The sella-nasion-subspinale angle (SNA) relates to the horizontal position of which structure?

The sella-nasion-subspinale angle (SNA) is an important cephalometric measurement used in orthodontics and dental assessment to evaluate the anterior-posterior position of the maxilla concerning the cranial base. Specifically, this angle reflects the relationship between the maxilla (represented by the point subspinale) and the reference plane established by the cranial base (line derived from the sella to nasion).

By using the cranial base as a reference, the SNA angle helps to determine whether the maxilla is positioned normally, protruded, or retruded relative to the skull. This measurement is crucial for diagnosing and planning treatments for dental and orthodontic concerns, as deviations in this angle can have significant implications on facial balance and occlusion.

In contrast, the other options focus on different anatomical references that do not specifically assess the horizontal position of the maxilla concerning the cranial base. For example, the Frankfurt horizontal relates to the orientation of the skull in a horizontal plane, the mandibular plane involves the relationship of the mandible, and the occlusal plane pertains to the alignment of the dental arches. Each of these measurements serves a distinct purpose but does not directly relate to the SNA's assessment of the max