Nerve · Head

Posterior superior alveolar nerve

Nervi alveolares superiores posteriores

The nerve of the upper back teeth. Unlike its two partners it branches off the maxillary nerve early, in the pterygopalatine fossa, before that nerve turns into the orbit — so it never enters the infraorbital canal at all. It runs down across the back surface of the maxilla, gives a twig to the gum on the cheek side, then dips into small foramina and travels inside the bony wall of the maxillary sinus to reach the molars and the sinus lining, joining the superior dental plexus. Because it hugs the rounded back of the upper jaw, its course lies directly behind the last molar — the part of the upper arch a reader can reach with a fingertip.