68 



THE SKULL AND THE BONES OF THE SKULL 



Superior semicircular canal Canalis semicircularis superior 

 Anterior surface of petrous portion Facies anterior pyramidis 



Vestibule of the labyrinth 

 Vestibulum labyrinth! 

 Geniculum of the aqueduct of Fallopius - 



Geniculum canalis facialis 



Oochleariform process 



Processus cochleariformis 



Cochlea 



Cochlea 



Carotid canal ' 



Canalis caroticus 



Jugular fossa 

 Fossa jugularis 



External semicircular canal 



/Canalis semicircularis lateralis 



Superior border ol the petrous bone 



'Angulus superior pyramidis 



^Posterior semicircular canal 

 Canalis semicircularis posterior 



Posterior surface of the petrous bone 



Facies posterior pyramidis 

 Promontory 



Promontorium 

 ~"~ Aqueduct of Fallopius 

 Canalis facialis 



- Fossula of the fenestra rotunda, or fossula rotunda 



Fossula fenestra; cochleae 



Fenestra ovalis 



Fenestra vestibuli 



FIG. 139. THE BONY LABYRINTH, LABYRINTHUS OSSEUS, SHOWN IN THE LEFT PETROUS PORTION. 

 SEEN OBLIQUELY FROM IN FRONT AND BELOW. THE OSSEOUS SEMICIRCULAR CANALS AND 

 ALSO THE CANAL OF THE COCHLEA HAVE BEEN PARTLY OPENED. THE RELATIONS BETWEEN 

 THE AQUEDUCT OF FALLOPIUS AND THE OSSEOUS LABYRINTH ARE CLEARLY SHOWN. 



Area cribrosa superior (transmits the filaments 



of the superior division of the auditory nerve) 



Area vestibularis superior 



A>M cribrosa media (transmits the nerve 



to the saccule) 

 Area vestibularis inferior 



*Area of the cochlea 1 - 

 Area cochleae 1 



External orifice of the aqueduct of the vestibule- 

 Apertura externa aquaeductus vestibuli 



Foramen singulare (for the nerve to the posterior 



semicircular canal) 

 Foramen singulare 



Aqueduct of Fallopius 



/Canalis facialis 



j ^,.*Area of the facial nerve 1 



jgfei *Area n. faciali 



Transverse crest, or crista falciformis 



Crista transversa 



Tractus spiralis foraminulentus (the 

 foramina of which transmit the fila- 

 ments of the cochlear division of the 

 auditory nerve) 1 



Tractus spiralis foraminosus 



Internal auditory meattis 



Meatus acusticus internus 



Internal auditory aperature 

 Porus acusticus internus 



1 The helicoid depression of the tractus spiralis foraminulentus corresponds with the base of the cochlea, and 

 at the centre of the helix is the foramen centrale cochleae, the orifice of the central canal of the modiolus. On 

 the significance of this term Area of the Cochlea, see also note 5: ", p. 956)1, in the Appendix to Part VI. ; and on the 

 significance of the term Area of the Facial Nerve, see note lss on the same page. 



FIG. 140. THE INTERNAL AUDITORY MEATUS, MEATUS ACUSTICUS INTERNUS, EXPOSED FROM 

 ABOVE BY THE REMOVAL OF A RIGHT-ANGLED WEDGE FROM THE PETROUS PORTION OF 

 THE LEFT TEMPORAL BONE, DISPLAYING THE FUNDUS OF THE INTERNAL AUDITORY 

 MEATUS, OR RENIFORM FOSSA. DIVIDED BY THE TRANSVERSE CREST, OR -CRISTA FALCI- 

 FORMIS, INTO SUPERIOR AND INFERIOR i<oss,. SEEN FROM BEHIND AND ABOVE. 



Os temporale Temporal bone. 



