The mandibular or third division of the trigeminal nerve is the largest of the three divisions. It is considered a mixed nerve. That is, like the ophthalmic and maxillary divisions, the mandibular conveys afferent fibers. But unlike the former two divisions, the mandibular also contains motor or efferent fibers to the muscles of mastication, the mylohyoid and anterior digastric muscles, and the tensor veli palatini and tensor tympani muscles. So intimately associated with dentistry, the mandibular nerve has also been termed the dental nerve by anatomists in the past. This extensive and complicated division of the trigeminal nerve can cause confusion to both patient and doctor. Pain is often referred within its branches and even into other trigeminal divisions, chiefly the maxillary. This fourth and last article about the trigeminal nerve will present in detail the mandibular division.