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Middle Superior Alveolar Nerve

nervus alveolaris superior medius

The middle superior alveolar nerve is an inconstant branch of the infraorbital nerve (V2) present in approximately 50% of individuals. When present, it descends in the lateral wall of the maxillary sinus to supply the upper first and second premolar teeth and the mesiobuccal root of the first molar. It forms part of the superior dental plexus together with the anterior and posterior superior alveolar nerves.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The inconstancy of the middle superior alveolar nerve explains the variable success of maxillary nerve blocks for the upper premolars. When absent, the premolars are supplied by the adjacent anterior or posterior superior alveolar branches. Sinus lift procedures and implant placement in the posterior maxilla can damage these fine nerves in the lateral sinus wall, causing altered sensation in the upper premolar region. The superior dental plexus formed by the three superior alveolar nerves provides significant overlap of sensation, making complete anaesthesia of individual teeth require supplemental infiltration.

Pathology

Common Injuries & Conditions

Variable Anaesthesia of Upper Premolars

The absence of the middle superior alveolar nerve in approximately 50% of patients means that supplemental buccal or palatal infiltration is often required beyond a standard posterior superior alveolar block to achieve complete anaesthesia of the upper first premolar and its premolar neighbours.