What is the target area for an MSA nerve block?

• A. Maxillary bone above the apex of the maxillary second premolar
• B. Inferior orbital rim
• C. Infraorbital canal
• D. Nasopalatine canal

Answer: (A)

The MSA block is designed to anesthetize the middle superior alveolar nerve as it travels through the buccal aspect of the maxilla to the premolar teeth. The nerve commonly courses near the apex of the second maxillary premolar, so placing anesthetic into the mucobuccal fold over that tooth and right against the bone targets the nerve before it enters the tooth sockets. That’s why the area right above the apex of the second premolar is the correct target.

Other areas described don’t align with where the MSA nerve runs or where this block is delivered. The infraorbital canal and the inferior orbital rim refer to deeper or more superior paths not typically targeted for the MSA block. The nasopalatine canal is in the palate and relates to a different nerve. Therefore, depositing near the bone above the second premolar apex best achieves anesthesia of the premolar region via the MSA nerve.