Full L4 (4th Lumbar Vertebra) Description
[Continued from above] . . . intervertebral discs between the relatively flat surfaces of the centrum that form the articular facets of the joints between superjacent and subjacent vertebrae (the L3 and L5, respectively). The nearly horizontal and rectangular spinous process is likewise substantial, in order to counteract the force of strong muscles in the lower back that attach to it. As for the rest of the vertebral arch, it includes short, strong pedicles with superior and inferior notching; thick laminae; and thin, long transverse processes all surrounding a relatively large, triangular vertebral process through which the spinal cord passes safely. Between each transverse process and pedicle there is a superior articular process and an inferior articular process, each with a facet that articulates with the complementary facet of the vertebra above and below the L4, respectively. The L4 vertebra's transverse processes are noteworthy for lacking transverse foramina, as with the other lumbar vertebrae. Also consistent with the lumbar region of the spine, the centrum lacks external articular facets.