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A MANUAL OF ANATOMY 



meatus there is a narrow fissure, overhung by a thin scale of bone, 

 called the aqueductus vestibuli, which contains a small artery and 

 vein, and the ductus endolymphaticus. Close to the superior border, 

 about midway between the opening of the internal auditory meatus 

 and the aqueductus vestibuli, there is a depression containing a 

 small opening, known as the fossa subarcuata, which represents 

 the floccular fossa of early life. 



The inferior surface appears on the exterior of the base of the 

 skull. Near the apex there is a large rough surface which gives 

 origin to fibres of the levator palati, and behind this a circular 

 opening, called the carotid foramen, which is the inlet to the carotid 



Mastoid 

 Antrum 



Pyramid, with Opening for Stapedius 



Fenestra Ovale 

 Aqueduct of Fallopius at Hiatus Fallopii 



Gasserian Depression , 



> Mastoid Cells 



Outlet of Carotid Canal 



Promontory ' ^ \ 

 Fenestra Rotunda r 



Sinus Tympani 



Outlet of Aqueduct of Fallopius 

 at Stylo-mastoid Foramen 



Fig. 50. — Section through the Petrous and Mastoid Portions of the 

 Temporal Bone, showing the Tympanum and M.\stoid Cells. 



canal. This canal, which transmits the internal carotid artery 

 and the carotid sympathetic plexus, passes at first vertically 

 upwards, and then, bending at a right angle, it passes horizontally 

 forwards and inwards, to open at the apex, below the Gasserian 

 depression, into the foramen lacerum medium. On the posterior 

 wall of the vertical portion of the canal is a minute foramen for the 

 tympanic branch of the carotid sympathetic plexus and tympanic 

 branch of the internal carotid artery. Behind the carotid foramen 

 is the jugular fossa, which, with the jugular notch of the occipital, 

 forms the jugular foramen. On the outer wall of this fossa, near 

 the root of the styloid process, there is the opening of the auricular 

 canaliculus for the auricular branch (Arnold's nerve) of the pneumo- 

 gastric. On the carotid ridge, between the carotid foramen and 



