SNA Angle — NDEB AFK MCQ
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Correct answer: D — Maxillary anteroposterior position relative to the cranial base
The SNA angle measures the anteroposterior (sagittal) position of the maxilla relative to the anterior cranial base. S = Sella, N = Nasion, A = Point A (deepest concavity of the anterior maxilla). The normal SNA is approximately 82° (±2°). SNA > 84° indicates maxillary prognathism. SNA < 80° indicates maxillary retrognathism. SNB measures the mandibular position. ANB (SNA minus SNB) describes the skeletal anteroposterior jaw relationship.
Reference: Proffit – Contemporary Orthodontics, 6th ed., 2019