Bonos of the Cranium. 



15 



15, Left Temporal Bone, Os temporum, from the inner side. 



The squamous portion shows on its internal surface strong 

 eminences and depressions for the cerebral convolutions, Impressiones 

 digitatae and Juga cerebralia, and 2 grooves (for the middle meningeal 

 artery and vein). 



The petrous portion has 3 surfaces (posterior, superior and 

 inferior) and 3 borders (superior, anterior and posterior). 



On the smallest posterior surface the oval orifice of the Mcatus 

 auditorius interims (Mcatus acusticus interims), 3'" externally of this, that of the 

 Aquaeductus vestibuli. The largest superior surface is separated from 

 the squamous portion by the Sutura (Fissura) pctroso-squamosa ; it has an 

 eminence for the superior semicircular canal, Eminentia canalis scinicircu- 

 laris sitpzrioris. Near the summit of the pyramid the inner opening 

 of the carotid canal, Canalis caroticus, from which a groove (Scnucanalis 

 Nervl Vidiani) leads externally to a small foramen, the Hiatus (Apertura 

 spuria) canalis Fallopiae. In this groove opens the small Canaliculus pctrosus. 



The u p p e r b o r d c r of the petrous portion is grooved 

 for the superior petrosal sinus, Sulcus petrosus superior; the posterior 

 border excavated by the Tncisura juyidaris. 



The mastoid portion shows on its inner surface a deep groove, 

 Fossa sigmoidea (for Ihe Sinus transversus) ; a foramen, not always present, 

 the Foramen mastoideum (for an Emissarium Santorini), leads from this 

 groove to the external surface of the bone. 



