The remaining medical works of that famous and renowned physician Dr. Thomas Willis ...: Viz I. Of fermentation, II. Of feavours, III. Of urines, IV. Of the ascension of the bloud, V. Of musculary motion, VI. Of the anatomy of the brain, VII. Of the description and uses of the nerves, VIII. Of convulsive diseases : the first part, though last published, with large alphabetical tables for the whole, and an index ... : with eighteen copper plates / Englished by S.P. esq.

CHAP. XVII. Of the Nerves, which receiving the stores or companies of the Spirits from the Cerebel, bestow them on the Acts of the involuntary Function.

WE have already shewed, that out of the annular Protuberance (which is a certain Process of the Cerebel) three pairs of Nerves, to wit, the fifth, sixth, and seventh immediately arise. We have said that Protuberance to be as it were a Repository or Store-house, wherein the Spirits flowing out of the Cerebel, and to be derived into the depending Nerves, as occasion serves, are kept: and in the mean time, whilst they remain there, they who stream out from either middle Marrow of the Cerebel divisively, meeting mutually in this Cirque, are united together. But as the aforesaid three pairs of Nerves receive the forces of the Spirits from the Cerebel by the mediation of that Protuberance; so also the eighth pair ha∣ving its rise near the insertion of the other (viz. the lowest) medullar Process sent down from the Brain, seems to derive by its passage the influence of the Spirits no less from the Cerebel: wherefore when these four conjugations of Nerves owe the Tribute of their Spirits wholly to the Cerebel, if I shall shew that all these Nerves serve chiefly and almost only to the involuntary acts of the Senses and Motions, surely this will be a signal Argument, that according to our Hypothesis, the office of the Cerebel is to beget and to dispense the animal Spirits requisite for the involuntary Functions.

Therefore in the first place we observe of the fifth and sixth conjugation of Nerves, that as this arises out of the Basis of the greater Ring, and that from its sides both in man and in four-footed beasts; the fifth pair being carried more forward, distri∣butes its branches into the Glandula's of the Eyes, into the Nostrils, into the Palate, Teeth, yea and into most parts of the Face and Mouth; but the sixth pair is wholly bestowed on some Muscles of the Eyes. Further, out of the trunk of the fifth pair two shoots, and another out of the Nerve of the sixth pair bending back behind, meet together; and what is wonderful, and not before taken notice of by Anatomists, the intercostal Nerves, destinated to the Praecordia and Viscera, do make a Trunk; so that the Nerves of the fifth and sixth pair stretch out a double Ramification, to wit, one more above about the parts of the Mouth and Face, and the other lower through the Viscera of the middle and lowest Belly. But it will appear clearly to any one considering this thing more carefully, that the chief branches of either partition are imployed about the involuntary offices of Motion and Sense, of which sort those are chiefly, that either cause the passions, or perform the natural Instincts.

1. Concerning the intercostal Nerve, which (as was said) being radicated in the

Nerves of the fifth and sixth pair, depends as to its origine wholly on the Cerebel, it is not here to be doubted but that it looking towards the Praecordia and Viscera in a man, and towards these latter only in most four-footed beasts, is bestowed on the Functions only vital and merely natural, and so confers little or nothing to sponta∣neous actions. Further, forasmuch as this Nerve reaching forth into the Praecordia and Viscera of the whole Abdomen, is continued by its superior ramification also into the Eyes, as also into the parts of the Mouth and Face; certainly from hence a true and genuine reason may be given wherefore in every passion the Eyes, Face, and Mouth do so correspond with the affections of the Praecordia, often unknown to us or against our minds, that oftentimes we are compelled to betray the most intimate sense of the Heart by the countenance and aspect. Yea, hence a reason may be brought, why in sneesing, yawning, laughing, and crying the Muscles of the Face conspire so in motion with the Praecordia. Besides, when in man different from any other living Creatures besides, as we shall shew afterwards, many shoots are sent from the intercostal Nerve to the Nerve of the Diaphragma; this certainly is the cause why risibility is the proper affection of man.

But the Trunk of the fifth pair being carried more forward, and distributing its branchings through the parts of the whole Face, causes the same not only to be pathetically moved, and figured according to the affections of the Praecordia; but also produces some acts, both of motion and sensation, of another kind, which for the most part are involuntary, and so seem to depend wholly upon the Cerebel im∣mediately. For example, this Nerve imparts shoots to either mandible requisite for the business of chewing: but it is very well known, that the taking in of the food at the mouth is the first and oldest business of every Animal, which indeed is taught by natural Instinct before any knowledge of the Brain. But as to the Senses, the bran∣ches of this pair conduce something to the smelling, but for the most part for the knowing and chusing of savors. Hence it comes to pass, that as odors refresh the Brain by the smelling Nerves, so also they affect the Cerebel by the branch of this pair, and are wont by that means to recreate the Viscera and Praecordia. But sapors or tastes (for that they are almost the peculiar Province of this) carry whatsoever they have of pleasantness or trouble, first to the Spirits inhabiting the Cerebel, and then by their consent to the Praecordia and Viscera. Hence it is, that a Pectoral not only allays hunger, but the very first tasting of Wine raises up those that are fainting or swooning away. Moreover, forasmuch as from this Nerve certain branches serve for the taste, and others for the smell, there is contracted so strict an affinity between either of these Sensories, that nothing pleases the taste unless it be approved of by the smell: and the loss of one of these senses oftentimes causes the privation or the dimi∣nution of the other.

2. Concerning the Nerve of the sixth conjugation we observe, that as one shoot is bent back for a root of the intercostal Nerve, the remaining Trunk of it being car∣ried forward towards the ball of the Eye, is distributed to two of its Muscles, viz. to the seventh, proper to beasts, and to the drawing Muscle. Hence may be infer∣red, that this Nerve, besides the influence of it bestowed on the vital and natural Function, serves also for the producing some pathetick motions of the Eye, to wit, such as are wont to obey the affections of the Praecordia and Viscera; so that the whole provision of the animal Spirit, which it receives from the Cerebel, it bestows only on involuntary acts.

3. The seventh pair, or the hearing Nerves, seem also to depend upon the Cere∣bel, forasmuch as they take their originals out of the annular Protuberance: but the use of them is a little otherwise in man than in four-footed beasts. For in him the annular Protuberance is one, and that very big, from whose lower margin the audi∣tory Nerves proceed: but in Brutes the Protuberance is twofold, viz. one greater, sent down from the Cerebel, in which the beginnings of the fifth and sixth pair of Nerves consist; then near this there is another lesser, and as it were secondary, from which the auditory Nerves proceed. This lesser and lower Ring doth not so mani∣festly depend on the Cerebel, as the former; but there is stretched out from either height of it a white medullar line upon the oblong Marrow in the bottom of the fourth Ventricle: so as this seems to receive either the Spirits from the oblong Mar∣row, or at least to carry into the same the sensible Species: for what use it is so con∣stituted shall be inquired into afterwards; for concerning these Nerves of the seventh pair, forasmuch as some offices of them very much illustrate the government or oeco∣nomy

of the Cerebel, we shall discourse here a little more largely.

Therefore in man, who hath got a great and undivided annular Protuberance, the auditory Nerves coming out of its margin or brim, shew its stock received of the Cerebel: by which means we may see the tasks of those Nerves quadrate with the assigned government of this. We have shewn before the Processes (which in a manner may be called distinct Nerves) of the seventh pair to be twofold on either side: one, the softer of these, serves only for the sense, but the other harder seems to perform some motions. This latter Nerve, being carried without the Skull, is divided into three branches, all which serve to pathetick motions, or at least to such as are performed without consulting the Brain.

1. The first of them being bent back towards the auditory passage, is bestowed on the Muscles of the Ear. Without doubt, by the action of this, it is effected, that all Animals at the sudden impulse of a sound or noise, erect their Ears at it were to catch the sound too soon passing by. 2. The other branch of this same Nerve climb∣ing over the Muscles of the Jaw, sends forth shoots towards either corner of the Eye: which are inserted into the Muscles lifting up the Eye-lids; the office of which is cer∣tainly to open suddenly the Eyes at the sudden approach of any sound, and as it were to call them forth to watch, that by the stroke of the Air being brought to the Ear, the Eye might presently look about to see what is the matter, and whether there might be any danger near or not: which also all Creatures do unthought of. 3. The third branch of the same auditory Nerve descending towards the root of the Tongue, is distributed to its Muscles, and to those of the Bone Hyoides, and so actuates some of the Organs for the framing the Voice. For this reason in some measure it comes to pass, that living Creatures being astonished at an unaccustomed or horrid sound, presently putting forth an uncertain voice, cry out and make a noise. But the con∣formation of these kind of Nerves in man serves for another more noted use, to wit, that the voice might fitly answer to the hearing, and that this might be set as the Echo of the sound admitted by this: so indeed, as on the other side, there be two Nerves of the same pair, the sound is received by the hearing through one, which is rendred again by the voice through the other. The common and extrinsick Echo consists in this, that a certain undulation or waving of the Air shaken or moved, be∣ing stirred up, and tending towards or about, when by reason of some stop or hin∣derance, it cannot go any further directly, being presently repercussed or struck back or reflected at certain angles, it is terminated contrary to the former bound. In like manner, in the hearing, the impression of the sound, or the Species admitted to the Ears by the hearing faculty of the Processes of the same or neighbouring Nerve, and being carried inwardly towards the Cerebel and common Sensory; and from thence again reflected on the vocal process, it is carried out by the Mouth. But be∣tween these there is some difference, to wit, forasmuch as the outward Echo renders back the sound immediately; but the sound of the Hearing is not necessarily carried forth at the mouth presently, but that this leaves an Idea in the Head, according to which afterwards, as occasion serves, the voice is formed, which bears the type and image of that, though some time before admitted.

But here (if I may digress a little) we should inquire in what part of the Head the Ideas of sounds are left: whether only in the Brain, which is the Chest of Memory acquired as it were artificial; or whether not also in the Cerebel, which is the place of natural memory? Truly we suppose, that sounds belong to both these, as it were to distinct Store-houses. Every audible impulse being struck against the Ear, it is pre∣sently carried by the passage of the auditory Process to the annulary Protuberance; but from thence it is carried, as other sensible Species, to the chamfered bodies or the com∣mon Sensory; (which way it passes thither, shall be shewed afterwards) this impres∣sion tending from thence farther, and being also delivered to the Brain, stirs up the Imagination, and so leaves in its Cortex an image or private mark of it self for the Memory. Further also, as the auditory Process depends on the Cerebel, and receives from it the provision of the animal Spirits: so it is most likely, that by the recess of the same Spirits the Ideas of the Sounds are conveyed also to the Cerebel; which forming there footsteps or tracts, impress a remembrance of themselves, from whence when afterwards the Species there laid up are drawn forth by the help of the vocal process, voices, like the sounds before admitted, and breaking forth in a certain ordained series, come to be made.

Hence it is usual, that musick or melody is soon learnt by some men, which after∣wards

they bring forth with exact Symphony, without any meditation or labour of the Brain; to wit, from the distinct accents of the heard harmony, the Spirits moving within the Cerebel are disposed into peculiar Schemes; according to which, when they flow on both sides into the vocal process of the auditory Nerve, they render as it were with a certain spontaneous voice, and like a Machine or Clock with the succession of Species, the measures or Tunes of the Instrument which they had drunk in at the ears. Without doubt hence the reason may be sought, why some men learn Musick without any trouble, and others hardly or not at all. For it is observed, that some Children, before they can speak distinctly, quickly sing, and remember certain Tunes; whilst others, though very ingenious men and of excellent memory, are very Fools at Musick, and become uncapable, as an Ass for the Harp; wherefore 'tis commonly said, that some have musical ears, and others are wholly destitute of that faculty. In the mean time, 'tis to be confessed, that in these the Organs of the Voice are not defective; but all the fault, though wrongfully, is cast on the hearing.

But in truth the genuine cause of this defect seems to consist in this, that when in all, the audible Species go to the Cerebel sooner and more immediately than the Brain; yet in some the Cerebel being harder, and not easily yielding to the received impressions, those Species, because they could impress nothing of themselves in their passing to the Cerebel, being carried towards the common Sensory, leave their Types or Ideas chiefly and almost wholly in the Brain: which part being still busied with disturbed motions, is less apt to keep distinctly the composures of Harmony. But in the mean time, in others the Species of audible things, besides that they are carried to the common Sensory and to the Brain, do also affect the Cerebel, especially if they are harmonically figured (forasmuch as in them there is a softer capacity of the im∣pressions) with a peculiar order and Scheme of the animal Spirits: where, as the Species of the Harmony being disposed in convenient little places and cells are kept, afterwards they flow out from thence, almost unthought of, without any endeavour or labour of remembrance, but in a distinct series, and as it were in composed modes and figures, and so by blowing up the vocal processes, they constitute sweet Tunes and vocal Musick.

If that the divers ways of passage are inquired into, to wit, whereby the audible Species, being carried into the annular Protuberance, do get both to the Brain and Cerebel; I say it is not improbable, but out of that Protuberance both a passage lyes open into the underlying tract of the oblong Marrow, and as it were the high road; as also another passage is opened into the Cerebel through the medullar processes of the same Ring. But lest there should perchance be a confusion of the animal Spirits and the sensible Species, (which indeed can hardly be avoided) if the way made for their passage should lye open into various passages and manifold apertures; therefore concerning this it may well be supposed, that the Ideas of the Sounds pass through the Cerebel, when they are carried to the common Sensory; which region being first past, they are at length brought by a by-path, viz. through the orbicular Prominences to the chamfered Bodies: which perhaps is partly the reason, that in the Hearing the perception of the sense succeeds so late, and the impulse of the object, in respect of sight, follows so slowly.

Whilst therefore the audible Species passes through the Cerebel, in some men, it leaves in this region (for that it is of a soft temper, and fit for the receiving im∣pressions) tracts and marks of it self, and so they obtain musical ears. But in others who have a harder frame of the Cerebel, they produce no tracts of the same Sounds, and therefore such are wholly destitute of the faculty of Musick.

As therefore we suppose the audible Species to pass through the Cerebel after this manner, a reason may be given from hence, wherefore Musick does not only affect the Phantasie with a certain delight, but besides chears a sad and sorrowful Heart; yea, allays all turbulent Passions excited in the Breast from an immoderate heat and fluctuation of the blood. For since the animal Spirits, serving for the motion of the Praecordia, are derived from the Cerebel; as the perturbations conceived in the Brain, the influence being transmitted hither by moving these Spirits in the Fountain it self, transfer the force of their Affections on the Breast; so the Melody introduced to the Ears, and diffused through this Province, does as it were inchant with a gen∣tle breath the Spirits there inhabiting, and composes them, called off from their fury, to numbers and measures of dancing, and so appeases all tumults and inordina∣tions therein excited.

From these may in some measure be known the reason of the difference, why the hearing Nerves are after a different manner in man and in four-footed beasts: for, be∣cause in these there is little need that the audible Species should pass through the Cerebel, either for the reciprocations of the sound heard, by the voice, or for the impressing there the Tunes of the Harmony (for neither is Musick required, what∣ever Poets feign, to the taming the Affections which move the breasts of beasts) therefore in these (I mean in four-footed beasts) the annular Protuberance dispensing the animal Spirits to the auditory Nerves, and receiving from them the sensible Spe∣cies, requires not so strict an affinity with the Cerebel: yea, whenas it may suffice, that those Nerves arise from the oblong Marrow, yet the annular Protuberance, as it were a common Porch, ought to be prefixed to them; to wit, in which both the Spirits going out from either side, and the sensible Species to be carried to either, ought first to be mixed and united together, lest otherwise every sound should become double.

Among the Nerves which are seen to belong to the Cerebel, and to perform its offi∣ces, lastly follow the eighth or wandring pair, which indeed hath its rise out of the com∣mon Trunk of the oblong Marrow, near the place where the last process of the Ce∣rebel is terminated, and over against where the pyramidal bodies, being produced from the annular Protuberance, end: so that we think these Nerves also, by that process coming between on either side, and also perhaps in some measure through the passage of the pyramidal bodies, do derive all manner of influence of the animal Spirit from the Cerebel.

The beginning of these consists of very many fibres and filaments or little threads presently distinct one from another; to which belongs, from the very beginning of every Nerve, a noted Trunk arising out of the spinal Marrow. The description of the wandring pair of Nerves, and its protension into the Praecordia and some Viscera, are added hereafter. For the present it shall suffice, that we take notice, that for as much as this Nerve is bestowed chiefly on the Praecordia, the acts whereof are in∣voluntary, and are performed without our care or knowledge in sleep as well as wa∣king; and for that the same Nerve seems to receive the forces of the Spirits wholly from the nearer fountain of the Cerebel; from hence it may certainly be well con∣cluded, that the government or oeconomy of the Cerebel regards only the involun∣tary Function.

So much for the Nerves, which being subjected to the Government and Laws of the Cerebel, seem to obey and serve under it: among which moreover ought to be placed the fourth pair, or the pathetick Nerves of the Eyes, to wit, which arising out of the first processes of the Cerebel, come between that and the orbicular Pro∣cesses; of the use of which we have spoken already. Further, we shall here take notice, that some other Nerves to be described below, for that they communicate with the aforesaid Nerves near their originals, cause also some involuntary acts to be performed; of which sort are first the ninth pair, the spinal Nerve accessory to the wandring pair, also the Nerve of the Diaphragma, and some others, as we shall shew more at large in the particular History of the Nerves.

We may also observe, concerning the Nerves but now described, which owe their stock to the Cerebel, and seem to be designed for the offices of the involuntary Function, that sometimes some of them, though of another Dominion, are compelled to obey the beck and government of the Brain: for we are wont to draw the parts of the Face, usually moved pathetically and unthought of, and also at our pleasure, into these or those Configurations or postures: we are able also in a measure to alter the motions and actions of the Praecordia and Viscera at the will or command of the Appetite. The reason of these is, partly because the Nerves of either Government communicate variously among themselves with shoots sent forth one to another, so that oftentimes the offices of the one are drawn into the parts of the other. But be∣sides, we have mentioned before, that the sensible impression being inflicted on the parts of the involuntary Function, forasmuch as it is vehement, like a strong waving of water, passing through the Cerebel, affects the Brain it self. In like manner it may be thought concerning the motion which belongs to those parts, viz. that made after the ordinary manner, that it is performed by the command of the Cerebel. Not∣withstanding some more severe Edicts of the Brain, by the by-passage of the Prominen∣ces, belong also to the Cerebel, and determine the Offices of the Inhabitants of it to be performed at the beck of the Appetite. As every one sees that violent Passions

(whether the will be privy or not) easily do this; why therefore may not the will it self also, as occasion requires, exercise the same dominion? But in the mean time, this derogates nothing from the priviledges of the Cerebel, that it may not be called a free and municipal City, and so Mistress of the involuntary Function; for that in some few it is after the manner of the Brain: because the Brain it self in many things is compelled to serve the Cerebel and its Government, as we have already shewn, and is necessarily bound to it. For the Brain owes much to the Cerebel, forasmuch as it receives from the vital Function (which is of its Province) the provision of the blood, and by consequence the Tribute of the Spirits produced of it: so indeed that both these parts, though Principals, perform mutual offices, and as it were in a circle, require and accomplish services one for another.