16 



Bones of the Cranium. 



Semicanal. tensor, tympani 



Tulta JEustachii 

 M. Levator palati 

 caroticuA- 



Proc.styloideus 



Canalicvl. mastcid. 

 Canaliculi cartft.tym,pani.ci I 



Aquaeditctus codileae 



10. Left Temporal Bone, Os temporum, from below. 



The inferior surface of the petrous portion forms at its 

 external part a small plate of bone, Os tympanicum, which surrounds 

 the Jleatus audltorlus cxternus inferiorly and anteriorly, and is separated 

 from the glenoid fossa of the squamous portion by the Glaserian fissure, 

 Fissura Glaserl (Fig. 14). 



Passing from within outward we have : the Foramen stylo-mastoidmm, 

 below the external auditory meatus (termination of the Aquaeductus Fallopii) 

 the Processus styloideus ; the Fossa jugular is with the small orifice of the Canali- 

 culus mastoideus. - - Near the jugular fossa the lower opening of the Cancdis 

 caroticus, and above this two small canals, Canalicidi carotico-tympanici (to 

 the tympanic canty) ; toward the posterior border the triangular orifice 

 of the Aquaeductus cochleae. Between the Incisura jugular is and the lower 

 opening of the carotid canal lies the Fossula pctrosa, with the origin 

 of the Canalicidus tynrpanicus. 



At the shortest anterior border of the petrous portion 

 (at its outer end), lies an opening divided into 2 halves by a thin 

 plate of bone ; the upper smaller one is the commencement of the Seml- 

 canalis tcnsoris tympani, the lower one the opening of the Tuba Eustachii. 



