of filaments destined for both motion and sensibility; that the encephalic nerves, which have but one root, are destined for one of these exclusively, and that they are either nerves of motion, or of sensation, according as their roots arise from the anterior or the posterior tract of the medulla. It has already been remarked, that the medulla oblongata, according to some anatomists, is composed of three fasciculi or columns on each side;-an anterior, a middle, and a posterior; and it has been affirmed by Sir Charles Bell, that whilst the anterior column gives origin to nerves of motion; and the posterior to nerves of sensibility; the middle gives rise to a third-order, having the function of presiding over the respiratory movements; and which Sir Charles, accordingly, calls respiratory nerves. To this third order belong, the accessory nerve of Willis or superior respiratory; the vagus; the glosso-pharyngeal; the facial, called by him the respiratory nerve of the face; the phrenic; and another having the same origin-the external respiratory. Sir Charles's views, if admitted, lead, consequently, to the belief, that there are at least three sets of nerves,-one destined for sensation; another for motion; and a third for a particular kind of motion-the respiratory; and that every nerve of motion communicates to the muscles, to which it is distributed, the power of aiding, or taking part in, motions of one kind or another; so that a muscle may be paralyzed, as regards certain movements, by the section of one nerve, and yet be capable of others of a different kind, by means of the nerves that are uninjured. The accompanying plate exhibits the system of respiratory nerves, as given by Mr. Shaw, son-in-law of Sir Charles Bell, who was prematurely snatched from existence, after having made numerous useful contributions to medical and surgical science. 8. Branches of the glosso-pharyngeal. 9. Lingualis, sending branches to the tongue, and to the muscles on the fore part of the larynx. 10. Origins of the superior external respiratory or spinal accessory. 11. Branches of the last nerve proceeding to the muscles of the shoulder. 12 12 12. Internal respiratory or phrenic passing to the diaphragm. The origins of this nerve are seen to be much higher than they are generally described. 13. Inferior external respiratory, to the mus cles on the side of the chest. Yet this division is by no means universally admitted; and even by some who are of opinion, that the sensitive and motor filaments arise from distinct tracts of the spinal cord, it is denied that this is the case with those that originate from the upper part of the cord; there being in the medulla oblongata a blending of the sensitive and motor tracts which cannot easily be explained. Pathological cases, too, occasionally 1 Manual of Anatomy, &c., 3d edit., Lond., 1822. Reprinted in this country. occur, which throw great difficulty on this matter. Two of the kind have been related by Mr. Stanley and Dr. Budd,' in which there was disease confined to the posterior column; yet sensation remained unimpaired, whilst the power of motion in the lower extremities was lost. 2 Much evidently remains to be accomplished, before the precise arrangement of the columns of the spinal cord, and of the relations of the nerves connected with them, can be esteemed established. Sir Charles Bell, indeed, subsequently renounced his first opinion, that the posterior roots of the spinal nerves proceed from the posterior column, and described them as arising from the middle or lateral column; affirming, at the same time, that it is not impossible that the posterior column may be connected with the sensitive roots of the spinal nerves, although he has not hitherto succeeded in tracing it. Messrs. Grainger and Swan maintain, that both sets are connected with the lateral columns only; the anterior and posterior lateral fissures definitely limiting the two roots. Perhaps, as suggested by Dr. Carpenter,3 both these statements may be too exclusive. The anterior roots would seem to have a connexion with both the anterior and lateral columns; and the posterior cannot be said to be restricted to the lateral column, some of their fibres entering the posterior division of the cord. Most physiologists are now of opinion, both from experiment and reflection, that there is no special column destined for respiration, and that there appears to be nothing so peculiar in the action of the respiratory muscles, that they should require a distinct set of nerves." Sir C. Bell proposed a further arrangement of the nerves, more natural and philosophical than the unmeaning numeration according to the system of Willis, and better adapted to facilitate the comprehension of this intricate portion of anatomy. According to this, all the nerves of the body may be referred to two great classes-the original, primitive or symmetrical, and the irregular or superadded. It has been already remarked, that a division of the spinal cord has been presumed to correspond to the cerebrum; and another to the cerebellum. Now, every regular nerve has two roots, one from the anterior of these columns, and another from the posterior. Such are the fifth pair; the sub-occipital; the seven cervical; the twelve dorsal; the five lumbar; and the six sacral,-that is, thirty-two perfect, regular, or double nerves, including, to state more briefly, all the spinal nerves, and one encephalic-the fifth pair. The fifth pair is found to arise from the encephalon by two roots, and to have a ganglion upon the posterior root. It is, accordingly, classed with the spinal nerves; and, like them, according to Sir Charles Bell, conveys both motion and sensibility to the parts to which it is distributed. These regular nerves are common to all animals, from the zoophyte to man. They run out laterally; or in a direction perpendicular to the longitudinal division of the body; and never take a course parallel to it. The other class is called irregular or superadded. The different 'Medico-Chirurgical Transactions, vol. xxiii., Lond., 1840. Nervous System, &c., 3d edit., p. 234. London, 1836. 3 Principles of Human Physiology, 2d Amer. edit., p. 125. Philad., 1845. nervous cords, proceeding from it, are distinguished by a simple fasciculus or single root. All these are simple in their origins; irregular in their distribution; and deficient in that symmetry which characterizes those of the first class. They are superadded to the original class; and correspond to the number and complication of the superadded organs. Of these, there are the third, fourth, and sixth, distributed to the eye; the seventh, to the face; the ninth, to the tongue; the glossopharyngeal, to the pharynx; the vagus, to the larynx, heart, lungs, and stomach; the phrenic, to the diaphragm; the spinal accessory, to the muscles of the shoulders; and the external respiratory, to the outside of the chest. The reason of the seeming confusion in this latter class is to be looked for in the complication of the superadded apparatus of respiration, and in the variety of offices it has to perform in the higher classes of animals. The accompanying plate exhibits, in one view, the nerves destined to move the muscles in all the varieties of respiration, speech, and facial expression. In the plate of regular or symmetrical nerves, A is the cerebrum, B, the cerebellum, C C, the crura cerebri, D D, the crura cere. belli, E E E, the spinal marrow. 11. Branches of the fifth pair, arising from the union of the crura cerebri and crura cerebelli, and having a ganglion at the root. 2 2. Branches of the sub-occipital nerves, which have double origins and a ganglion, 3 3. Branches of the four inferior cervical nerves, and of the first dorsal, forming the axillary plexus. The origins of these nerves are similar to those of the fifth and of the sub-occipital. 4 4 4 4. Branches of the dorsal nerves, which also arise in the same manner. 5 5. The lumbar nerves. 6 6. The sacral nerves. So much for the anatomy of two great portions of the nervous system. There remains to be considered a third, and by no means the least interesting or important. 4. Great Sympathetic.-This nerve, called also trisplanchnic, splanchnic, ganglionic, great intercostal, vegetative, and organic, is constituted of a series of ganglions, joined to each other Fig. 22. P Sympathetic. a by a nervous trunk, and extending Roots of a Dorsal Spinal Nerve, and its union with down the side of the spine, from the base of the cranium to the os coccygis or lowest bone. It communicates with each of the spinal nerves, and with several e, c. Anterior fissure of the spinal cord. a. Anterior root. p. Posterior root, with its ganglion. a'. Anterior branch. p'. Posterior branch. s. Sympathetic. spinal nerve by a white and a gray filament. e. Its double junction with the anterior branch of the of the encephalic; and from the ganglions, formed by such communication, sends off nerves, which accompany the arteries, and are distributed particularly to the organs of involuntary functions. At its upper part, it is situate in the carotid canal, where it appears under the form of a ganglionic plexus; two filaments of which proceed to join the sixth pair of encephalic nerves, and another to meet the Vidian twig of the fifth pair. By means of the fifth pair, it communicates also with the ophthalmic ganglion, which Bichat considered to belong to it. On issuing from the carotid canal, the nerve passes downwards, along the side of the spine, to the sacrum; presenting a series of ganglions;-three in the neck, -the superior, middle, and inferior cervical; twelve in the back, the thoracic; five in the loins, the lumbar; and three or four in the sacrum,-the sacral. When it reaches the coccyx, it terminates by a small ganglion, called coccygeal; or by uniting with the great sympathetic of the opposite side. The ganglions are of an irregular, but generally roundish, shape. They consist of nervous filaments, surrounded by a reddish-gray, pulpy, albuminous, or Great Sympathetic Nerve. 1. Plexus on the carotid artery in the carotid foramen. 2. Sixth nerve (motor externus). 3. First branch of the fifth, or ophthalmic nerve. 4. A branch on the septum narium going to the incisive foramen. 5. Recurrent branch or Vidian nerve dividing into the carotid and petrosal branches. 6. Posterior palatine branches. 7. Lingual nerve joined by the chorda tympani. 8. Portio dura of the seventh pair. 9. Superior cervical ganglion. 10. Middle cervical ganglion. 11. Inferior cervical ganglion. 12. Roots of the great splanchnic nerve arising from the dorsal ganglia. 13. Lesser splanchnic nerve. 14. Renal plexus. 15. Solar plexus. 16. Mesenteric plexus. 17. Lumbar ganglia. 18. Sacral ganglia. 19. Vesical plexus. 20. Rectal plexus. 21. Lumbar plexus (cerebro-spinal). 22. Rectum. 23. Bladder. 24. Pubis. 25. Crest of the ilium. 26. Kidney. 27. Aorta. 28. Diaphragm. 29. Heart. 30. Larynx. 31. Submaxillary gland. 32. Incisor teeth. 33. Nasal septum. 34. Globe of the eye. 35, 36. Cavity of the cranium. gelatinous substance, which differs from the gray matter of the brain. Sir E. Home1 considers their structure to be intermediate between that 'Lect. on Comp. Anat., v. 194, Lond., 1828. 3 of brain and nerves; the brain being composed of small globules suspended in a transparent elastic jelly; the nerves made up of single rows of globules, and the ganglions, consisting of a congeries of nervous fibres compacted together. Volkmann and Bidder, and Reichert,2 consider the sympathetic nerve-fibres to be distinct in size and structure from the cerebro-spinal; but Valentin maintains there is no difference. Authors are by no means agreed with regard to the uses of these ganglions. Willis, Haller, and others, considered them to be small brains for the secretion of the nervous fluid or animal spirits; an opinion, which has been embraced by Richerand,' and Cuvier; the latter of whom remarks, that the ganglia are larger and more numerous when the brain is deficient in size. Lancisi, and Vicq d'Azyr, regarded them as a kind of heart for the propulsion of these spirits, or as reservoirs for keeping them in deposit. Scarpa treats them as synonymous with plexuses; but plexuses with the filaments in close approximation; and plexuses he regards as ganglions, the filaments of which are more separated. He consequently believes, with many physiologists, that their office is to commingle and unite various nervous filaments with each other. Dr. Wilson Philip' thinks, that they are secondary sources of nervous influence; that they receive supplies of it from all parts of the brain and spinal marrow, and transmit the united influence to the organs to which the nerves are distributed; whilst some conceive, that at least one office is to communicate irritability to the tissues. 10 Johnstone," Reil," Bichat, and others, are of opinion that their use is to render the organs, which derive their nerves from them, independent of the will. 13 These views are sufficiently discordant; and well indicate the intrinsic obscurity of the subject. That of Dr. Philip is the most probable. Containing the vesicular or gray matter, which seems to be everywhere concerned in the production of nerve-power, the ganglia may be regarded as agents of nervous reinforcement; although we may remain uncertain as to the mode in which their office is executed.14 It is affirmed 1 See, on the Histology of the Organic or Sympathetic Nervous Fibres, Mr. Paget, Brit. and For. Med. Rev., July, 1842, p. 279. * Müller's Archiv., 1844, cited by Mr. Paget, in Brit, and For. Med. Rev., April, 1845, p. 572. 3 Cerebri Anatome, cui accessit Nervorum Descriptio, &c., Lond., 1664, cap. xxvi. • De Verâ Nervi Intercostalis Origine, Gotting., 1793; Collect. Dissert. Anat., ii. 939; and Oper. Minor, i. 503. 5 See Appendix to Eng. edit., by Dr. Copland. • Leçons d'Anatomie Compar. Introd., p. 26. 7 Dissert. de Structurâ Usuque Gangliorum, ad J. B. Morgagnium, in Morgagni Adver. Anat., v. 101, Lugd. Bat., 1741. De Nervis Comment., cap. ii. 320. 9 Philosoph. Transact. for 1829; and Inquiry into the Nature of Sleep and Death, Lond., 1834, p. 14. 10 Fletcher, Rudiments of Physiology, P. ii. a. p. 68, Edinb., 1836. "Philosophical Transactions, vols. 54, 57, and 60; Essays on the Use of the Ganglions of the Nerves, Shrewsbury, 1771; and Medical Essays and Observations relating to the Nervous System, Evesham, 1795. "Archiv. für die Physiol., s. 226, vii., Halle, 1807. 13 Anatomie Générale, tom. i. 200, and ii. 405. 14 See the excellent article by Wagner, entitled Sympathischer Nerv, Ganglienstructur und Nervenendigungen, in his Handwörterbuch der Physiologie, 17te Lieferung, s. 360, Braunschweig, 1847; another by Budge on the Sympathetic, with special relation to the Heart's action, Ibid., s. 406; and on the Sympathetic Ganglia of the Heart by Wagner, Ibid, s. 450. |