Head and Neck. 411 



It must not be forgotten that a fracture involving the 

 petrous portion of the temporal bone may permit blood to 

 be effused into the tympanum and thence, passing into the 

 pharnyx through the Eustachian tube, be swallowed. 



(3) Paralysis of Nerves. This will be considered 

 later on. 



(4) Escape of cerebro-spinal fluid from the ear and 

 nose. In the case of the ear it would be necessary in 

 order to allow the fluid to escape, that the membrana tym- 

 pani should be ruptured and that the tympanum should 

 be opened up, and further, that the fracture should tra- 

 verse the internal auditory meatus, and, lastly, that the 

 meningeal sheath around the auditory and the facial 

 nerves should be torn (the cerebro-spinal fluid lies within 

 this sheath), while, in the case of the nose, the dura mater 

 must be torn, and, in addition, the orbital plates fractured. 



Meningeal Arteries. These vessels are for the 

 purpose of nourishing the dura mater and the bones of the 

 skull, especially the latter, and are derived as follows, viz. : 

 Those in the anterior fossa are from the anterior and the 

 posterior ethmoids ; those in the middle fossa are from the 

 ascending pharyngeal, the internal carotid and the internal 

 maxillary; while those belonging to the posterior fossa 

 are from the occipital, the ascending pharyngeal and the 

 vertebral. The chief one of these meningeal vessels is 

 the middle meningeal artery, which arises from the inter- 

 nal maxillary and ascends to the interior of the cranium 

 through the foramen spinosum, and then, after passing up 

 the greater wing of the sphenoid, divides into two 

 branches anterior and posterior. The anterior branch 

 of this middle meningeal artery is lodged in a depression 

 on the greater wing of the sphenoid and on the anterior 

 portion of the parietal (often the groove in the parietal is 

 converted into a canal), and terminates near the superior 



