THE SKULL THE CRANIUM 



235 



The cochlea can be clearly shown by means of a section which 

 divides the petrous obliquely, passing through the internal auditory 

 ineatus, the fenestra rotunda, and the superior border in front of the 



FIG. 169. 



Rim of Fenestra Ovalis. 



Scala Vestibuli. 

 Lamina Spiralis, 



Scala Vestibuli. 

 Scala Tympani. 



Scala Vestibuli. \ 



Rim of Fenestra Ro- 

 tunda. 



Scala Tympani. 



Aquseductus Cochlex. 

 Spiral Cribriform Tract. 



Internal Auditory 



Meatus. 



Scala Tympani. 



OBLIQUE SECTION THROUGH LEFT PETROUS, SHOWING COCHLEA. 

 INFERIOR ASPECT. (Enlarged Four Times.) 



hiatus Fallopii (Fig. 169). Such a section lies almost in the horizontal 

 plane of the skull. The superior aspect shows no traces of the vesti- 

 bule. 



FIG. 170. 



Tentorium of Parietal. - 



Aquxductus Fallopii.^ 

 Fovea Hemisph&rica.. 



Rim of Fenestra Ovalis.* 



TENSOR TYMPANI FOSStt. ._ 



Scala Vestibuli.^ 



Promontory. 

 Alisphenoid.^ 



Ectotympanic 



Superior Ampulla. 



Fovea Hemi-elliptica. 



Superior and Posterior Semicircular Canals. 



Medial Wall of Ves- 

 tibule. 



External Semicircular 

 Canal. 



. Posterior Ampulla. 



Lamina Spiralis. 

 Scala Tympani. 

 ..Paroccipital Process. 



Entotympanic Cavity. 



LONGITUDINAL VERTICAL SECTION THROUGH LEFT TEMPORAL. LATERAL ASPECT. 



(Enlarged Four Times.) 



The exact relation of the parts of the bony labyrinth to the planes 

 of the skull can be established only by sections made in those planes. 



