42 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



passes from this note!) to the posterior edge of the external 

 ^auditory meatus. 



The antcroinferior border is thick, and bevelled above con- 

 tinously with the upper border at the expense of the inner 

 surface, below at the expense of the outer all for articulation 

 with the great wing of the sphenoid. 



FIG. 7 



CNSOK FYMPANI 



Carotid en 

 Fenestra rotunda 



Pyramid! 



IOC. 



Eustachian tube. 



Carotid canal. 



Styloid process. 

 Aquzeductun Fallopii. 



Mnrrnir cell*. 



Section through the petrous and mastoid portions of the temporal bone, showing the 

 communication of the cavity of the tympanum with the mastoid antrum. 



The mastoid portion (teat-like) is rough for muscular attach- 

 ment, and prolonged down behind the auditory meatus as the 

 mastoid process. At the posterior border is the mcLstoid foramen, 

 sometimes foramina, transmitting veins to the lateral sinus 

 and a mastoid artery from the occipital; the foramen is incon- 

 stant, and may be in the occipital bone or in the mastooccipital 

 suture. On the inner side of the mastoid process is the digastric 

 fossa for attachment of the posterior belly of the digastric, 

 and internal to this is the sulcus occipitalis for lodgement of 

 the occipital artery. 



The internal surface shows the fossa sigmoidea, which is a 

 part of the sulcus for the lateral sinus; the mastoid foramen 

 opens into it. A section of the mastoid portion shows a number 



