The upper cervical complex is one of the most important joints in the human body. Its unique anatomy is responsible for providing a highly mobile functional support for the skull, while protecting the spinal cord from injury. These joints are destinctive from other vertebral segments in that lack intervertebral disks, reling entirely upon a complex network of ligamentous structures to constrain movement of the boney structures. It is only when the cervical spine becomes dysfunctional that we begin to appreciate the importance of its role in the performance of daily activities.
We can enhance our ability to understand these extremely complex patterns of motion by subdividing the occipital-atlanto-axial joint into two motion segments C0/C1 and C1/C2, where each motion segment consists of two adjacent bony structures and their associated soft tissues. By summing the contribution of each motion segment, we are able to account for the total range of motion of the upper cervical spine. We always need to keep in mind that the occiput, atlas, and the axis function as a unit whose individual movements are closely coupled one to another.
The suboccipital muscles ( --- ), linking C0, C1, and C2, are sometimes overlooked because of their small size compared to the principle movers.
Suboccipital Muscles
Obliquus capitis superior
Obliquus capitis inferior
Rectus capitis posterior minor
Rectus capitis posterior major
The suboccipital muscles help stabilize the atlanto-occipital articulations and contain a high density of muscle spindles which may serve as a rich source of proprioceptive feedback to the central nervous system.
The attaches to the inion and extends to the C7 spinous process. It overlays and is intimately attached to each spinous process of the cervical vertebrae.
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