CHAPTEE XI. 



DISEASES OF THE NEETOUS SYSTEM. 



The nervous system consists of the brain, which is lodged in 

 the cavity of the skull (cranium) ; the spinal cord, lodged in 

 the cavity of the vertebral chain ; and numerous little white 

 cords, called nerves, which are given out from the brain and 

 spinal cord, and distributed to the different parts of the 

 body, especially those parts endowed with sensibility, and 

 under the control of the will. Besides this system of 

 nerves, there is another set, independent of the cerebro- 

 spinal axis, called the sympathetic or ganglionic system, 

 which supply the organs of nutrition and other viscera, 

 blood-vessels, &c. It consists of numerous smaU centres, 

 called ganglia, extending in two great chains from the head to 

 the tail, on each side of the bodies of the vertebrse, closely 

 associated with ^he other system by intricate communication. 



INFLAMMATION OF THE BEAIN (PHEENITIS.) 



Phrenitis is not a very common disease, though the sub- 

 stance of the brain itself, or, a§ is more commonly the yase, 

 its membranes or coverings become inflamed. It has received 

 various appellations, such as mad staggers, sleepy stag- 

 gers, &c. 



Causes. — The causes are not thoroughly understood. In- 

 juries to the skull, metastasis, or the transferfiice of inflam- 



