Vertebrae, along with intervertebral discs, form the vertebral column, or spine. It extends from the base of the skull to the coccyx and includes the cervical, thoracic, lumbar, and sacral regions. The spine has several significant roles in the body that include: protection of the spinal cord and branching spinal nerves, structural support, and allows for flexibility and mobility of the body. The intervertebral discs are cartilaginous structures between adjacent vertebrae that support the spine by acting as shock-absorbing cushions to the axial loading of the body. The cervical spine has seven vertebral bodies, numbered C1 to C7, counting from the base of the skull to the thoracic spine. The structure of C1, C2, and C7 have distinctive properties that make them unique in comparison to the typical cervical vertebrae, C3 to C6. The anatomy of C3 to C6 consists of a vertebral body, a vertebral arch, as well as seven processes. The vertebral arch is comprised of the pedicles, bony processes that project posteriorly from the vertebral body, and the lamina; these are the bone segments that form most of the arch. Together, the pedicles and the lamina form a ring around the spinal canal, which harbors the spinal cord. Completing the typical vertebra are seven processes, and they include two superior articular facets, two inferior articular facets, one spinous process, and two transverse processes that allow the passage of the vertebral vasculature. There are three atypical vertebrae in the cervical region. C1 (atlas) articulates with the base of the skull and is unique in that it does not contain a body due to fusion with the C2 (axis) vertebrae, acting as a pivot point for the Atlas to rotate. The most distinctive feature of the C2 vertebra is the presence of an odontoid process (dens) that rises from the superior aspect of its body and articulates with the posterior surface of the anterior arch of C1. C7 has two distinct features that make it unique to a typical cervical vertebra: first, the vertebral vasculature does not traverse through its transverse foramina, and second, it contains along the spinous process, making C7 to be commonly known as “vertebra prominens.” While there are seven cervical vertebrae, there are eight pairs of cervical nerves, numbered C1 to C8. Each pair of cervical nerves emerge from the spinal cord superior to their corresponding vertebra, except for C8, which exits inferiorly to the C7 vertebra. Cervical disc herniation is the result of the displacement of the nucleus pulposus of the intervertebral disc, which may result in impingement of these traversing nerves as they exit the neural foramen or directly compressing the spinal cord contained within the spinal canal.
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