CHAP. IX. &c. CHAPTER IX. THE NERVOUS FUNCTION-THE EXTERNAL SENSES, &C.-THE PASSIONS, Section I. Subjects of this Chapter, and proposed Arrangement. Section II. Of the Nervous Function and its Organs in general. Section III. Of the External Senses and their Organs. Section IV. Of the Passions and Emo- Section V. Of the Mind and Intellectual SECTION I.-SUBJECTS OF THIS CHAPTER AND PROPOSED ARRANGEMENT. The sub jects of this The Nervous Function; the External Senses; the Passions, Emotions chapter and Affections; the Mind or Intellectual Faculties; and whatever relates and proto Conscience and the Soul, as pre-eminently raising us above the brute posed arcreation, command our utmost attention, whether as regards the Healthy rangement. or the Diseased state. Without the former man would be a mere automaton, devoid of sensation and motion; without the mind, he would be bereft of all those high enjoyments with which he has been endowed beyond the mere sensual gratification of animals; whilst the monitions of Conscience, the conviction that our Souls are immortal, and that life here is but a probationary state, preparatory to life everlasting, excite and stimulate us to virtuous actions, and restrain us from evil, far more powerfully than mere moral considerations; all verify "that God created man in his own image."(a) These are interesting not only philosophically, but practically, since it is well established, that although some diseases may originate in the vascular system, yet more frequently they are attributable to some deviation from the due performance of the Nervous Function, and are greatly influenced by the passions, mental faculties, and still more by a troubled conscience.(b) Upon the state of the Brain and the Nerves depends the extent of our mental faculties, the degree of enjoyment of the several senses, our temperament, whether tonic or deviating into sanguine, phlegmatic, choleric, melancholic, or nervous, and our tempers.(c) The nerves, which arise partly from the brain and partly from its spinal continuation, are distributed by minute branches to every sensible part of the body, and constitute the immediate organs of two principal functions, Sensation and Volition. They convey, with the rapidity of electricity, impressions made upon any part of the body to the sensorium commune of the brain, and from that organ they transmit the (a) Genesis, chap. i.; and see Shakspeare: Hamlet, act ii. sc. 2: "How noble in reason! How infinite in faculties! in form and moving how express and admirable! In action how like an angel! In apprehension how like a God! The beauty of the world! The paragon of animals!" El. Blum. 544. We might add with Milton, in his description of Eve and woman, "Grace was in every step, Heaven in her (b) Mason on Self-Knowledge; Cogan (c) As to these, see ante, 49 to 51; and post. CHAP. IX. nervous influence to every sensible part of the body. The important subSECT. I. jects of this chapter will therefore principally be, the Nervous Function; the NERVOUS Several External Senses; the Passions, Emotions and Affections; and the FUNCTION, Mind or Intellectual Faculties; with some examination of Conscience and &c. the Soul. The organs and parts from which these spring, or where they are supposed to be situate, with their supporting or protecting organs or parts, will also be necessarily considered. Pursuing the same arrangement as adopted in the preceding parts, we will first examine the organs of each function, with some explanatory plates, and then proceed to the functions themselves. First. Defi nition and enumera tion of all SECTION II.-THE NERVOUS FUNCTION AND ITS ORGANS IN GENERAL. First, Definition and enumeration of all the Organs and Parts of the Nervous Secondly, The Head, comprising the Cra- 1. Of the Head, Face, and Counte- The Tunica Arachnoidea. The Falx and Tentorium. assist in determining the degree Thirdly, The Organs of the Nervous Sys of Intellect, Character, &c. The Cranium or Skull. lem. 1. Composition. 2. Weight and Size of. 3. Form of. 4. Parts of. 1. Cerebrum. 2. Cerebellum. 3. Falx and Tentorium. 4. Medulla Oblongata. 5. Sensorium, Spinal Cord. The Nerves, Cerebral, Spinal, or The Nerves and their Composi- The Sympathetic Nerve and The Ganglia. Properties and conjoint Actions of The Uses of the Nervous System. and Nervous Systems. The consideration of the Nervous Function is technically termed Neurology (from the Greek vɛupov, a nerve, and λoyos, a discourse, Latin nervus, and French systeme nerveux,) (d) and includes the description of the Brain, Spinal Cord, Nerves, and Organs of Sense, and whenever the the organs and parts of terms "Nervous System," ," "Nervous Matter," or "Nervous Power,” the Ner- are employed without addition or restriction, they are to be understood vous Func- in a general sense, as including or referring to the brain, spinal cord, tion or sys tem. (d) Ante, 52. nerves, plexuses, and ganglia,(e) and, according to some authors, also the CHAP. IX. organs of sense.(f) Nueralgia (from Eupov, a nerve, and axvos, pain,) SECT. II. imports a painful affection of the nerve,(g) whilst under the term Neuro- FUNCTION tica, have been classed all disorders connected with the nervous function.(h) Although Sensation and Motion, (the results of the nervous system,) have been treated as vital, (and certainly life would cease if the nervous functions were either wholly interrupted, or even locally affected in certain parts,) yet, in other parts, although they may be essential to perfection, they are not absolutely indispensable for the continuance of life, and such parts may, in the absence as well of sensation as of motion, maintain a degree of existence; as in the instance of a paralyzed arm or leg, or even an entire side, which, although it will become gradually wasted and reduced in temperature, yet, nevertheless, will not die in the strict sense of that term, and the rest of the frame continue in perfect health and activity.(i) may NERVOUS AND ITS ORGANS. parts. (j) The principal sources of the Nerves are placed within the cranium and First, Enuthe spinal canal. The organs themselves are the Brain and the Spinal meration of Cord, being its continuation. The Brain, again, is composed of or divided organs and into the cerebrum, cerebellum, tuber annulare, and medulla oblongata, parts which differ so much in their structure and organization, as to render it highly probable that they exercise different functions.(k) The Spinal Cord descends from the brain nearly to the sacrum of the pelvis, and through it the body as well as the mind may be stimulated to exertion. Through the Nerves, Plexuses, and Ganglia, the sensations are conveyed from their sentient extremities to the sensorium; and the dictates of the mind are, also, by the former, transmitted to every part of the frame, occasioning muscular motion. The brain is the seat of the Intellectual Faculties, the source of thought. Sensorium is a general term applicable to any source of nervous power; and the whole brain is called the sensorium, though sometimes used as the supposed part where the mental faculties are more particularly seated;() and it is to the defect in or imperfect performance of the nervous function, that most of the corporeal as well as mental diseases and deviations from healthy action, are confessedly attributable.(m) We will examine all these in their natural order, and observe the like arrangement as in treating of the other functions, namely, first considering the several organs and parts, and then the function, or their combined operation. The Head is the cavity containing most of the organs of the Nervous Secondly, System, and of the Senses, and of the Intellectual Faculties. It is com- Of the posed of two principal parts, namely, the Cranium and the Face. The head in geCranium is the upper part above and behind the bony fabric of the face, neral. and protecting the Brain, and is generally of uniform thickness through- The craniout;(n) whilst the bones of the Face are designed to enclose, protect, um and (e) 1 Dungl. Phy. 41; 1 Bost. 175 to Brain, and of the Nerves, arising as well 263. (f) 2 Bell, 365. (g) Coop. Dict. tit. Tic Douloureux; Cyclop. Prac. Med. tit. Neuralgia. (h) Good's Stud. Med. per tot. (i) Soemmering, Corp. Hum. Fab. tom. iv. s. 87; and see 1 Bost, 268, note; id. 192, &c.; 1 Dungl. Phy. 66, 67; ante, 32; Dewees, Prac. Phys. tit. Paralysis. (j) See division, ante, 244; and see the very useful Plates of the Viscera of the Cranium, namely, the Membrane and the from the Brain as from the Spinal Marrow (k) 3 Bost. 293; Jackson, Prin. Med. Prin. Med. 127; Brouss. Phy. 122, &c. &c. (n) As to the Head in general, and In ORGANS. CHAP. IX. and support the muscles and the organs of sense, excepting those of touch SECT. II. and motion, namely, those of sight, hearing, smell, and taste, and parts of NERVOUS the organs of mastication.(o) The natural and proper size of the entire FUNCTION head is, with reference to the rest of the body, one-eighth, (p) whilst the AND ITS cranium, when in due proportion, is almost four times larger than the face, without including the lower jaw (9) Dr. Elliotson observes, that, face in ge- although in the European, the vertical section is almost four times larger neral, their than that of the face, (not including the lower jaw,) yet that the faculties proper dimensions, do not depend upon this proportion, because men of great genius, as Leo, shape, &c. Montaigne, Leibnitz, Haller, and Mirabeau, had very large faces.(r) He further remarks, that the correspondence of Camper's Facial Angle with the above scale in Europeans, is not to be regarded as an exact measure of the understanding, for persons of great intellect may have a prominent mouth; and that it shows merely the projection of the forehead, while the cranium and brain may vary greatly in size in other parts.(s) The head of a European is, in general, extremely symmetrical, although rather globular, the forehead moderately expanded, the cheek-bone narrow, not prominent, directed downwards from the malar process of the superior maxillary bone, the alveolar edge round; the front teeth of each jaw placed perpendicularly; the face oval and nearly straight, its parts moderately distinct, the nose narrow, and slightly aquiline, or at least its dorsum rather prominent: the mouth small, the lips, especially the lower, rather turned out, the chin full and round, and somewhat prominent; in short, the countenance of that style which has been generally considered most beautiful;(t) whilst, in cretinism and idiots, the cranium is obviously imperfectly formed or developed, and mental imbecility is the incident.(u) The Cranium of Europeans, in comparison of the face, is generally very capacious; the area of the face, without including the lower jaw, bearing to that of the cranium, in proportion of only about one to four, and projects but little, if at all, at the lower parts; and hence Dr. Elliotson has observed, that the intellectual faculties of its individuals are susceptible of the highest cultivation, while the senses of smelling, hearing, and seeing, are much less acute than in the dark nations; the circumference, diameter, and vertical arch of whose cranium being smaller than Europeans, and the forehead, particularly, being narrowed, and falling back in a more arched form, consequently, their brain, in general, and particularly those parts which are the organs of intellect, properly so called, must be of inferior size; whereas, on the contrary, the orbits and the olfactory, and gustatory, or rather masticatory organs, being more amply developed, the area of the face bears a greater proportion to the area of the skull as one and one-half to four.(x) It is insisted that in general the more the organ of smell and taste are developed, the greater is the size of the face, and the greater its relative proportion to the cranium; that, on the contrary, the larger the brain, the greater must be the capacity of the skull, and the greater its proportion to the face. On this principle, a large cranium and a small face, it is said, indicate a large brain, with a restricted development of the sense of smell and taste. The character and nature of different animals is determined by the degree of energy with which their different functions are per juries to the same, Coop. Dict. tit. Head; (0) 1 Horn. Anat. 143 to 155; 1 Bell, 36. organs SECT. II. formed. They are guided and impelled by some leading propensity or CHAP. IX. disposition; and that as the cranium and face bear to the brain and of sense the relation of containing and contained parts, the study of their NERVOUS relative proportions is one of the greatest interest to the naturalist, inas- FUNCTION much as they serve as indices of the faculties, instincts, and capabilities ORGANS. of different individuals as well as of classes.(y) Several modes of ascertaining the proportions of the cranium to the face have been suggested; that of Camper and his facial angle has been considered the simplest and best.(z) He drew two straight lines, the one horizontal, passing through the external meatus auditorius, and the bottom of the nostrils; the other running perpendicularly from the convexity of the forehead to the most prominent part of the upper jaw.(b) The angle, which the latter makes with the former, being the proper facial angle, is greatest in the human subject, from the comparative smallness of the brain, and the great development of the mouth and nose, in brutes. In the human adult this angle is about from 65° to 85°; in the ourang outang about from 55° to 65°; in some quadrupeds 20°; and in the lower classes of vertebral animals it entirely disappears.(c) Camper gives the following relative proportions of the facial angle, namely, the European, 80° or 90°; the Chinese, 75°; the Negro, 70°; the ourang outang, 58°; and the monkey, 42°.(d) It has, however, been justly observed, that Camper wrote rather to depict characters of countenances, as belonging to different nations, and even animals, than to connect those characters with any particular comparative mental qualification, though to a certain degree that may be the effect of his system; (e) and in Bell's Essays on the Anatomy and Philosophy of Expression, some defects in Camper's and Blumenbach's systems appear to be established.(f) The following sketches may assist in explanation. A B is the facial line; B C is the horizontal line; and A B C is the angle formed by their intersection, or the facial angle. In this case the perpendicular line D E and the angle DEC being therefore a right angle, or angle of 90°, it is clear that the angle A B C is a little less; it is 80°. :100% No. 1. Ancient Grecian. No. 2. European (Englishman.) DA AND ITS (y) 1 Dungl. Phy. 234. (z) Id. 256; and see the clear explanation in El. Blum. 550; and the scales as in El. Blum. 559. (b) See his interesting work translated by Dr. Cogan, and with explanatory plates published, A. D. 1794. (c) El. Blum. 550. (d) Id. 559, note (h,) where the scale appears rather to differ. (e) 1 Convers. An. Econ. 56, 57; and El. Blum. 550. (f) C. Bell's Essays, &c. 159, 160, 167 to 178, 217, 218, plates. |