THE MENINGEAL VESSELS 



117 



in the first instance, produce any motor paralysis, but it will 

 lead to pressure on the higher auditory centres. These 

 effects, however, cannot be recognised owing to the accom- 

 panying loss of consciousness. 



FIG. 57. Lateral Aspect of Skull, showing the relations of important 

 structures to the surface. 



1. Zygomatic arch. 



2. Middle meningeal artery. 



3. Greater wing of sphenoid. 



4. Glabella. 



5. Temporal line. 



6. Anterior branch of middle meningeal 



artery. 



7. Central sulcus (of Rolando). 



8 Coronal suture. 



9 Lateral fissure, posterior ramus. 



10. Superior temporal sulcus. 



11. Posterior branch of middle meningeal 



artery. 



12. Line drawn from floor of orbit 



through centre of external acous- 

 tic meatus. 



13. External occipital protuberance. 



1 . Site for puncture of lateral ventricle. 



2 . Site for puncture of inferior horn of 



lateral ventricle.] 



The walls of the meningeal veins are very similar in 

 structure to the walls of the cranial blood sinuses, and they 

 consist of an endothelial layer and a slight amount of 

 supporting fibrous tissue. On this account they are easily 

 torn, and in most cases meningeal haemorrhage has its source in 

 the veins and not in the arteries. 



