More commonly, subluxation occurs at the C6/C7 level (50% of cases). Such an injury may well lead to spinal cord involvement, and as a consequence quadriplegia or death may occur. This often happens at the C2 level, where the body of C2 moves anteriorly with respect to C3. The worst-case scenario for these injuries is that dislocation or subluxation of the cervical vertebrae occurs. Again, since the vertebral foramen is large there is less chance of spinal cord involvement. In more severe cases, fractures can occur to any of the cervical vertebrae as they are suddenly compressed by rapid deceleration. In minor cases, the anterior longitudinal ligament of the spine is damaged which is acutely painful for the patient. Hyperextension (Whiplash) InjuryĪ rear-end traffic collision or a poorly performed rugby tackle can both result in the head being whipped back on the shoulders, causing whiplash. However, there may be damage further down the vertebral column. Since the vertebral foramen is large, it is unlikely that there will be damage to the spinal cord at the C1 level. If the fall occurs with enough force, the transverse ligament of the atlas may also be ruptured. This causes them to be driven apart, fracturing one or both anterior/posterior arches. diving into excessively shallow water can compress the lateral masses of the atlas between the occipital condyles and the axis. nodding.Ĭlinical Relevance: Injuries to the Cervical Spine Jefferson Fracture of the AtlasĪ vertical fall onto an extended neck e.g. These are condyloid type synovial joints, and permit flexion at the head i.e. They occur between then superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. The atlanto-occipital joints consist of an articulation between the spine and the cranium. Medial atlanto-axial joint – formed by the articulation of the dens of C2 with the articular facet of C1.Lateral atlanto-axial joints (x2) – formed by the articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2.The atlanto-axial joints are formed by the articulation between the atlas and the axis: There are two joints unique to the cervical spine – the atlanto-axial (x3) and atlanto-occipital joints (x2). Between vertebral arches – formed by the articulation of superior and inferior articular processes from adjacent vertebrae.This is a type of cartilaginous joint, known as a symphysis. Between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage. There are two different joints present throughout the vertebral column: The joints of the cervical spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the cervical spine. The axis also contains superior articular facets, which articulate with the inferior articular facets of the atlas to form the two lateral atlanto-axial joints. This allows for rotation of the head independently of the torso. The dens articulates with the anterior arch of the atlas, in doing so creating the medial atlanto-axial joint. The axis (C2) is easily identifiable due to its dens (odontoid process) which extends superiorly from the anterior portion of the vertebra. The posterior arch has a groove for the vertebral artery and C1 spinal nerve. This is secured by the transverse ligament of the atlas – which attaches to the lateral masses. The anterior arch contains a facet for articulation with the dens of the axis. Instead, the atlas has lateral masses which are connected by an anterior and posterior arch. Each lateral mass contains a superior articular facet (for articulation with occipital condyles), and an inferior articular facet (for articulation with C2). It differs from the other cervical vertebrae in that it has no vertebral body and no spinous process. The atlas is the first cervical vertebra and articulates with the occiput of the head and the axis (C2). The atlas and axis have additional features that mark them apart from the other cervical vertebrae. Fig 2 – Characteristic features of a cervical vertebrae Atlas and Axis
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