Posterior view of cervical spine. There are seven cervical vertebrae that connect the head to the thorax. The first two vertebrae are unique and given individual names; atlas (C1) and axis (C2). The seventh vertebra possesses a long spinous process, which serves as a helpful landmark, and is called the vertebra prominens. The atlas is largely a ring of bone lacking a body. Its large lateral masses are connected by anterior and posterior arches. The superior articular processes are deeply concave to receive the occipital condyles at the atlantooccipital joint. This "yes" joint produces anterior/posterior flexion and extension. The axis has a body from which projects superiorly the odontoid process or dens. This process is held in place behind the anterior arch of the atlas by the strong transverse ligament of the atlas. The atlantoaxial joint is the "no" joint where most of head rotation occurs. The remaining cervical vertebrae are characterized by having small bodies that are attached to the neural arch by short pedicles, transverse processes that contain transverse foramina, and spinous processes that are usually bifid. The first intervertebral disc is located between the bodies of C2 and C3. Each vertebral body subsequently is bound by discs as symphyseal joints and resist compressive forces. The facet joints are synovial joints between associated superior and inferior articular processes and facets. The cervical spine is the most mobile of the vertebral regions. The vertebral arteries first enter (usually) the transverse foramen of the C6 vertebra and ascend through the remaining vertebrae. After passing through the transverse foramen of the atlas, the artery curves around its lateral mass and rests in a groove along the superior border of the posterior arch before ascending into the posterior fossa through foramen magnum. (Image courtesy of AL Rhoton, Jr.)