In all the cases of fractured base which have come under my observation I have never seen the foramen rotundum implicated, and in one case only was the foramen ovale involved. In certain rare instances, a fracture, passing in the antero-posterior direction, may cut across the apex of the petrous bone in close relation to the cavum Meckelii--the bed of the Gasserian ganglion--in which case all three terminal divisions of the fifth nerve may suffer. Thus, a case was reported by Lee in 1853 in which, seven weeks after the accident, the following symptoms were present:--anæsthesia of the left face and forehead, anterior two-thirds of tongue, and left nostril, together with weakness of the left masticating muscles, and an opaque left cornea. _The sixth nerve._ The sixth nerve may be involved either by itself or in conjunction with other cranial nerves. In the latter case the paresis is due to blood extravasated in the sphenoidal fissure or in the orbital cavity. In the former case the nerve is injured where it grooves the lateral aspect of the dorsum ephipii, a process frequently fractured in lesions of the middle fossa. Fractures tend to pass obliquely across this process, one nerve usually escaping. The prognosis as to functional recovery is very problematical. _The seventh and eighth nerves._ There can be no doubt that the seventh nerve, on account of its complicated intrapetrous course, is more frequently involved than any other cranial nerve. Köhler records 22 cases in 48 middle fossa fractures. My own experience coincides closely with Köhler’s, facial paresis or paralysis being noted in nearly 50 per cent. cases of middle fossa fracture. The question of facial nerve implication is so intimately associated with involvement of the eighth nerve that the two subjects must be considered together. Thus, cases may be classified as follows:-- 1. Cases of paresis of the facial nerve with a variable degree of deafness. 2. Cases of complete facial paralysis with complete deafness. The greater number of middle fossa fractures involve the middle and external ears, as is evidenced, amongst other symptoms, by hæmorrhage from the ear. Some degree of facial paralysis is frequently existent, not always evident at first sight, but requiring careful examination and comparison between the two sides of the face. The fracture involves both roof and floor of the external ear and passes inwards towards the junction of anterior and inner walls of the middle ear, the membrana tympani undergoing a variable degree of destruction whilst the ossicles may also be injured. Thence, the fracture passes inwards towards the petro-sphenoidal suture in such a manner that the geniculate ganglion of the facial nerve is exposed and laid bare on the anterior aspect of the posterior portion of the skull.