

THE TEMPORAL BONE 



141 



tympani nerve passes through a canal (canal of Huguier), separated from the an- 

 terior edge of the petrotympanic fissure by a thin scale of bone and situated on 

 the lateral side of the auditory tube, in the retiring angle between the squama 

 and the petrous portion of the temporal. 



The internal surface of the squama (Fig. 138) is concave; it presents depressions 

 corresponding to the convolutions of the temporal lobe of the brain, and grooves 

 for the branches of the middle meningeal vessels. 



Borders. The superior border is thin, and bevelled at the expense of the internal 

 table, so as to overlap the squamous. border of the parietal bone, forming with 

 it the squamosal suture. Posteriorly, the superior border forms an angle, the 

 parietal notch, with the mastoid portion of the bone. The antero-inferior border 

 is thick, serrated, and bevelled at the expense of the inner table above and of 

 the outer below, for articulation with the great wing of the sphenoid. 



Mastoid Portion (pars mastoidea). The mastoid portion forms the posterior 

 part of the bone. 



Tympanic antrum 



Tegmen tympani 



Prominence of lateral semicircular canal 

 Prominence of facial canal 

 Fenestra vestibuli 



Bristle in semicanal for Tensor tympani 

 Septum canalis muscidotubarii 



Bristle in hiatus of facial canal 







Carotid canal 



Bony part of auditory tube 

 Promontory 

 Bristle in pyramid 

 Fenestra cochleae 



Sidcus tympanicus 



Mastoid cells Bristk in stylomastoid foramen 

 FIQ. 139. Coronal section of right temporal bone. 



Surfaces. Its outer surface (Fig. 137) is rough, and gives attachment to the 

 Occipitalis and Auricularis posterior. It is perforated by numerous foramina; one 

 of these, of large size, situated near the posterior border, is termed the mastoid 

 foramen; it transmits a vein to the transverse sinus and a small branch of the occipi- 

 tal artery to the dura mater. The position and size of this foramen are very 

 variable; it is not always present; sometimes it is situated in the occipital bone, 

 >r in the suture between the temporal and the occipital. The mastoid portion is 

 continued below into a conical projection, the mastoid process, the size and form 

 of which vary somew T hat; it is larger in the male than in the female. This process 

 serves for the attachment of the Sternocleidomastoideus, Splenius capitis, and 

 Longissimus capitis. On the medial side of the process is a deep groove, the 

 mastoid notch (digastric fossa), for the attachment of the Digastricus; medial to 

 this is a shallow furrow, the occipital groove, which lodges the occipital artery. 





