230 



MAMMALIAN ANATOMY 



medial to the fossa for the stapedius muscle. The anterior wall is not 

 clearly defined ; its inner part is behind the posterior wall of the 

 internal auditory meatus ; its outer part is the posterior wall of the 

 tensor tympani fossa. 



FIG. 162. 



External Ampulla. 



Aquxductus Fallopii.-., 



Superior Ampulla.- 



Wall between TENSOR TYMPAN 



Fossa and Vestibule. 



Posterior Ampulla. 



Terminal Whorl. 



Hamulus. . 



Scala Vestibuli. j 



External Semicircular Canal. 



Fossa for STAPEDIUS. 

 \-Posterior Semicircular Canal. 



External Semicircular Canal. 

 United Superior and Posterior Canals. 

 '-Vestibule. 



Scala Tympani of Cochlea. 



LEFT PETROUS. (INFERIOR SURFACE REMOVED.) (Enlarged Four Times.) 



In the roof of the vestibule, at its posterior inner part, is the open- 

 ing of the united non-ampullar ends of the superior and posterior 

 semicircular canals ; this opening is directed upward, backward, and 

 inward. Just anterior and medial to it is the small inner opening of 

 the aquseductus vestibuli. Behind and ventral to these openings is the 

 ampulla on the lower end of the posterior semicircular canal ; it is 



FIG. 163. 



Superior Ampulla. 



External Ampulla. 



FenestraOvaUn 



Cochlea. 



I'n it i<l Superior and Posterior 



>< iniriri'idur Canal*. 

 E.rtirnttl Siiiii<-ircn/(ir Cnnnl. 

 Posterior Ampulla. 

 Scala }'estibuli. 

 Fcnestra Kutiiiida. 



METAL CAST OF THE LEFT BONY LABYRINTH. LATERAL ASPECT. 



(Enlarged Four Times.) 



directed outward, backward, and upward. At the anterior lateral part 

 of the roof of the vestibule is the opening of the ampulla on the 

 upper end of the superior semicircular canal ; it is directed upward 

 and outward. Behind and below this ampulla is another which leads 



