BoneIrregular bone

Lumbar vertebra L5

Latin: Vertebra lumbalis V

Location: Lower back — lumbosacral junction

View the lumbar vertebra l5 in 3D

Function

Sits like a keystone at the lumbosacral angle, transferring the whole upper-body load onto the sacrum. The L5 root supplies the gluteus medius, toe extensors and lateral leg skin.

Landmarks

  • Wedge-shaped body
  • Thick transverse processes
  • Lumbosacral angle

Articulations (joints)

  • L4 above
  • Sacrum (lumbosacral joint)

Clinical relevance

Spondylolisthesis — L5 slipping forward on the sacrum — is common here; L5–S1 disc herniation presses the S1 root, killing the ankle jerk.

Related conditions

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