The structural unit of the spine is called a vertebra. There are slight differences in structure as the vertebrae are located in different parts of the spine. A typical vertebra consists of three segments. Centrum, neural arch and neural foramen/canal.
1. Centrum: The main part of the vertebra is the centrum. It is large and oval in shape. It is hard, thick and spongy bone.
2. Neural arch: The ring or ring-like part formed from the surface of the vertebrae is called arch. The parts of the arch are:
(i) Pedicle: Thick, short and hard bone formed from the back of vertebra is called pedicle.
(ii) Transverse process: Both the extensions arising from the junction of pedicle and lamina are called transverse processes.
(iii) Lamina : The lamina is a flat, flat and plate-like bone lying between the transverse process and the spinous process.
(iv) Articular process or Zygapophysis: Each vertebra has pre-zygapophysis (superior) anteriorly and post-zygapophysis (inferior) posteriorly. The superior articular process of one vertebra articulates with the inferior articular process of another vertebra.
(v) Spinus process : The amplifier arising from lamina is called spinous process.
3. Neural foramen/canal
(i) Intervertebral foramen: The hole in the pedicle is called intervertebral foramen. It contains smooth nerves and blood vessels.
(ii) Vertebral foramen: The large opening in each vertebra is called vertebral foramen.
(iii) Vertebral canal: Vertebral foramen of vertebrae join together to form vertebral canal.