Which nerve supplies the maxillary premolars (teeth 4, 5, 12, 13) and, sometimes, the mesiobuccal root of the first molar?

Which nerve supplies the maxillary premolars (teeth 4, 5, 12, 13) and, sometimes, the mesiobuccal root of the first molar?

• A. MSA
• B. PSA
• C. ASA
• D. Infraorbital nerve

Answer: (A)

The key idea is that the middle superior alveolar nerve is the branch of the maxillary division that specifically supplies the maxillary premolars. It innervates teeth 4, 5, 12, and 13, and in some individuals it also provides innervation to the mesiobuccal root of the first maxillary molar. The premolar region gets this input from the MSA, which can arise from the infraorbital nerve; when present, the MSA is the direct source for those premolars. In people where the MSA is absent, the innervation for those premolars can instead come from branches of the PSA or from the ASA, but the classic and most direct supplier for these premolars is the middle superior alveolar nerve.

The key idea is that the middle superior alveolar nerve is the branch of the maxillary division that specifically supplies the maxillary premolars. It innervates teeth 4, 5, 12, and 13, and in some individuals it also provides innervation to the mesiobuccal root of the first maxillary molar. The premolar region gets this input from the MSA, which can arise from the infraorbital nerve; when present, the MSA is the direct source for those premolars. In people where the MSA is absent, the innervation for those premolars can instead come from branches of the PSA or from the ASA, but the classic and most direct supplier for these premolars is the middle superior alveolar nerve.