File:An academic physiology and hygiene (1903) (14780828812).jpg

Identifier: academicphysio00bran (find matches)
Title: An academic physiology and hygiene ..
Year: 1903 (1900s)
Authors: Brands, Orestes M. (from old catalog) Van Gieson, Henry C., (from old catalog) joint author
Subjects: Hygiene Physiology
Publisher: Boston, B. H. Sanborn & co
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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tire brain.It consists of two hemispheres, the right and the left, andis composed of a thick layer of gray matter surroundingwhite, fibrous nerve-substance. The surface of the brain(the gray matter) is drawn up into numerous irregularfolds or convolutions, by which its area is greatly in-creased. Beneath the layer of gray matter are foundinterlacing, white fibres, so intimately combined that theanatomists knife is unable to separate them completely,In parts of the cerebrum these fibres cross and recross,and thus the parts of the brain are connected. It is from 236 ACADEMIC PHYSIOLOGY. the crossing of these fibres in the centre of the brain thatinjuries upon its left side are manifested by paralysis onthe right side of the body, and vice-versa. Wherever maybe the exact seat of the motor principle, the brain exercisesa cross-action on the muscles ; that is, the left hemisphereinduces the movements of the right side of the body, andthe right hemisphere those of the left. The white fibres
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-CE CER Fig. 45. EXPLANATION. This figure represents the left half of the brain. CE, the cerebrum; CER, the cere-bellum; MO, the medulla oblongata ; OP, optic nervel SC, spinal cord; AV, arbor vitae. of the brain also pass down to the spinal cord and conductthe impulses of motion. Other fibres coming up from thecord convey sensory impulses to the gray matter. Thusthere is seen to be a circuit as in a telegraphic system —messages being sent from and other messages being sentto headquarters. THE NERVOUS SYSTEM. 237 13. The cerebrum is the principal seat of intelligence,the will, the emotions, sensation, and voluntary motion.It would be beyond the scope of this volume to enter intoa detail of the functions ascribed to the various parts ofthe cerebrum ; but brief mention of the matter will openthe way to future research, if that is desired. 14. Ferrier has mapped out areas on the brain, each ofwhich, as proven by experiment upon animals, is the seatof distinctive nerve-impulses.1 Examin

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