22 ANATOMY AND PHYSIOLOGY 



The inner surface of this bone has broad grooves for the transverse sinuses 

 (lateral sinuses); also one for the sagittal sinus (superior longitudinal sinus). 



Temporal bones (ossa temporales). Right and left; situated 

 at the sides and base of the skull. (See Figs. 12 and 14.) 



Each temporal bone consists of four portions the squamous, 

 the mastoid, the petrous, and the tympanic. 



The squamous portion (squama temporalis) is flat, and presents 

 the zygomatic process in the form of a ridge running forward in front 

 of the ear to the cheek. Below the beginning of this process is the 

 canal leading into the ear and called the external auditory meatus; 



FIG. 14. PARIETAL, TEMPORAL, AND SPHENOID BONES; POSTERIOR ASPECT. 

 i, Body of sphenoid bone; 2, 2, greater wing and squamous portion of sphenoid 

 bone; 3, 3, parietal bones; 4, 4, mastoid process of temporal bones. (Sappey.) 

 The occipital bone occupies the space outlined by these bones posteriorly. 



just in front of that is the mandibular fossa, where the lower jaw- 

 bone, or mandible, is joined to the temporal bone (Fig. 12). 



The mastoid portion forms the prominence behind the ear and 

 terminates in the mastoid process, which contains a number of 

 small cavities, the mastoid cells. They all communicate with 

 the middle ear, and mastoid disease may therefore follow an 

 infection of the middle ear. 



The inner surface of this portion shows the sigmoid groove for the transverse 

 sinus. 



