124 APPLIED PHYSIOLOGY 



233. The senses. The cells of the body are continually 

 sending news of their own state to the spinal cord. The 

 brain feels the news only when it is very great in amount, 

 as when the body is hungry or thirsty or tired. 



The cells also send messages telling what is affecting 

 them from the outside. This news goes to the brain and 

 produces a feeling, while it only slightly affects the spinal 

 cord. We get news of the outside world by means of see- 

 ing, hearing, feeling, smelling, and tasting. 'These five 

 kinds of news are called the senses. 



234. Location of the senses. Feelings of sight are 

 brought to the cells of the brain under the lower and back 

 part of the head. Messages of sound, smell, and taste 

 reach the mind in the cells just above the ears. We feel 

 a touch or pain by means of the cells under the top part 

 of the head. This means that if the back part of the brain 

 is injured, we can no longer see. In the same way, an 

 injury to any part of the brain deprives us of the sense 

 which is located there. 



235. Motion. Besides feeling, we can also move our 

 bodies as we wish. The orders for moving are sent from 

 the brain down the spinal cord, and out along the nerves, 

 to the muscles. They cause the muscles to move the 

 body. That part of the brain under the top of the head 

 in front of the ears sends the orders for motion. If this 

 part of the brain is hurt, we cannot move so much as a 

 finger, even if we can feel and have a full knowledge of 

 what touches it. Each muscle has its own set of cells in 

 the brain. These do the same things in both man and 

 animals. 



236. Memory. When a cell of the brain receives a 

 message, it lays it away so that it can find it again. A 

 message stored away for use is a memory. We remember 



