[A histoanatomical study of the facial nerve and facial canal].

zontal segment and pyramidal segment, but it was small at the vertical segment. In infants, the rate was smaller than in adalts except for part of foramen stylomastoidea. 3. The wall of the facial canal was thinest on the side of tympanic cavity especially at the horizontal and pyramidal segment and thinest portion of the canal wall was 0.1 to 0.3mm thick on an average. On the side of the mastoid cavity, the canal wall was thiner than what had been reported in the previous studies. At the vertical segment, the thickness of the wall facing to the mastoid cavity was about 1mm. 4. The wall of the facial canal showed a disposition to be thin in those which had a good pneumatization of the mastoid cavity. 5. The facial canal is supplied by the R. petrosus of A. meningica media and also by A. stylomastoidea. Both arteries make an anastmosis at the pyramidal segment. The R. petrosus of A. meningica media occupied the tympanic cavity side of the canal and A. stylomastoidea, mastoid cavity side. 6. Dehiscences of the facial canal were found in 7 out of the 28 temporal bones. Most of the dehiscences were reconized above the oval window and the size of the dehiscence was largest there. The dehiscences were covered by the connective tissue and moucous membrane. The anther considered histologically that the dehiscences were due to disturbance of ossification of the canal wall. 7. The facial nerve is devided into 2 or 3 portions by the perineurium. This might suggest that the nerves in each portion innervate a specific facial muscles.