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. II. The Parts of the oblong Marrow, and the rest of the hinder Parts of the Head are recounted, and their Dissection shewn.

HAving described both the Meninges, and the ramifications of the Vessels in them, also the fabrick of the Brain, properly so called; and next shewed its outward partition gathered together into folds about the shanks of the ob∣long Marrow, and either middle or marrowy part of it hung to the chamfered bodies; we will now follow the remaining parts of the Head in order.

The chamfered or streaked bodies, or the tops of the oblong Marrow, are two lentiform Prominences, which are beheld within the former Ventricles of the Brain, as they are commonly termed; the heads of these, which are more large and blunt, incline mutually one to another, and are almost contiguous. Out of the angle of this inclination the Fornix arises with a double root; to which is subjected or underlaid a certain transverse medullary process, and seems to knit together these streaked bo∣dies, as may be seen in the seventh Table GG: but the ends of those bodies, being made sharper, are reflected outward, and make as it were two sides, with a sharp triangle, to whose anterior superficies the marrow of the callous body sticks for a long tract; where, if these bodies be cut long-ways through the midst, the medullary streaks (as was already said) will presently appear. The figure and place of these, as also the medullary chamferings, are truly represented in the eighth Table.

Where the streaked bodies end, the chambers or Thalami, as they are termed, of the optick Nerves, possess the next part to the oblong marrow; to wit, in this place,

its shanks rise into unequal protuberances, out of the ridges of which the Optick Nerves arise, and from thence, being bent down in the fore-part with a certain com∣pass, they joyn together about the base of the same marrow, and seem to be united; by and by being again parted, and going forward towards the ball of the Eye, they go out of the Skull. In this place the shanks of the oblong marrow in a Man are for the most part distinct, and gaping one from another, leave a descending opening, which is the passage to the Tunnel; but in most four-footed Beasts the shanks of the same medullary stocks are there distinct, only a little lower, and have a chink cut for the Tunnel: but the ridges of them, in which the beginnings of the Optick Nerves lye hid, are somewhat conjoyned, and for the space of half an inch do grow together. Wherefore in Brutes there is one hole before this growing together, and another be∣hind it, both which lead towards the Tunnel. The reason of this difference is, be∣cause in a Man, for that the frame or substance of the brain it self is very large, and that its marrowy parts are remote one from another, it is behoveful for its shanks, whereby the tops of the oblong marrow may be the better fitted to the same, to be separated, and from their mutual touching to be bent into a greater aperture. Hence it is observed, that in a Man the shanks of the oblong marrow, from the hanging on of the brain, go forward with a greater angle of inclination, and with a certain bend∣ing compass; but in Brutes the same lye almost parallel. After what manner these parts are formed in an humane brain the third and fourth Figure shews; after what manner they are in four footed Beasts is shewn in the seventh Figure.

From the same ridges of the medullary shanks, from whence the Optick Nerves take their origines, certain medullary processes arising, and being dilated on either side above the brim of the second hole, grow together about the root of the pineal Glandula. These processes (as it seems) are those parts, which the Famous Cartes supposes to be Nerves belonging to the pineal Glandula: but I rather suspect them to be productions only, by which the Optick Nerves may also communicate near their origines. Their figure is very well described in the seventh Table.

After the Thalami or Chambers of the Optick Nerves, other notable protuberances, commonly called Nates and Testes, the Buttocks and Testicles (of the brain) grow to the superior part of the medullary Trunk or stem, and cover its superficies about the space of an inch; and for that they are not contiguous in the midst, there is under them a certain hollowness in their whole tract. These protuberances are lesser in a Man, also in a Dog and Cat; lastly, if we observed rightly, in other living Crea∣tures, which are newly brought forth, that are impotent, and not instructed for the finding out of food. In a Calf, Sheep, Hog, and the like, they appear far greater: in Fishes and Fowls they are wholly wanting.

In number they are four, viz. two grow to either side of the oblong marrow. The former called Nates or the Buttocks, seem the greater and principal; to which the other latter called Testes or the Testicles, hang as if growing out of them. As to their figure, they are round, and are commonly taken for two shanks on either side of the brain and Cerebel planted near, which being bent inwardly, and turned back one towards the other, are said to grow together, and so to constitute the oblong marrow. But this opinion, as we shall shew more largely hereafter, by the dissection ordered according to our Method, is clearly false. For it plainly appears, that the brain is fixed, long before these bodies, to the oblong marrow; nor is there any commerce between these and that, unless very remote.

But if the site of these parts, and their respects and habitudes to the neighbouring bodies, be well noted, it will appear plainly, that they make as it were a certain peculiar Region wholly distinct from the Brain and Cerebel, also from the oblong marrow it self. Their situation is remote enough from the fore-parts, and sufficient∣ly separated by the Cavity or Ventricle under-lying from the medullary stock or stem: yea a proper way, or one process, seems to lead from the long marrow into these prominences, and another to go from them, and thence to be carried into the Cerebel. From hence we may suspect, that these prominences (especially the Nati∣form, or of the shape of a Buttock, which are the chief) are certain places of diver∣sion, in which the animal Spirits go apart in their passage from the oblong marrow into the Cerebel, and from this to that on the other side, and there stay for some animal uses, of which we shall speak hereafter. As to the way, which leads from the oblong marrow into these prominences; it is manifest, that beneath the origines of the Optick Nerves on either side a medullary Process descends, with little Villages

proper for it self, which terminates in the aforesaid prominencies. Then, if from these, you look for a passage out, it is equally clear, that from the hindermost pro∣minences, which are called Testes, on either side, a medullary process doth obliquely ascend, which being dilated into the Cerebel, is divaricated through its whole frame. But that the Natiform or Buttock-formed Prominences are Principals, and the Testes their dependences, or the heads of medullary Processes, which are carried from thence into the Cerebel, manifestly appears in a Sheep, Calf, or Horse, and in some others, where the Nates are of a noted magnitude, the Testes of a very small bulk grow to them, and in the middle between these the medullary Processes, the Appendices of the former Prominences, exist. The aforesaid Prominences, as also the medullary Processes, which lead forward and backward, to and from them, are aptly repre∣sented in the fourth Table, but yet more clearly in the eighth Table TT. PP.

Further, because the animal Spirits residing in either Promptuary and Appendix, be∣fore they are carried to the Brain, ought to be confounded and mingled together, there∣fore the two prominences of either side do mutually grow together as it were with wings stretched out one to another; but for as much as it is behoveful for those grow∣ings together to be distingushed from the oblong marrow, therefore an hollowness comes between, which is by some esteemed the fourth Belly, and by others a passage to it. These prominences in a Man, Dog, and Cat, and some other Animals (as was above mentioned) are very small, and almost even; also they appear, as the other portion of the oblong marrow, of a white colour. In a Calf, Sheep, Horse, and many other four-footed Beasts, the former protuberances, commonly called Nates or Buttocks, are re∣markably great, also outwardly they appear to be of a flesh colour, because they are cloathed with the thin Meninx or Pia Mater, which contains in it self very many Veins and Arteries; which if separated, the interior substance of those parts is of a wannish colour, and such as is not in all the oblong marrow or pith besides. But it plainly ap∣pears, as in Brutes, so in Man, the hinder or posterior prominences are Epiphyses or additions of the former, and that from these additions or dependences the medullary processes ascend obliquely into the Cerebel; near which, other processes cutting those, descend direct from the Cerebel, which seem not to be inserted into the medullary Trunk, but going about it, do constitute the annulary or ringy protuberance. This annulary protuberance is greater in a Man than in any other Creature. Besides, it is observed, that where-ever the superior prominence of the Buttock-form is larger, this inferior annulary is very small; and so on the contrary. Further, those medul∣lary processes, ascending towards the Cerebel, communicate mutually among them∣selves by the other transverse medullary process; and out of this transverse process, two small little Nerves arise, the fourth pair of those which we have recounted, and which are called by us Pathetical. Each of these, delineated in fit figures, the se∣venth Table shews clear enough.

Not far from the aforesaid Prominences, to wit, between these and the Chink, which is called the Anus or Arse-hole, the Pineal Glandula or Kernel is placed. This is put in a Valley, which lyes between the Natiform protuberances, and those which are the Chambers or Thalami of the Optick Nerves; in which place that Glandula or Ker∣nel is fixed, sometimes by very many small Fibres, and sometimes by two noted me∣dullary roots subjected to the part; and besides, it is included in a Membrane, which is a portion of the Pia Mater, as in a Chest; and as this Membrane is stuffed with very many Arteries and Veins, some small Vessels also enter into this Glandula.

Under the Prominences but now described, (as was above hinted) a narrow Ca∣vity or Ventricle is stretched out with a long passage, which, although it obtains some egregious uses, yet it self seems to be only secondary, and as it were by chance; for that the processes of either prominence ought to be conjoyned among themselves, and to be distinguished from the under-lying medullary Trunk. Two holes lye open into this Trunk, one of which is placed in the beginning, and the other in the end of it, and through the middle of its passage the down-bending aperture tends towards the Tunnel; so that the serous humor entring at either hole, may presently slide away into the Tunnel. Moreover, into the same aperture of the Tunnel there lyes open another passage, to wit, through the first hole, which is placed near the roots of the Fornix; so that from every quarter of the Head the serosities might be carried into that sink: to wit, that through the first hole, from the infoldings or the anterior Ventricles of the Brain; through the second hole, the humors which are gathered about the orbicular prominences, do come away; and through the third hole, those

which are laid up high the confines of the Cerebel, do find a passage. These several holes, with the distinct ways to the Tunnel, are plainly delineated in the seventh Table H. M. T.

Above the Pineal Kernel, as it were above the Button, the infolding of the Cho∣roeides seems to be hung; now this infolding is made after this manner: out of either side of the oblong marrow, where the border of the brain is knit to it, two Arteries arising from the posterior branches of the Carotides, where they are united to the Ver∣tebrals, do directly ascend; which being presently divided, like many Rivers planted near together, are carried towards the pineal Glandula, and there seem to be termi∣nated by a mutual meeting: and in that place, out of the fourth bosom, sent down upon the pineal Glandula, the veinous branches come out on both sides, which in like manner being divided into filaments or small threads, meet with the capillary or hairy Arteries, and are in many places inoculated into them, and variously com∣plicated with them; and so these Vessels, being Net-like, much interwoven among themselves, and interserted with the Glandula's, do constitute the to be admired in∣foldings. These kind of infoldings of the Vessels, as it were with two out-stretched wings, are thrust out on either side upon the shanks of the oblong marrow, even to the streaked bodies; but yet they only lye upon their superficies, nor are they more firmly affixed either to the oblong marrow, or to the callous body by any insertions of the Vessels; so that the blood seems only to be brought to these places, and carried away without any afflux of it made into the subjected parts; for what uses shall be spoken of hereafter. The Choroidal infoldings, with the pineal Glandula, are drawn out in the seventh Table G. F. E.

And thus far concerning the appearances found above the oblong Marrow, between the streaked bodies and the Cerebel; which indeed are almost constantly after a like manner both in Man and four-footed Beasts, unless that they only differ in bigness. Within this space, in the Pedestal or Basis of the same Marrow, many things worth noting occur: For besides the ends of the cut off Vessels, which are above recited, the site and structure of the Infundible or Tunnel deserve consideration. For behind the coalition or joyning together of either Optick Nerve between the shanks of the oblong marrow there gaping, is sent down a receptacle as it were tubulated or made like a Pipe, covered without with a thin Membrane arising from the Pia Mater, and defended within with a medullary substance. The orifice of this is placed higher be∣tween the shanks of the oblong marrow, and receives their bending aperture; from thence a short Tube or Pipe being sent down, is inserted to the pituitary Glandula or Kernel. We see this Tube in an Horses brain greater than a Gooses quill, also shi∣ning and full of clear water; that it is not to be doubted, but that by this way the serous humors slide away from the brain to the pituitary Glandula: but how these humors are carried away from thence, shall be afterwards inquired into, because they are not carried into the Palate or roof of the mouth, as is commonly believed.

Nigh the lower border of the Tunnel, in a Man, underneath there are two whitish Glandula's; though in Brutes only one, but greater, is found. What is the proper use of this part shall be told hereafter: in the mean time, whether it be doubled or only one larger, it seems to be as it were instead of a bank to defend or preserve the thin Membrane of the Tunnel, lest it should be broken or thrust out of its place: on the other side the growing together of the Optick Nerves serves instead of the same kind of defence.

What besides is contained in this space are only the shanks of the oblong marrow it self, which proceed directly from the chambers of the Optick Nerves towards the hinder part of the Head in a straight passage; and when both grow together below the Tunnel, they are afterwards distinguished in their whole tract by a line drawn through the midst. These shanks of a mans brain are far larger than in brute beasts: to wit, in that they seem to be made up of very many medullary chords or strings joyned to∣gether in one, as if in this common passage and high-way of the animal Spirits, they were so many distinct paths, which the Spirits enter into respectively, according to the various impulses of sense and local motion. Moreover, this space of the oblong marrow therefore appears shorter and more broken in a man, because much of it is hid by the annulary protuberance, which is sent from the Cerebel, and is very big. The Pia Mater, all about covering the sides of this medullary Trunk, cloaths them with most thick infoldings of the Vessels; by which heat and the nervous juyce are carried, as a continual provision for the Spirits, taking a long journey. Thus much

for the first Section, or anterior portion of the oblong marrow: now our order car∣ries us to the inspection of its hinder Region, to wit, where the Cerebel grows to it; and the Processes sent from this either compass about its Trunk, or are inserted into it; out of which also, the other Nerves produced within the Skull, take their be∣ginnings. Concerning these we will speak in order.