The C6 vertebra is the sixth cervical vertebra of the spine. It is found in the base of the neck between the C5 and the last cervical vertebra, C7. The C6 vertebra plays an important role in supporting and protecting the structures of the head and neck as well as anchoring the muscles that move and support the neck.
The C6 vertebra is located in the inferior end of the neck just above the thorax. It is the second most inferior cervical vertebra as well as the second largest; only the C7 vertebra is larger and more inferior.
The anterior region of the C6 vertebra is made of a short cylinder of bone known as the centrum or vertebral body. The centrum forms a column continuous with the neighboring vertebrae, connected by the intervertebral disks. The intervertebral disks are thin masses of tough fibrocartilage with a soft, gel-like center. Each disk acts as a shock absorber for the spine while helping to hold the vertebral column in alignment. The transverse processes extend laterally from the centrum and contain small holes known as the transverse foramina. The vertebral arteries and veins pass through the foramina, along with some nervous tissue.
A bony ring known as the vertebral arch extends laterally and posteriorly from the centrum to surround the spinal cord and provide attachment points for the muscles of the neck. The pedicles of the vertebral arch extend from the left and right sides of the centrum posteriorly and laterally before widening into the superior and inferior articular processes. The articular processes form planar synovial joints with the neighboring vertebrae, allowing the neck to rotate and providing greater mobility to the head. The superior articular process is slightly convex to join with the concave inferior process of the C5 vertebra. Conversely, the inferior articular process is concave to match up with the convex superior articular process of the C7 vertebra. Posterior to the articular processes, the vertebral arch continues posteriorly and medially as the laminae, which meet at the body’s midline to complete the arch. From this union, the bone continues posteriorly for a short distance as the thin, flat spinous process that can be felt through the skin on the back of the neck.
The C6 vertebra plays a vital role in supporting and protecting the tissues of the neck. The spinal cord passes through the vertebral foramen and is protected by the bony tissue of the C6 vertebra. Likewise, the vertebral arteries and veins pass through and are protected by the transverse foramina.
Several muscle groups attach to the C6 vertebra to move and support the neck. Rotatores muscles connect to the transverse process to rotate the neck, while the longissimus muscle pulls on the transverse process to laterally flex the neck. The trapezius muscle of the back has one of its origins on the spinous process of the C6 vertebra. Also connected to the spinous process is the thin multifidus muscle, which helps to support the neck and maintain the body’s posture.