The maxillary nerve gives sensory innervation to all structures in and around the maxillary bone and the midfacial region including the skin of the midfacial regions, the lower eyelid, side of nose, and upper lip; the mucous membrane of the nasopharynx, maxillary sinus, soft palate, palatine tonsil, roof of the mouth, the maxillary gingivae, and maxillary teeth. This vast and complex division of the trigeminal nerve is intimately associated with many sources of orofacial pain, often mimicking maxillary sinus and/or temporomandibular joint involvement. For those who choose to treat patients suffering with orofacial pain and temporomandibular disorders, knowledge of this nerve must be second nature. Just providing the difficult services of a general dental practice should be stimulus enough to understand this trigeminal division, but if one hopes to correctly diagnose and treat orofacial pain disorders, dedication to understanding this nerve cannot be overstated. In this, the third of a four part series of articles concerning the trigeminal nerve, the second or maxillary division will be described and discussed in detail.