Osteology of the Vertebral Column: Cervical Vertebrae

C1 and C2 are extremely specialized in their morphology.  Like typical cervicals, they possess transverse formanina.  However, their bodies are either lacking entirely or highly modified.  C1, or the atlas vertebrae, lacks a body entirely.  Its superior articular facets are cup shaped and face superiorly to receive the occipital condyles. The motion of the head nodding “yes” is the result of the occipital condyles sliding across the superior articular facets of the atlas. The inferior articular surfaces of the atlas are oriented transversely, to complement the transversely oriented superior articular facets of C2, the axis vertebra.  These transversely oriented facets can slide across one another to permit rotational movement.

The axis has a highly modified body which resembles the body of a typical cervical vertebra from an inferior view, but projects superiorly as a rounded structure called the dens. The dens articulates with a fovea on the anterior arch of the atlas.  This peculiar vertebral articulation allows the head and atlas to rotate around the dens of the axis, more than making up for the restrictions on rotation imposed by the interlocking bodies of the typical cervical vertebrae.  The inferior articular facets of the axis resemble those of typical cervical vertebrae.

The bodies of the cervical vertebrae are generally small and are not flat as in other vertebral classes.  The superior margin of the body has raised lateral margins, while the inferior margin has raised ventral and dorsal margins.  Thus, the bodies of two adjacent cervical vertebrae interlock slightly, limiting rotational movement in the cervical region.  The superior and inferior articular facets are generally planar, or somewhat concave.  The articular plane of both superior and inferior facets is oriented parallel to the long axis of the body, but is obliquely tilted such that it slopes from superior-ventral to inferior-dorsal.

The transverse processes of typical cervical vertebrae are extremely small and inconspicuous. Spinous processes are short, medial-laterally broad and superior-inferiorly compressed.  They are often bifid, or split into two at the end of the process.

The bodies of the cervical vertebrae are generally small and are not flat as in other vertebral classes.  The superior margin of the body has raised lateral margins, while the inferior margin has raised ventral and dorsal margins.  Thus, the bodies of two adjacent cervical vertebrae interlock slightly, limiting rotational movement in the cervical region.  The superior and inferior articular facets are generally planar, or somewhat concave.  The articular plane of both superior and inferior facets is oriented parallel to the long axis of the body, but is obliquely tilted such that it slopes from superior-ventral to inferior-dorsal.

The transverse processes of typical cervical vertebrae are extremely small and inconspicuous. Spinous processes are short, medial-laterally broad and superior-inferiorly compressed.  They are often bifid, or split into two at the end of the process.

The bodies of the cervical vertebrae are generally small and are not flat as in other vertebral classes.  The superior margin of the body has raised lateral margins, while the inferior margin has raised ventral and dorsal margins.  Thus, the bodies of two adjacent cervical vertebrae interlock slightly, limiting rotational movement in the cervical region.  The superior and inferior articular facets are generally planar, or somewhat concave.  The articular plane of both superior and inferior facets is oriented parallel to the long axis of the body, but is obliquely tilted such that it slopes from superior-ventral to inferior-dorsal.

The transverse processes of typical cervical vertebrae are extremely small and inconspicuous. Spinous processes are short, medial-laterally broad and superior-inferiorly compressed.  They are often bifid, or split into two at the end of the process.

The bodies of the cervical vertebrae are generally small and are not flat as in other vertebral classes.  The superior margin of the body has raised lateral margins, while the inferior margin has raised ventral and dorsal margins.  Thus, the bodies of two adjacent cervical vertebrae interlock slightly, limiting rotational movement in the cervical region.  The superior and inferior articular facets are generally planar, or somewhat concave.  The articular plane of both superior and inferior facets is oriented parallel to the long axis of the body, but is obliquely tilted such that it slopes from superior-ventral to inferior-dorsal.

The transverse processes of typical cervical vertebrae are extremely small and inconspicuous. Spinous processes are short, medial-laterally broad and superior-inferiorly compressed.  They are often bifid, or split into two at the end of the process.

C7 is transitional in morphology between cervical and thoracic vertebrae.  Like a typical cervical vertebra, it bears distinctive transverse foramina. However, the spinous processes and transverse processes are much more pronounced and longer, thus resembling thoracic vertebrae.