Unit 2 of 7
The maxilla
The upper jaw: where its front sits, and how far forward that is.
The card
The maxilla is read as one question — how far forward is it — and SNA is the answer. Two of its three points are the ends of the palatal plane; the third is the concavity that carries the whole sagittal verdict for the upper jaw.
- ANS and PNS are the ends of the hard palate, and the plane between them is what upper incisor inclination is measured against.
- A point is the deepest concavity between ANS and the alveolar crest, measured against the facial line rather than against the page.
- SNA is the angle at Nasion between S–N and N–A. It says how far forward the maxilla sits on the cranial base.
What you will place