. Psychology and the school. h of anervous impulse (consisting of a system of intercon-nected neurones) is sometimes referred to as a sensori-motor path or arc. It is called sensory because it hasits origin in a sense-organ (eye, ear, skin, and so forth).It is called motor because it ends in a muscle and isconcerned in the movement of the muscle. The hyphenindicates that the entire structure from beginning toend is in reality one mechanism and functions in aunitary way. Gray matter. — In many parts of the nervous sys-tem the cell-bodies are grouped closely together, giv-ing these parts a chara
. Psychology and the school. h of anervous impulse (consisting of a system of intercon-nected neurones) is sometimes referred to as a sensori-motor path or arc. It is called sensory because it hasits origin in a sense-organ (eye, ear, skin, and so forth).It is called motor because it ends in a muscle and isconcerned in the movement of the muscle. The hyphenindicates that the entire structure from beginning toend is in reality one mechanism and functions in aunitary way. Gray matter. — In many parts of the nervous sys-tem the cell-bodies are grouped closely together, giv-ing these parts a characteristic grayish fibers as are present here are very short, so thatthe bulk of the material is composed of matter is found especially in the outside portionof the cerebrum (known as the cortex) and in the in-side portion of the spinal cord. The cortex in thehuman cerebrum, although only an eighth to a quar-ter of an inch thick, is extremely complex, as shownin Fig. 7. THE NERVOUS SYSTEM 25. Fig. 7. A section of the cerebral cortex showing its extreme com-plexity. (From Thorndikes Psychology, by permission of the author.) 26 PSYCHOLOGY AND THE SCHOOL White matter. — The fibers of the various neuronesalso are grouped together to a large extent, and makeup the white matter of the nervous system. The whitematter forms the greater bulk of both the cerebrum andthe other structures in the brain that lie below thecerebrum. It forms also the outer portion of the spinalcord. The nerves shown in Fig. 4, as well as the whitematter of the central nervous system, are composed ofbundles of fibers. It must be remembered that no fiberis ever detached, but each forms a part of some neuronethe cell-body of which lies more or less distant from it. Types of sensori-motor arcs. — For the purpose ofour study the nervous system may be regarded asbeing made up of two types of sensori-motor arcs: (1)a relatively simple type in which nervous impulses donot pass to
Size: 1156px × 2161px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1921
