THE CRANIUM. 17 



culate with the superficial and with the occipital and 

 posterior auricular which supply the hinder part of this 

 regipn. The arrangement of the several aponeuroses in 

 this region determines the course taken by purulent col- 

 lections ; thus, supposing the matter to be deepseated, it 

 will make its way into the zygomatic fossa, and when 

 superficial it will be limited by the tough aponeurosis 

 already mentioned. The posterior part of this region, 

 which contains the mastoid process of the temporal bone, 

 is the seat of an operation proposed for the opening of 

 the mastoid cells with the object of giving vent to matter 

 pent up in them, should it not find its way either by the 

 Eustachian tube or through the external auditory meatus. 

 Fractures in this region are frequently complicated with 

 laceration of the middle rneningeal artery, which runs 

 over the internal aspect of the cranium. 



This region contains numerous lymphatic ganglia, 

 which become remarkably indurated in constitutional 

 syphilis. 



The structures divided in cutting down upon the bone in 

 the temporo-parietal region are the skin, subcutaneous 

 fascia, epicranial aponeurosis, superficial temporal apon- 

 eurosis, deep temporal aponeurosis, temporalis muscle 

 and tendon, with the superficial and deep temporal ves- 

 sels, nerves, and lymphatics. 



SURGICAL ANATOMY OF THE CKANIUM. 



The structure of the cranial bones forming the vault 

 of the skull consists of three layers ; an outer, formed of 

 tough compact tissue; an intermediate, the diploe, soft 

 and spongy, having the diploic veins ramifying in its 

 substance ; and an inner, hard and brittle. These di- 

 ploic veins, after injury followed by suppuration, are lia- 



