The cervical spine and the hyoid bone are essential elements of the bones of the neck. The cervical spine consists of the seven uppermost vertebrae of the vertebral column. C3 to C6 are referred to as typical cervical vertebrae and are generally characterized by the presence of transverse foramina as well as, in many people, bifid spinous processes. The cervical enlargement of the spinal cord runs through the large, triangular vertebral foramina, while the vertebral arteries and veins run through the transverse foramina bilaterally. C7 is known as vertebra prominens, owing to its particularly long, monofid spinous process, and it is distinct as the vertebral arteries do not pass through its transverse foramina, but rather, run past its transverse processes. The bodies of the typical cervical vertebrae are articulated via symphyses, which are typically separated by fibrocartilaginous intervertebral discs. The arches of the vertebrae articulate through synovial joints between articular facets. The vertebrae are then further supported by the several ligaments found throughout the spine, as well as the nuchal ligament, which is the thickened continuation of the supraspinous ligament. There are eight cervical spinal nerves associated with the cervical vertebrae.
C1 (atlas) and C2 (axis) are two specialized atypical vertebrae that, together with the occiput, form the atlanto-axial and atlanto-occipital joints. These joints are essential for the rotation and flexion of the head. The hyoid bone, which is U-shaped and typically found anteriorly in the neck around the level of C3, is unusual in the fact that it does not articulate with any other bones. Instead, it provides a point of attachment for a plethora of muscles and ligaments. The majority of these attach to the two greater horns located on the bone, with the sole exception of the stylohyoid ligament, which attaches to the lesser horns. The greater horns of the hyoid bone are then united in the center to form the body of the hyoid.
The anatomy of the typical cervical vertebrae is particularly noteworthy. The bodies of the vertebrae are characterized by the presence of vertebral foramina, transverse foramina, and in many cases, bifid spinous processes. The cervical enlargement of the spinal cord passes through the large, triangular vertebral foramina, while the vertebral arteries and veins run through the transverse foramina bilaterally. The bifid spinous process is distinct as it bifurcates into two processes and is most commonly found on C4, C5, and C6 vertebrae. The bodies of the typical cervical vertebrae are articulated via symphyses, which are typically separated by fibrocartilaginous intervertebral discs. The arches of the vertebrae then articulate through synovial joints between articular facets. Furthermore, the vertebrae are supported by several ligaments found throughout the spine, as well as the nuchal ligament, which is the thickened continuation of the supraspinous ligament. There are eight cervical spinal nerves associated with the cervical vertebrae.
C1 (atlas) and C2 (axis) are two specialized atypical vertebrae that, together with the occiput, form the atlanto-axial and atlanto-occipital joints. These joints are essential for the rotation and flexion of the head, and can thus be considered as the foundation of the neck’s mobility. C1 and C2 vertebrae differ in appearance from the typical cervical vertebrae, as C1 does not have a body, only an atlas plate and anterior arch, while C2 has the dens. The dens of the axis vertebra is a bony protrusion located on the anterior surface of C2, which looks like a peg and fits into the atlas vertebra’s atlantal facet to form the important atlanto-axial joint.
The hyoid bone is a U-shaped bone that is located anteriorly in the neck around the level of C3. This bone is distinct in that it does not articulate with any other bones, but rather, serves as a point of attachment for an array of muscles and ligaments. Most of these attach to the two greater horns of the hyoid bone, with the singular exception of the stylohyoid ligament, which attaches to the lesser horns. The two greater horns of the hyoid bone ultimately converge to form the body of the hyoid.
The cervical spine, along with the hyoid bone, serve a range of important functions. The vertebrae primarily provide support for the neck, while allowing for a great range of motion. The seven vertebrae form an S-shaped curve and are held in place by musculature, along with various ligaments, such as the nuchal ligament, the supraspinous, and the posterior longitudinal ligaments. This musculature and ligamentous support allow for various motions such as flexion, lateral flexion, extension, and rotation. The C1 and C2 vertebrae are of particular importance as, together with the occiput, they form the atlanto-axial and atlanto-occipital joints, which provide the head with a great deal of mobility.
The hyoid bone is also an essential element of the neck and functions in several ways. First, it serves as a point of attachment for various muscles, such as the stylohyoid muscles, the sternohyoid, mylohyoid, digastrics, and geniohyoid muscles. These muscles interact with the hyoid bone and are the primary muscles that allow for tongue movement. Additionally, the hyoid bone is essential for breathing as it helps to stabilize the larynx during respiration. The hyoid bone also functions as a point for the attachment of ligaments. For example, the stylohyoid ligament connects the hyoid bone to the styloid process of the temporal bone, and the hyoepiglottic ligament connects the hyoid bone to the epiglottis.
The cervical spine and the hyoid bone can be affected by a number of pathologies, which can lead to a variety of symptoms and complications. Common conditions that affect the cervical spine include whiplash, cervical spondylosis, cervical disc herniation, and cervical muscular strain. Symptoms of conditions that affect the cervical spine can include pain, tingling, numbness, and weakness. Similarly, the hyoid bone can be affected by conditions such as subluxation, displacement, fracture, and inflammation. Generally, symptoms include pain, difficulty swallowing, and difficulty breathing.
In addition to conditions that affect the cervical spine and hyoid bone directly, there are also conditions in which the cervical spine and hyoid bone can play an important role in diagnosis and treatment. For instance, Disorders of the Temporomandibular Joint (TMJ) can cause pain and dysfunction in the upper cervical spine and hyoid bone. In these cases, proper evaluation of the cervical spine and hyoid bone is necessary for diagnosis and the development of an effective treatment plan. Additionally, conditions such as temporomandibular joint dysfunction can be treated with the use of manual therapies, such as spinal manipulation, which can help to restore mobility to the cervical spine and hyoid bone.
The cervical spine and the hyoid bone are essential elements of the neck, and are important for supporting the neck, providing mobility to the head, and playing a role in breathing, swallowing, and tongue movement. In addition, these structures can be affected by various conditions, and can also play a role in diagnosis and treatment of other conditions such as disorders of the temporomandibular joint. Thus, it is evident that the cervical spine and hyoid bone are both integral for the proper functioning of the neck.
