The PSA innervates teeth on the maxilla. Which option best describes its target and nuance?

• A. Central Incisors only
• B. First, Second, and Third Maxillary Molars
• C. All Maxillary Teeth
• D. First, Second, and Third Maxillary Molars, but may not innervate MB root of the maxillary 1st molar

Answer: (D)

The posterior superior alveolar nerve primarily supplies the maxillary molars. It typically innervates the first, second, and third maxillary molars, but there is a notable variation: the mesiobuccal root of the first maxillary molar is often supplied by the middle superior alveolar nerve rather than by the PSA alone. Therefore, the most accurate description is that the PSA covers the molars, with the MB root of the first molar potentially not being innervated by PSA. In practice, if you’re relying on a PSA block to numb that MB root, you may need additional anesthesia (such as an MSA block or targeted infiltration) to ensure complete numbness.