Spinal cord ends (conus medullaris) at this level

Articulations (joints)

  • T12 above
  • L2 below
  • Twelfth rib (variable)

Clinical relevance

The L1 dermatome drapes the groin; burst fractures of L1 damage the conus and cause saddle anaesthesia with urinary retention.

Related conditions

Educational anatomy reference, not medical advice. About this content.