The structure indicated is the superior articular process.

There are 33 vertebrae which make up the spinal column:

• 7 cervical
• 12 thoracic
• 5 lumbar
• 5 fused sacral vertebrae
• 3-4 fused coccygeal vertebrae

The typical vertebra consists of the following features:

• Vertebral body
• Vertebral arch (neural arch) consisting of lamina and pedicle
• Spinous process
• Transverse process
• Vertebral foramen (collectively form vertebral canal)
• Superior and inferior articular processes
• Superior and inferior vertebral notches

The superior articular process articulates with the inferior articular process of the vertebrae above. These articulations are known as zyapophysial joints.

The articular processes arise from the junction between the laminae and pedicles of the vertebral arch.

Learn more about the anatomy of the vertebrae in this tutorial.