. The Ontario public school hygiene . indifferent regions of the body. The nerve-fibres of the nervous system have oftenbeen likened to the separate wires of a telephone ortelegraph cable. Just as each separate wire in atelephone cable can transmit a separate message, soeach separate thread, or fibre, in a bundle of nervescarries its own message to or from the brain, or to orfrom the spinal cord. By a study of certain diseases of the human brainas seen among patients in a hospital for the insane,and by experiments upon the brain of some of thelower animals, physiologists have discovered that c
. The Ontario public school hygiene . indifferent regions of the body. The nerve-fibres of the nervous system have oftenbeen likened to the separate wires of a telephone ortelegraph cable. Just as each separate wire in atelephone cable can transmit a separate message, soeach separate thread, or fibre, in a bundle of nervescarries its own message to or from the brain, or to orfrom the spinal cord. By a study of certain diseases of the human brainas seen among patients in a hospital for the insane,and by experiments upon the brain of some of thelower animals, physiologists have discovered that certain 198 PUBLIC SCHOOL HYGIENE parts of the gray matter are connected with the specialsenses,—sight, hearing, taste, touch and smell. By similar methods of study it has been discoveredthat the voluntary movements of the body are allcontrolled from other areas of the gray matter. Inother words, the surface of each half of the brainhas been mapped out into areas, some of which areconcerned with receiving messages from the different. SMELLIWqANOTASTIIVCjN / OW INNER SURFACE t-^ Of THIS L06E J Figure 81.—Side of the cerebrum showing- areas connected with the senses or sensoryareas, and the areas connected with movement, that is, the Motor Areas. Thedarlt lines denote the fissures in the gray matter. senses, and others with sending out messages to themuscles which control the voluntary movements of theeyes, head, trunk, and limbs. The areas which are concerned with voluntary move-ments, that is, the motor areas, are, roughly speaking,triangular in shape for each half of the brain. The basesof each pair of triangles are upon the mid-line of the brain,and the other two sides extend downwards to pointsabout half-way between the ear and the eye at each side. STRUCTURE OF THE NERVOUS SYSTEM 199 From the gray matter of these areas, nerve-fibresextend down through the brain and run out along withthe large nerves of the brain or spinal cord, endingfinally in the voluntary muscles of t
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