• Hart J

• Atlanto-Axial Joint / diagnostic imaging
• Cervical Vertebrae / diagnostic imaging
• Odontoid Process / diagnostic imaging
• Radiology / history

METHODS: Searches in PubMed, standard radiography texts, and telephone interviews.

RESULTS: The AP open-mouth radiograph has a long history of use in the chiropractic and medical professions. The view is taken to assess the upper cervical vertebrae (C1 and C2), and some chiropractors include assessment of the atlantooccipital articulation by using the AP open-mouth radiograph procedure. One text cited a 1910 background reference for this view, but further investigation revealed an earlier edition of the 1910 publication, which gave a description of how to take an AP open-mouth radiograph. The first documentation that this view had been taken was found in a 1919 chiropractic text. Chiropractors appear to have been the first to include an atlantooccipital biomechanical analysis with the AP open-mouth radiograph.

CONCLUSION: The origins of the AP open-mouth radiograph date back to the early 1900s. A medical doctor in Germany appears to have been the first to describe the procedure for this radiographic view. By the 1930s, chiropractors were including the occiput in the view's analysis, along with the traditional application of C1 and C2 assessment.

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