Caption

Photograph of the human third and fourth lumbar vertebrae (L3 & L4), two of five bones that comprise the lumbar spine of the lower back. The vertebrae are seen in anterior aspect with superior surface at bottom: in other words, one is looking at the front of the bones, which are upside down. Lumbar vertebrae have large, wide bodies, with short, thickened bony processes for the attachment of the strong muscles of the lower back. The left & right transverse processes are seen protruding from the vertebral bodies. The lumbar vertebrae are the largest of the unfused vertebrae in the backbone.