Processes of vertebrae

A typical vertebra contains seven projections called the processes. They serve as the attachment sites for the back muscles and ligaments, levers for the actions of muscles and have facets for the articulation with adjacent vertebrae.

The typical vertebrae have one unpaired and three paired processes:

• Spinous process - a single process that projects posteriorly and inferiorly from the central aspect of the vertebral arch;
• Transverse process - one on each side, projects posterolaterally from the vertebral arch;
• Superior articular process - extends upward from the vertebral arch and contains the superior articular facet of the vertebra;
• Inferior articular process - extends downward from the vertebral arch and has the inferior articular facet of the vertebra.

The articular processes are located between the intersections of the pedicles and laminae. They form joints between adjacent vertebrae called the superior facet joints (superior zygapophyseal joints) and inferior facet joints (inferior zygapophyseal joints).