416 Anatomy Applied to Medicine and Surgery. 



tion of the superior longitudinal sinus with the venous 

 system of the nose by means of a small vein which passes 

 through the foramen caecum ; or, it may be seen in infect- 

 ive periostitis, the result of dental caries ; or in suppurative 

 tonsillitis ; or retro-pharyngeal abscess, etc., and in these 

 instances, the infection spreads to the cavernous sinus 

 through the pterygoid plexus of veins. It may result 

 from infective processes which develop in the tympanum 

 and then pass along the small emissary veins that connect 

 this cavity and the petrosal bone with the lateral (sig- 

 moid) sinus ; or, it may develop from inflammatory condi- 

 tions situated in front of the ear and spreading along the 

 superficial temporal vein to the longitudinal sinus through 

 the parietal foramen; or, from those situated behind the 

 ear and passing to the lateral sinus through the mastoid 

 foramen, or, from deep-seated abscesses in the posterior 

 part of the neck affecting the occipital sinus through the 

 anterior condyloid foramen, or the lateral sinus, through 

 the posterior condyloid foramen. Lastly, osteomyelitis 

 affecting the bones of the skull may induce infective dis- 

 ease of the sinuses, since, as already mentioned, some of 

 the diploic veins open into these sinuses. Conversely, in 

 sinus phlebitis, there may result distention of these emis- 

 sary veins, as seen when the cavernous sinus is affected. 

 Here there may be swelling of the eyelids, or of the con- 

 junctiva, etc., or, if the longitudinal be affected, epistaxis 

 may result, or cedema may occur over the temporal re- 

 gion through the parietal foramen ; or there may be swell- 

 ing over the mastoid, through the mastoid foramen, when 

 the lateral sinus is inflamed. 



Landmarks for the middle meningeal artery. This 

 vessel begins on a level with a point half an inch in front of 

 the external auditory meatus, and from this point, the 

 posterior branch runs towards the lambda, passing about 



