6 THE MENINGES OF THE BRAIN. 



arachnoid (Fig. 4) and seem to afford an outlet for the sub- 

 arachnoid fluid into the sinuses. They are said to make their 

 appearance about the tenth year and to be more numerous and 

 larger in the male sex. Some of them by absorption produce 

 depressions in the cranial bones called joveola granulares. 



The arteries which supply the dura are (i) The anterior 

 meningeal from the anterior ethmoidal branch of the ophthalmic. 

 (2) The middle meningeals, viz., the great and the small middle 

 meningeal from the internal maxillary, the meningeal branch 



Fig. 4. Coronal section showing falx cerebri, superior sagittal sinus and arachnoid 

 granulations. (Gordinier after Key and Retzius.) 



a. Subarachnoid space, b. Superior sagittal sinus, c. Arachnoid granulations (Pacchioni). 

 d. Dura mater, e. Falx cerebri. f. Anterior cerebral artery, g. Corpus callosum. 



of the lacrimal and of the internal carotid, and the meningeal 

 branch of the ascending pharyngeal which enters the middle 

 fossa of the cranium through the lacerate foramen. (3) The 

 posterior meningeal arteries, which rise from the ascending 

 pharyngeal, the occipital and the vertebral and are distributed 

 to the dura over the posterior cranial fossa. 



The great middle meningeal artery (arteria meningea media) 

 is much the largest and is most important (Fig. 5). It overlies 

 the motor and somaesthetic areas of the brain. Like the other 

 meningeal arteries it is usually accompanied by two veins. Ascend- 



