The middle superior alveolar nerve or middle superior dental nerve is a sensory branch of the infraorbital nerve, which is a branch of the maxillary nerve (CN V2). It typically arises within the infraorbital canal of the maxilla and descends along the lateral wall of the maxillary sinus. The nerve contributes to the superior dental plexus and supplies the sinus mucosa, the roots of the maxillary premolars, and the mesiobuccal root of the first maxillary molar. It is not always present; in 72% of cases it is non existent with the anterior superior alveolar nerve innervating the premolars and the posterior superior alveolar nerve innervating the molars, including the mesiobuccal root of the first molar. It is clinically relevant in dental anesthesia and in procedures involving the maxillary premolar region and maxillary sinus.