The structure indicated is the pedicle of the vertebra.
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 vertebral arch is formed from two pedicles and two laminae. The pedicles attach on either side to the posterolateral aspects of the vertebral body and unite posteriorly with the laminae which complete the vertebral arch.
Learn more about the anatomy of the vertebrae in this tutorial.