Cervical Spine and Soft Tissues of the Neck
Anatomy—Cervical Spine and Soft Tissues of the Neck
This section will highlight anatomical landmarks of the cervical spine, specifically the cervical vertebrae.
As cone beam CT scans are not made to differentiate soft tissue, this chapter will not identify specific soft tissue anatomy. It will look at more general areas, many of which are only identifiable when using a scan with a large field of view.
There are many variations of developmental anomalies that may present in the cervical vertebrae. This book cannot encompass them all and will list some of the most commonly occurring ones. The developmental anomalies are listed in order of most superior cervical vertebrae moving inferiorly.
They are incomplete fusions of the ossification centers of either the anterior or posterior arch of C1 (atlas) or a combination of both. The fusion of the anterior arch occurs by the age of 10 and the posterior arch completes fusion between the ages of 3 or 4. Posterior arch clefts have an incidence of 4% of all adults with 97% of these clefts occurring in the midline. Anterior arch clefts are less common, occurring in only 0.1% of all adults. Cervical vertebral clefts occur more commonly in patients with cleft lip, cleft palate, or both.
It appears as a well-defined radiolucent line or band of the anterior or posterior arch of C1. There may be multiple radiolucent lines (thee or more) visible in the anterior arch (Figure 7.11). The posterior arch rarely presents with more than one radiolucent line. The bony borders of the arch and ossification centers are corticated. When both anterior and posterior clefts are noted, the appropriate descriptive term is split atlas. This is best visualized on axial and coronal views (Figures 7.12 and 7.13).
Radiolucent line(s) in the anterior or posterior arch of C1 that are not corticated means one would need to consider the possibility of a fracture. A fracture typically presents with swelling combined with a history of trauma to the area.
There is no recommended treatment or further imaging necessary for this finding.
Os Terminale (C2)
There are three ossification centers that develop to form the body of C2 (axis). Two form the body and one forms the tip of the odontoid process. The ossification center that forms the tip of the odontoid process is referred to as os terminale. It is typically evident by the age of 3 and fuses with the body of C2 by the age of 12. It has been reported in 1.3%–9.9% of children.
Os terminale presents as a well-defined radiopaque entity at the tip of the body of C2. The body of C2 has a V-shaped notch on thesuperior aspect where the ossification center is located on coronal views (Figure 7.14). There is a complete to incomplete radiolucent line separating the ossification center from the remainder of the body of C2. This is best visualized on coronal and sagittal views (Figure 7.15).