Of the three tubercles noticed in connection with the transverse processes of the lumbar vertebrae

Lumbar vertebrae

The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...

, the superior one is connected in the lumbar

Lumbar

In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum ...

 region with the back part of the superior articular process, and is named the mammillary process.

Attachments of mammillary process: The multifidi muscle attaches to the mammillary process and helps to stabilize the vertebral joints. It spans from the sacrum to the cervical, endowing stability to each segmental level.