Lumbar vertebrae

The five lumbar vertebrae are characterised by:

• body:
  • deeper, broader and stronger than in superior vertebrae
  • kidney-shaped from superior aspect
  • no articular costal facets on lateral margins
• vertebral foramen:
  • triangular
  • larger than thoracic foramina, smaller than cervical foramina
• transverse process:
  • base is termed the lateral tubercle
  • a small tubercle, the accessory process, projects posteriorly from lateral tubercle
  • with progression down spine, sequential transverse processes become displaced anteriorly from a junction with only pedicle to junction with only body
  • project posterolaterally
  • increase in length to L3 and then decrease again
• superior articulating process:
  • project vertically up from the pedicle-lamina junction
  • plane of surface directed posteromedially
  • articulating surface concave
  • at posterolateral edge is rounded mamillary process
• inferior articulating surface:
  • at junction of lamina and pedicle projecting vertically
  • articulating surface is convex
  • plane of articulating surface faces anterolaterally
  • with sequential vertebrae down spine, on individual vertebrae, the superior and inferior articulating surfaces get relatively closer together vertically, while inferior articulating processes get further apart horizontally
• spinous process:
  • projects posteriorly
  • wider with successive inferior vertebrae
  • rectangular in median section
  • thickened posterior margin