Anatomy & Histology · single question
The middle superior alveolar (MSA) nerve primarily anesthetizes which teeth?
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Correct answer: C. Maxillary first and second premolars and mesiobuccal root of first molar
The middle superior alveolar nerve (a branch of the infraorbital nerve) innervates the maxillary first and second premolars and the mesiobuccal root of the maxillary first molar. It is present in approximately 28–72% of patients (it is the most variable of the three superior alveolar nerves). The anterior superior alveolar (ASA) nerve covers the central, lateral, and canine; the posterior superior alveolar (PSA) covers the remaining molar roots.
- A. ❌ The canine is innervated primarily by the ASA nerve.
- B. ❌ 'All posterior teeth' would include the full extent of PSA and MSA coverage combined.
- C. ✅ CORRECT – The MSA nerve covers the premolars and mesiobuccal root of the maxillary first molar.
- D. ❌ The central and lateral incisors are covered by the anterior superior alveolar (ASA) nerve.
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