When evaluating an anteroposterior (AP) open-mouth projection of the cervical spine, which two structures should be visualized on an acceptable radiograph?

In an anteroposterior (AP) open-mouth projection of the cervical spine, the primary structures that should be visualized are the lateral masses of C1 (the atlas) and the odontoid tip (thedens or odontoid process of C2).

The lateral masses of C1 are important for assessing the alignment of the cervical spine and any potential fractures or misalignments. They allow for the evaluation of the relationship between the first and second cervical vertebrae. Visualizing these lateral masses helps in determining normal anatomy and pathology in the upper cervical region.

The odontoid tip is crucial because it represents the key structure for rotation of the cervical spine. In a good AP open-mouth radiograph, it provides important information on the integrity of the upper cervical spine. The position of the odontoid process can indicate rotary subluxation or other deformities.

Seeing both the lateral masses of C1 and the odontoid tip confirms that the radiograph effectively demonstrates the pertinent anatomy of the upper cervical spine, which is essential for accurate diagnosis and treatment planning.