reported that the middle superior alveolar
nerve followed the classical description in only 30% of
examined cases whilst the majority of middle branch entered
the formation of a nerve plexus that supplied the teeth. When
the middle branch was absent, the innervation of the premolar
teeth may be provided by secondary branches of the anterior
superior alveolar nerve, by the posterior superior alveolar
nerve or by a nervous plexus between these two nerves. Even if
this situation is not easily detectable, this variation should be
considered during anaesthetic procedures.