Anatomy of the Cervical Spine and Neck
The anatomy of the neck and specifically the cervical spine is extremely important to understand. The cervical spine sits upon the top of the spinal column. It is comprised of seven cervical vertebrae, C1-C7, which enclose the spinal cord and meninges. These vertebrae are stacked upon one another and provide the flexibility and stability to allow proper positioning of the skull. The bodies of these cervical vertebrae are smaller than when compared to the other regions of the spinal column, showing that they do not have as much weight bearing responsibilities as those same other regions referred to before. The intervertebral discs are also smaller than that of the thoracic, lumbar and sacral regions, but in relation to the size of the cervical vertebrae they are relatively thick. This allows for the wide variety of movement allowed at the neck.
The C3-C7 vertebrae are considered normal vertebrae and have larger openings for the nervous and vasculature accommodations due to the enlargement of the spinal cord in the cervical region because of the innervation that it supplies to the upper extremity. The C1 and C2 vertebrae are considered atypical. The C1 vertebrae or “atlas” does not have a body or a spinous process. This bears the weight of the cranium and due to it being the widest vertebrae in the cervical region, it allows for increased stability and articulation with the musculature that attaches here. The C2 vertebrae or “axis” is the strongest of the cervical vertebrae. It also holds the weight of the cranium and allows the C1 vertebrae to rotate upon it. The distinct feature of this vertebrae is that it contains an odontoid process, or “dens” that, with the spinal cord, is encompassed by the atlas. The importance of the dens is that it acts as the specific pivot point of where the head turns. The dens is anterior to the spinal cord, and is held into position by the transverse ligament. This ligament prevents the dens from being displaced posteriorly and the spinal cord being displaced anteriorly. This upholds the integrity of the superior spinal column and avoids compromise of the spinal cord as it ascends into the base of the skull and brain.
In terms of the anatomy we just covered I do want to touch on two major joints that help make up the cervical spine anatomy, which are the craniovertebral joints. The two types of joints we are talking about are the atlanto-occipital joints and the atlanto-axial joints. The atlanto-occipital joints are the articulations between the lateral aspects of the atlas and the occipital condyles. These joints are important because they allow flexion and extension of the neck in addition to minor lateral flexion and rotation. The atlanto-axial joint has three articulations: the right and left lateral atlanto-axial joints and the median atlanto-axial joint. The movements that the combination of these three articulation provide are rotation.
The neck and cervical spine have dozens of other structures but without getting too far ahead of ourselves, we will touch on the major musculature of each area of the neck. In the sternocleidomastoid region of the neck, we have the platysma, sternocleidomastoid, and trapezius. In the anterior cervical region we have the mylohyoid, geniohyoid, stylohyoid, digastric, sternohyoid, omohyoid, sternothyroid, and thyrohyoid. In the deep anterior and posterior regions of the neck we have longus colli, longus capitis, rectus capitis anterior, anterior scalene, rectus capitis lateralis, splenius capitis, levator scapulae, middle scalene, and posterior scalene. Again this is not an exhaustive list, but to get a baseline understand of the structures in the neck is important because injury to the cervical spine can be catastrophic if not handled properly. If you have had any neck injuries, or would like to see specific structures, injuries or conditions discussed in future articles, please let us know and always remember to #HealByMoving.