Which feature marks the most cranial boundary on a cervical spine radiograph?

• A. Occipital crest
• B. Atlas
• C. Nuchal crest
• D. Foramen magnum

Answer: (A)

The top boundary of the cervical spine on a radiograph is identified by the occipital region of the skull, specifically the occipital crest. This midline ridge marks where the skull ends and the cervical vertebrae begin, making it the most cranial landmark you can use when outlining the cervical series. The atlas sits just below this skull boundary as the first cervical vertebra, so it marks the start of the neck portion but not the actual cranial limit. The foramen magnum is an opening within the skull at the skull–spinal junction, and while related to brain–spine transition, it is not the primary radiographic boundary point used to define the cervical segment. The nuchal crest is another skull feature but is not the superior, most cranial boundary for the cervical spine on radiographs.