The lumbar vertebrae contain a large vertebral body. The spinous processes are thickened at their ends and are positioned almost horizontally. On the lumbar side the transverse processes are also known as the costal processes, because they are rudiments of the ribs. The accessory processes are rudimentary transverse processes and are located dorsally from the costal processes. Cranially from the accessory process another nipple-shaped protrusion can be found: the mamillary process. The vertebral body of L4 forms the bottom of the lumbar lordosis.
