• 1The maxillary nerve has been dissected throughout its course in representatives of the Prosimii (tree shrew, lemur, loris and galago); the Ceboidea (New World monkeys); the Cercopithecoidea (Old World monkeys), and the Hominoidea (chimpanzee, orang-utan and man).
  • 2The maxillary trunk gives off the zygomatic and superior dental nerves before splitting at a variable point into nasal and labial divisions. The first is distributed to the side and vestibule of the nose and supplies the rhinarium if present. The second is distributed to the mystical vibrissae (if present) and to the skin of the cheek and upper lip—some of its branches being faaciculated with twigs of the facial nerve.
  • 3In the Prosimii, where a rhinarium is associated with an uncomplicated facial musculature, the nasal division is the bigger. Relatively few fibres of the labial division are fasciculated with twigs of the seventh nerve.
  • 4In monkeys where the rhinarium has disappeared and the facial musculature has increased in complexity, the labial division is the bigger and more of its fibres are associated with twigs of the facial nerve. In certain New World monkeys (Lagothrix, Saimiri and Ateles) many of these presumably proprioceptive fibres travel via the zygomatico-facial nerve.
  • 5The further elaboration of the facial musculature in apes results in still more fibres being fasciculated with twigs of the seventh nerve, while in man, the trend continues further and the infraorbital plexus is more extensive than in any lower primate.