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On the Diseases and Derangements of the Nervous System
On the Diseases and Derangements of the Nervous System Author:Marshall Hall Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Section II.? The Physiology of the Cerebral System. 105. I shall be brief in my observations on the physiology of the cerebral system; and my object, in the o... more »bservations which I do make, will be principally to point out the perfect distinctness of this and the true spinal system. 106. The physiology of the cerebral system comprises sensation in all its forms, perception, judgment, volition, and voluntary motion. 107. The senses, I need scarcely say, are the smell, the sight, the hearing, the taste, the touch ; they convey to the mind all that we know of the external world. Perception is derived from these. Judgment is a purely mental act. So is volition ; and of this, voluntary motion is a frequent result. The motions which result from sensation generally imply volition ; but as volition may exist without any previous sensation, the voluntary motions frequently are, and may be at any time, spontaneous, as I have already stated, § 7. 108. It is almost unnecessary to advert to the scries of operations in what appears to be the very simple process of voluntary motion consequent on sensation. I may, however, briefly state that that sensation, or some effect of the impression which produces it, must be conveyed by an appropriate nerve uninterruptedly to the cerebrum,?to the i|x); and that thence the act of volition must act through a voluntary nerve, equally uninterrupted in its course, from the cerebrum to the muscle or muscles to be moved. 109. Thus we have a nervous arch, of which the cerebrum is the key-stone. Such arches are displayed in the Table, at p. 17?18, and in Plate II, Jig. 1. 110. There is an affection of the mind to which I have briefly adverted above ; viz. emotion ; and this may be excited by a sensation : it may also immediately issue in motion. But...« less