Cervical Disc Herniation

Excerpt

Vertebrae, along with intervertebral discs, form the vertebral column, or spine, extending 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, including protecting the spinal cord and branching spinal nerves, providing structural support, and allowing for the 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 consists of 7 vertebral bodies, numbered C1 to C7, extending from the skull's base to the thoracic spine. The structure of C1, C2, and C7 has 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, and 7 processes. The vertebral arch comprises the pedicles, bony processes that project posteriorly from the vertebral body, and the lamina, which form most of the bony arch. The pedicles and the lamina form a ring around the spinal canal, which harbors the spinal cord. Completing the typical vertebra are 7 processes, which include 2 superior articular facets, 2 inferior articular facets, 1 spinous process, and 2 transverse processes that allow the passage of the vertebral vasculature.

There are 3 atypical vertebrae in the cervical region. C1 (atlas) articulates with the base of the skull. C1 is unique in that it does not contain a body, due to the fusion of the embryological equivalent of the C1 vertebral body with the C2 (axis) vertebrae, which acts as a pivot point for the atlas to rotate. The most distinctive feature of the C2 vertebra is an odontoid process (dens), which arises from the superior aspect of its body and articulates with the posterior surface of C1's anterior arch. C7 is distinguished from other cervical vertebrae by 2 key features: its transverse foramina do not transmit vertebral vessels, and it has an especially long spinous process, which is why it is often called the “vertebra prominens."

While there are 7 cervical vertebrae, there are 8 pairs of cervical nerves, numbered C1 to C8. Each pair of cervical nerves emerges from the spinal cord superior to their corresponding pedicle, except for C8, which exits inferiorly to the C7 pedicle. 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.