The maxillary nerve, second division of the trigeminal nerve, is entirely sensory. It has been reported that drooling may occur later in the event of fracture of the zygoma in which hypesthesia prevails. The aim of the study is to elucidate additional detailed anatomy of the infraorbital plexus, consisting of the superior labial branch of the infraorbital nerve and facial nerve in the cheek. The authors dissected infraorbital nerves and facial nerves in 16 cadavers. Most terminals of the zygomatic branch of the facial nerve emerged from under the levator labii superiors and zygomatic muscle and infraorbital nerve. A hazardous zone of infraorbital plexus is found in a circle 36 mm in diameter. Its center is located 22 mm below the inferior orbital foramen. This hazardous zone of infraorbital plexus should be kept in mind when performing any procedures related to zygoma, maxilla, or deep cheek injuries.