American Registry of Radiologic Technologists (ARRT) Practice Exam

In the Townes view, which structures are projected through the Foramen Magnum?

1. Dorsum sellae and posterior clinoid process

2. Dorsum sellae and anterior clinoid process

3. Maxillary sinuses and ethmoidal air cells

4. Frontal sinuses and orbits

The correct answer is: Dorsum sellae and posterior clinoid process

In the Townes view, the primary structures that are projected through the Foramen Magnum are the dorsum sellae and the posterior clinoid process. This projection is significant in neuroimaging as it allows for a clear visualization of the clivus and surrounding structures in the skull. The dorsum sellae, which is the posterior part of the sella turcica, is particularly important for identifying the position and shape of the pituitary gland, as well as assessing potential pathologies in that area. The posterior clinoid processes serve as important landmarks for the dural attachments in the cranial cavity. Achieving an image where these structures are clear and well-defined helps in diagnosing conditions that might affect the sella turcica and the brainstem, contributing to accurate assessments in radiologic evaluations. In contrast, the other options pertain to different cranial structures that would not be primarily visualized through the Foramen Magnum in the Townes view. For instance, the anterior clinoid process and various sinuses are positioned in a manner that does not relate to the specific anatomy being assessed with this particular radiographic technique. Understanding the anatomical landmarks highlighted in different radiographic views is crucial for accurate image interpretation and diagnosis in