Brain bear an over-proportion to the Trunks from whence they come and consequently must according to the aforesaid observation of Malpighius in his Letter to Fracassatus receive the blood brought thither far more freely and plentifully Besides the Cervical Artery here is so far from being Conical that being made up of two vertebral Arteries joyning together it is much wider than either of them single as appears plainly in the Figure FIG 1. g. and consequently would have carried away the Blood forwardly from the Spinal Artery more freely had not Nature order'd the Structure of Vessels after another manner here than it does in other parts of the Body where there is not the same necessity of contrivance One more Branch I take leave to mention only upon the score of its never hitherto having been taken notice of by any and that 's a small Artery attended with a Vein passing through the lateral part of the Os Cuneiforme which constitutes the back part of the Orbite of the Eye just under a very little Process of that Bone which either by reason of its size hath escaped being seen or inconsiderable use was never before as far as I know thought worth the mentioning and this upon raising the fore Lobes of the Brain offers it self to the Eye of any heedful Observer CHAP. V. Of the Sinus's belonging to the Brain A Third sort of Vessels offer themselves next to our consideration under the general name of Sinus's These formerly were reckon'd only four to which Vesalius added a fifth at the bottom of the Falx Vesal p. 758 Fig. 3. F. by him only call'd a Vein which tho' frequently found yet in some Subjects is wanting Bourd p. 105. par 2. Bourdon mentions two more at the bottom of each side the side the second Process of the Dura Mater under the lateral ones which I never saw but once and I am apt to think with Vieussenius are most commonly wanting Vieussenius describes four more Vieuss p. 6. par 5. Fall tom 1. p 114. Vid. Vid. p. 117. cap. 10. p 310. cap. 11. which I find long before taken notice of and exactly describ'd by Falloppius and after him tho' but rudely by that laborious Collector Vidus Vidius I think I can shew one more but be their number what it will I judge it reasonable to look upon them no other than Veins whether we consider them in respect to either Office or Structure All the business is to consider and shew for what end they appear as such large Channels into which all the Veins of the Brain like so many small Rivulets after an unusual manner do empty themselves and that I will endeavour to do after having first shown their several respective situations The first two are called Laterales FIG 4. BB. which run within a strong duplicature of the hinder Process of the Dura Mater down upon the Os Occipitale over the Cerebellum till in their further descent after a tortuous manner upon the lower production of the Ossa Petrosa they wind under them in order to their passage out of the Cranium at the eighth hole FIG 2. CC. common to the eighth pair of Nerves going out Ibid. bb the third Branch of Arteries belonging to the Dura Mater and the internal Jugular coming in which is through two round bony Cells in the Os Petrosa Ibid. L. just under the Styloeid Processes into the internal Jugular Vein into which together with the Vertebral all the rest of the Veins and Sinus's belonging to the Brain discharge the refluent Blood The next is called the third or longitudinal one FIG 4. AA c. from its rise at the bony Process called Crista Galli and progress the whole length of the Brain to the hinder and somewhat declining part of the occipital Bone where it seems to be cleft into the two lateral ones Into this third Sinus not only the internal Veins of the Brain it self are inserted but also some of those belonging to its outward Integuments which Falloppius first Fallop tom 1. p. 82. par 3 Vitus p. 10. par 2. Weps p 42. par 2. one of the Luminaries of Anatomy observed and after him Vieussenius which are by Wepfer mistakenly taken for Arteries who nevertheless for ought I know may be in the right in assigning the overcloseness of the Pores of the Cranium by what Accident soever happening thro' which the refluent Blood is transmitted to the Sinus for a frequent cause of inveterate obstinate Headachs The fourth FIG 4. C. which from its situation may not improperly be called the Internal Sinus comes from the under part of the falcated Process at that point where it becomes continuous to the second Process of the Dura Mater Ibid. II. and a large double Vein belonging to the Plexus Choroeides together with the fifth Sinus Ibid. K. when there is one enters it at an Interstice made between the end of the Corpus Callosum the Nates Testes and Cerebellum from whence having first passed over the Cerebellum it at last arrives with the other three at that place of union which from its Author hath ever since retain'd the Name of Torcular Herophili Ibid g. The four others of Falloppius and Vidus Vidius or Vieussenius by this last called Superiores and Inferiores the dd first two of which being longer and narrower are call'd Superiores are on the Basis of the Brain * FIG 2. dd arise according to him from the Receptacula Sellae Aequinae by the same Author so named hereafter to be described though more truly from the ee circular Sinus Ibid. EE as I hope in its place to make appear running down from thence upon the internal Process of the Os Petrosum and terminating in the Sinus Laterales where they begin to be declive and λ tortuous in their passage to the internal Jugular Ibid. λ. The other two called ee Inferiores Ibid. ee which are much shorter and wider than the others descend from the same place as the former between the Os Petrosum and Occipitale down to the aforesaid eighth hole of the Cranium where the Jugulars come up into the Brain and end there Another I discover'd by having first injected the Veins with Wax running round the Pituitary Gland on its upper side forwardly within a duplicature of the Dura Mater backwardly between the Dura Mater and Pia Mater there somewhat loosely stretched over the subjacent Gland it self and laterally in a sort of a Canal made up of the Dura Mater above and the carotid Artery on each outside of the Gland which by being tasten'd to the Dura Mater above and below at the Basis of the Skull too leaves only a little Interstice betwixt it self and the Gland thereby constituting a Cavity communicating with the two foremention'd forward and backward ones from whence the abovemention'd four small Sinus's do descend by a visible continuity
dispersed thro' Bourd p. 196. par 2. it so forcible as to create a sensible Systole and Diastole in its outward coverings 'T is worth noting that while the Blood-vessels are all full so as to keep the Dura Mater upon its full stretch the pulsation is not vi sible at all or at least very faintly but after a depletion of the Vessels so as that grows somewhat more lax the beating becomes very visible equally in the Sinus and Membrane too After having made this Experiment I found one Author of the same opinion and that is Falloppius who in vindication of Galen against Vesalius his Contemporary says all I have said upon the foregoing Experiment and all the great Vesalius was able to answer in his own vindication in his ingenious Book call'd Anatomicam Gabr. Falloppi Observat Examen falls very short of its aim As to the Transverse Ligaments which are in some places * Fig. 4. r. round cordal and in others †Ibid. x. broad or membranous in the Longitudinal Sinus chiefly both serving for Strength and in concurrence with the cruciform ligamentous Fibres taken notice of by Vieussenius on the under and outside of this Sinus from whence the Fibres belonging to the falcated Process aforemention'd seem to have their original Elasticity to this part for its more vigorous reduction of the Blood passing through it together with its blind Cavities or Diverticulums serving to moderate the over-swift or violent motion of the Blood seeing I find them so exactly describ'd by Vieussenius to whom the Reader may have recourse I think their description need take up no room here But as to the manner of the Veins entring this Sinus I find it far different from that which is describ'd by Lower first Low fig. 4. h h. Vituss tab 2 D D c. and afterwards by Vieussenius both whom make them enter with their Orifices from behind forwards two or three only excepted by Vieussenius and that for some other useful purposes than what have hitherto been taken notice of And this is as follows Fig. 4. dd c. viz. About one half of them tho' intermixedly but all after having first upon their arival at the Sinus insinuated themselves for some space alter the manner of the Pancreatick Duct or Ureters first taken notice of by Lower Ib. dd c. betwixt the Duplicature of the Dura Mater from behind forwards the other half from before backwards as in the Figure Now by this contrivance 't is plain that first of all there are made two contrary Torrents in one and the same Channel by which means the refluent Blood made poor by the vast quantity of its richest parts drawn off as it were into Animal Spirits thro' a collision of Parts which by this contrivance must needs fall out is preserv'd in its due mixture which when at any time lost through the languishing of its intestine motion or elasticity retards even its circular or progressive motion which when it happens but in some degree is the cause of many Distempers and when altogether of Death it self In the next place the circulation is at all times not only somewhat retarded and the Blood hinder'd together with the help of the bony Cell at which the internal Jugular Veins enter the Sinus's especially in an erect posture from descending with that rapidness and weight it would otherwise have done upon the descending Cava to the Heart but also much more so retarded in a supine position of the Head a posture most natural and ordinary for Mankind to take their rest in through which contrivance in concurrence with that of the Lateral Sinus's whose structure is such that in the aforesaid posture the Blood is forced to climb upwards before it can arrive at the place of its descent into the Jugular Vein there is made a more plentiful generation of Animal Spirits one chief Cause of the great refreshment and vigorous disposition of the whole Body we find after Sleeping As to the other manner of the Veins entring this Sinus viz. from before backwards it from thence happens that in a prone Position of the Brain a posture not uncommon amongst Men the Blood is help'd forward in its circulation through the Sinus the truth and design whereof are at once both evident and pointed at by Nature from the Structure of this part and which therefore shews the great usefulness of Comparative Anatomy in Brutes who by reason of such a Position which the necessity of Feeding almost always keeps them in have always such a disposition of this Part to assist the Blood in its heavy circulation The design of Nature in making these Channels so wide on a sudden in respect to the Branches of Veins lately treated of terminating in them seems to correspond with the conformation of the Parts just now treated of and with that it had in making the Ramifications of Arteries afore taken notice of so large and unproportionable to the Trunks from which they spring which is a flower than ordinary circulation of Blood through the Brain in order to make a still more copious production of the Animal Spirits so called Which profitable Design and End of Nature had nevertheless been attended with a very great Inconvenience viz. an extravasation of too much Serum the usual effect or consequence of a slacken'd Circulation had it not been for another provident Contrivance of Nature in the two Communicant-branches betwixt the Carotid and Vertebral Arteries aforemention'd p. 36. by the narrowness of whose Channel the influent Blood is in some measure represt in its motion and an overcharging the Vessels with Blood prevented These Sinus's differ in structure one from another the Longitudinal and Lateral ones having many transverse Ligaments which the other have not and the Longitudinal having many small Cavities or blind Diverticulums as aforesaid which the Lateral have not the use of them all being for strengthening and defending them from giving way to the violent irruption of Blood into them against which sometimes notwithstanding they are not able to defend themselves as I have seen in many Skulls ni which the Blood hath burst open the sides of the Sinus's and found its way between the Duplicature of it so as even to have made a Fovea or Cavity in the Cranium it self as was before noted one of which I have now by me CHAP. VII Of the Plexus Choroeides THIS Plexus is an aggregate Body made up of Arteries Veins Membrane and Glands double on each side which hath not before been taken notice of and consequently having two Originals The first Original is from the foremost Branch of the Communicant Artery FIG 1. ee which running backward up betwixt the hinder Lobes of the Brain in which for some part of the way it is immerged and to which it gives many large Branches and the Medulla Oblongata at length arrives at the Lateral Ventricles FIG 5. ee and makes one part of
together with almost all the Ancients as Vesalius Columbus c. to the contrary I have never found this Rete wanting or with any difficulty discoverable in Men springing from and lying on the inside of each Carotid Artery in that place of the Circular Sinus chiefly which looks into the four abovemention'd inferiour and superiour Sinus's in the Basis of the Brain and in some measure also the whole length of the Sella Turcica on each side between the Gland and the Carotid Artery And that it is so small in them with respect to what it is in Brutes of several kinds is no way surprizing when consideration is had to the Use and Service of it in those Creatures who by reason of their prone Position would otherwise be in danger of having their Brains deluged as it were with an over-great quantity of the Influent Blood and of a Rupture of the Vessels by its violent ingress and this Danger so much the more threatned by how much the same Cause which brings it into the Brain with that force is equally as great and effectual to hinder its proportionable return for the relief of which Inconveniency Nature hath contriv'd a means of its more easie and safe descent into the Brain by turning that one large Stream of Blood which through its being penn'd in one Channel becomes so rapid into many more by which means the Carotid Trunk above the Dura Mater in those Creatures is very small to what it is beneath whereas that Artery in Men c. hath the same bigness on both sides that Membrane and they not only reticulated and contorted for the more slow and laborious which Contrivance the Ancients thought was only for a more exact preparation of the Blood for Animal Spirits descent of the Blood but also many of them by their insertion into the Glandula Pituitaria attended with small Veins issuing thence to take off some part of the burden too This last contrivance of Nature methinks may be sufficient to render that Controversie of Vieussenius with Willis which before them Vieuss p. 16 pat 2. was bewixt Waleus and Rolfincius the two latter on each side denying this Rete to have any Veins very needless feeing that if the Pituitary Gland have any which I am confident it hath notwithstanding the positive Assertion of Diemerbroeke Diemerbr p. 364. par 3. in order to serve his own most unprobable Hypothesis to the contrary as having seen them plain injected with Wax then this part of the Blood in some of the Branches of the said Rete which are plainly inserted into the Gland is equally capable of being reduced by those Veins without any necessity of having recourse to those remote Branches Vieussenius hath been forced to seek for Vieuss p 45 par 2. as if it had had them of its own And that to the aforesaid Position of different Creatures ought chiefly to be ascrib'd the variety of Magnitude of this Rete in several of them its size in Dogs seems highly to evince in which by reason of their Horizontal Position being neither so prone as several Brutes who seed on Grass nor so erect as Man that Rete is found smaller than in the first and larger than in the last Another Use it hath been thought to have is to carry off a considerable quantity of a dull watery part of the Blood in order to the production of the finer Animal Spirits and this it is thought to effect by means and help of the Pituitary Gland betwixt which and it self there is constantly observ'd a greater affinity the one being either greater or lesser in proportion as the other is so and betwixt which there are in all Creatures but more remarkably in those where they are both large a distribution of several Branches coming from the aforesaid Rete And this is look'd upon by Vieussenius so considerable an office of the Glandula Pituitaria that in those Creatures where it is but small as in Men Horses Dogs c. he hath substituted many Vieus p. 102 par 3. but particularly two Cavities for that use in the Wedglike Bone just under the Sella Turcica in which he supposes that part of the aforesaid Serum which by the smallness of the Rete cannot be return'd that way is remitted by several little Arteries slipt off from the Carotid whilst under the Sella Turcica terminating in the two abovenamed Cavities there either deposing a part of the Serum to be carried off by a strange way he there mentions viz. by two holes into the Nostrils and thence into the Fauces or else by certain Veins meeting them in that place as their proper Reductory Vessels Vieuss p. 9. par 2. to the Heart Now as to this office of the Glandula Pituitaria I cannot easily be perswaded it is either design'd for or capable of it till such time the Abettors of this Opinion can be able to show me it furnish'd with an Excretory Duct for this purpose And if they offer that the Veins are such I reply That besides its being very unprobable that so vast a quantity of Blood as continually is brought by the Carotid Arteries to the Brain should be able to get rid of any considerable quantity of its Serosity by so small a part as the Glandula Pituitaria is 't is not the usual way of Nature to part with any Share of its Juices out of its Vessels when so unactive and unprositable as this is and immediately to receive it in again seeing it is provided of Emunctories enough to convey it away by Moreover granting which by no reasonable means is to be granted it were so as they would have it yet nevertheless in conformity to Nature's proceedings in all such-like case there ought to be an intermediate passage by way of a Secretory Duct which none hath been able hitherto to discover And so far as Vieussenius seems to be of this opinion Vieus p. 102 par 3. which in one place he plainly is making it of so gross and viscid a nature as is only sit to be discharg'd at the Emunctory of the Nose the same Reply is satisfactory But when by way of flat contradiction to himself he comes to make the same gross Humour a perfect fine Lympha the Answer is then Vieuss p. 54. par 1. That there is no need of parting with it beforehand seeing we find that Liquor only separated by the Lymphaeducts of the Brain afterwards Seeing therefore there is such an affinity as before mention'd between the Rete Mirabile and Glandula Pituitaria and taking it for granted that the office of the Glandula Pituitaria is not what it hath generally hitherto been believ'd to the end we may attain a more exact knowledge of what it really is it seemeth not altogether immethodical to take that part into consideration in the next place together with the Infundibulum which last hath not only as near a relation to the Gland as the Gland
hath to the Rete but such a close communication with it that it seems in a manner almost impossible to treat of one independently on the other CHAP. IX Of the Glandula Pituitaria and Infundibulum THIS Gland is seated in and fills up in a manner all that space contain'd within the Sella Turcica Vessels only excepted 'T is cover'd on all sides with the Pia and Dura Mater excepting that part on its upper Superficies in which there is a little round hole by which the Infundibulum descends slopingly into it being at its entrance inviron'd with a Production of the Pia Mater for its more firm connexion with that part as was before noted But as to the Dura Mater it encompasses it after a far different manner than what Vieussenius hath describ'd Vieuss p. 51 par 5. not suspending it in Man as it doth in Brutes so as to hinder it from touching the bottom of the Sella and that forasmuch as there is not the same reason for its so doing in one as there is in the other for in Brutes the Rete Mirabile is not only situate on each side this Gland but runs quite under its hinder part by which one side of the Rete communicates with the other a Disposition of this Part which Vieussenius was altogether unacquainted with whereas in Man inasmuch as there is not that sort of Structure in the one i. e. the Rete 't is not nccessary it should be requir'd in the other However in neither one nor the other is the Reason which Vieussenius gives for Nature's contrivance of this affair of any weight seeing neither the Rete Mirabile Vieuss p. 50 par 1. much less the few small Veins belonging to the Bone beneath could possibly any way be compressed by this Gland though superincumbent because it is so firmly knit to the Dura Mater lying above and upon it which is supported by the two foremost and hindermost Processes of the Sella Turcica in such a manner as is sufficient to sustain and keep from pressing upon any subjacent part ten times a greater weight than the Glandula Pituitaria is Moreover the Dura Mater is so far from suspending it from that Bone that it is together with the Gland fixed to that very Bone it self The substance of this Gland is far differing from that of all the rest which I have often upon this account particularly examin'd in consistence indeed 't is the same with most of the Conglobate kind if not somewhat harder but then being pressed or squeezed it emits much more Water than any of them As to the Conglomerate sort it hath not the least resemblance to any of them and consequently cannot be suppos'd as it hath hitherto been by all to carry off any excrementitious or unprofitable pare of the Blood Now if we consider this part together with the appended Infundibulum we shall certainly find a conformation far different from any other part in the whole Body of Man inasmuch as that which this Gland receives by the Infundibulum or which is the same what this Infundibulum conveys to it is not separated from the mass of Fluids by any visible Secretory Duct which in its ordinary method Nature is observ'd constantly to make use of whensoever it parts with any part of the Blood whether excrementitious or reductitious throughout the whole compages of the Body Nor hath the manner of Nature in transmitting a certain Liquor to the Gland been less abstruse in carrying it off from that part again the reductory Vessels from the Gland being equally conceal'd as the adductory to the Infundibulum that way of Transudation according to the invention of Vieussenius being to the greatest degree improbable as having no resemblance to the course of Nature throughout the whole Body Nay even a possibility it self seems hardly allowable if we take but notice of that part in Brutes in whom its Integuments are extraordinary dense the Dura Mater as he truly observes investing it close on every side and which he perceiving and consequently foreseeing what might from thence unanswerably be objected against him was forced to make them much more than in Men in which last indeed there is seemingly some reason for its being so Vieuss p. 52 par 2. inasmuch as the Rete lies in a Duplicature as it were of the Dura Mater on each side of the hindermost part of the Sella Turcica as tho' one Lamina of it was spread upon the subjacent Bone and the other over the Pituitary Gland a disposition contrary to that in Brutes as hath already been taken notice of but nevertheless there is no necessity that it should be so divided in this place nor doth the said Author ever offer a Reason for its being so which looks as though his Assertion was only a Guess seeing this Membrane can send out new Productions as well double as single as we find in its two eminent Processes before describ'd and Sinus's agreeable to what it also therefore may and does do here where the Integuments of this part appear plainly to be of too thick a consistence to admit of his imaginary way of transudation which is manifest not only by sight and section but in that by the greatest force made use of in compressing and squeezing it between ones Fingers we find it impossible to force out the least appearance of Humidity through its aforesaid Inclosure or Integuments Being therefore very inquisitive after the true use of this part and despairing of ever attaining to such a Knowledge without first knowing the exact Structure thereof besides all other means commonly made use of in all Anatomical Enquiries I made use of all sorts of Injections serviceable to such an end as of tinged Liquors Wax and Mercury but all with little if any success according to my expectation the Wax not penetrating its Texture at all the tinged Liquors but very superficially and the Mercury where my chief Hopes were always by its weight do what I could to the contrary either breaking through the sides of the Infundibulum where it leaves the Brain or else falling down in greater Globuli than the extream narrow Passages were capable of admitting and by this means became altogether useless Being compelled therefore for the present to leave off a little while a further enquiry into the Structure of this part by reason of the great mist it is involved in and to gain a little more Light for our Guidance in searching after Truth which like many other things of greatest value lyes deep and is with great difficulty accessible it may not be amiss to see what Assistance can be had by making diligent Scrutiny into the Structure of its Appendix the Infundibulum The Infundibulum This is a thin medullary Duct covered with the Pia Mater descending from the internal Concave Superficies of the Brain to which by reason of its wideness towards one end and narrowness towards the other in resemblance to a
to make my self a Party on either side at this time seeing the fineness of structure and dignity of functions are sufficient to give preference to one above another and to render it more worthy of a particular consideration And this part I take to be the Brain the delicacy of whose structure is such that with no little resemblance to its divine Author whilst it gives us the greatest and clearest discoveries of other things lies most concealed it self And seeing all that Mystick Knowledge which in ancient times in the eyes especially of the Vulgar appeared meer Necromancy or Witchcraft as well as all the Curious Discoveries of more modern Ages upon the whole subject of Nature now going under the more familiar and proper term of Refined Sence or Philosophy hath been meerly owing to a more acurate knowledge of the parts and modification of Matter I see not any more likely way of conquering the difficulties yet behind upon any particular subject than the endeavouring after a further and more nice scrutiny into it by such means and experiments as serve to bring its most minute parts and texture under the test of Sence which so assisted doth the same office to the discerning faculty at good artificial Glasses do to it bringing the Object and Judgment to such a nearness that even the first Link of the Chain becomes discernable and the mechanical proceedings of Nature so highly instructive to the Understanding in its finding out and assigning proper Causes to Effects much more obvious and intelligible I shall therefore treat this Noble Part after the aforesaid manner with all the Justice I can leaving those invisible and almost divine things called Animal Spirits to be treated of more at large by those more illuminated Philosophers who see best when their Eyes are put and content my self with making an inquiry into and giving a description of whatsoever upon this Subject by Dissection shall offer it self as an Object of our Senses THE ANATOMY OF THE BRAIN CHAP. 1. Of the Anatomy of the Brain THE topmost part or Olla of the Cranium being removed the first part of the Brain that comes in view is the Dura Mater which with the subjacent Pia Mater is accounted only an improper part of the Brain strictly so called however of great use in many respects to it 'T is by Spigelius and other Anatomists reckon'd and I think not undeservedly the thickest and hardest Membrane of the whole Body enclosing the whole Brain properly so called somewhat losely sticking almost inseparably to the Basis of the Cranium and to the top and sides under the Coronal Sagittal and Lamdocid Sutures very fast by the Sinus's whose description will come in another place In some places of the upper part of the Cranium which on each side of the Sagittal Suture or Vertex are called Ossa Bregmatis it adheres not to the Bone notwithstanding the positive Opinion of Van Roonhuyse Roonh p. 149. in his Leiter to Du Foy to the contrary who for that very reason would fain take away in a great measure the use of the Trepan and Trefoyne and altogether the use of the Instrument called Decussorium which skilful Surgeons do often make use of to make room for the discharge of subsided matter below the fractur'd place in many Accidents of the Brain 'T is very discernably double as Columbus and several others formerly Col. p. 348 and Vieussenius lately have observed having very strong and large Fibres on the inside but very small Vienss p. 3. and hardly visible on that side next the Skull as appeared to me after having first let it lye a little time in bolling or at least very scalding Water But as to the distribution of the double sort of Fibres on each side this Membrane I could not by any means find them agreeing with the description Vieussenius hath given of them as running in an oblique semicircular manner externally from before backwards and in the same figure internally from behind forwards but far otherwise on the inside where they are very strong they seem manifestly to have three originals from the top part of the Processus Falcatus before behind and in its middle those before running in a curved manner backwards half the length and a great width of the Dura Mater and those behind running after the same manner forwardly with this difference that a great number of them bend soon after their rise from that process in a kind of a semilunary way to it again a little on this side the rise of the middle Series of Fibres others of them making a bigger arch after having stretched themselves wider upon the Dura Mater bend back again to and terminate in the Falx a little beyond the rise of the aforesaid middle Series of Fibres Those from the middle part of the Falx run backwardly but less curved than the rest terminating as the Fibres which arise backwardly do at some distance from the Process in the inward Superficies of the Dura Mater As to those belonging to the exernal side or second Lamina of the Dura Mater they are extream small and obscure running from behind forwards Besides these there are no less remarkable ones belonging to the Falx it self of two sorts of Orders the one running streight about half the length of it on its upper part from before backwards the other transverse from the inferiour or fifth Sinus to the superiour or third on the hinder part of the Process and are most conspicuous there as the other are towards its foremost part As to the Use of those Fibres it may be remembred that this Membrane consists of two Lamina's between which the Veins which reduce the Blood from the Arteries which furnish the whole Brain with it run for some space after the manner of the Ureters in the Bladder in large Trunks before they enter the Sinus so that the Fibrous Constitution of this Membrane here where the Blood-vessels are largest together with the curved entrance of them into the Sinus especially in an erect position of the Body do the office of Valves support the weight and promote the ascent of the Blood But that which is most considerable is this That if the inward Lamina of this part which makes the inferiour and lateral part of the Sinus was not in some measure furnish'd with additional strength on this side suitable to that which it hath on the other by reason of its cohesion to the Skull the Blood which is continually running through it with no small rapidity especially in great plenitude of the Vessels or preternatural Ebulitions would frequently burst out or at least cause such distentions as could not but be very injurious to a part so very exquisitely sensible yet notwithstanding tho' Nature seems plainly to have made a double provision against such Accidents by the transverse Ligaments within the Sinus and these strong and numerous Fibres without I have rarely open'd any strangled Body where some
Arteries unless the Arteries they accompany discharge their Blood into the Sinusses which as hereafter shall be shown they plainly do not for otherwise seeing they both grow capillary in their ascent from the Basis of the Cranium they must necessarily be both adductory Vessels than which by the Laws of Circulation there can be no greater an Absurdity Wepfer not knowing of these Veins was forced to think and consequently to affirm That the Arteries leave the Dura Mater in their extremities and terminate in the Pia Mater and so have their Blood reduced by the Veins there but this is evidently not so to the Eye of any who heedfully separates this Membrane from the other Before therefore I proceed to the description of the Blood-vessels belonging to the Brain it self which by the exactness of method I ought to do I hope it may be pardonable if I make a short enquiry after the unaccustom'd distribution of Blood-vessels Nature hath furnish'd the Brain in general with and the Reasons of its procedure therein The Truth then concerning this affair is That contrary to what hath hitherto been observed the Blood-vessels belonging to this part in general as hath already been observed are of two sorts the one belonging to the Brain it self the other to its outmost Integuments Now as to the first 't is observable that the Veins enter not the Brain nor run concomitantly like as in other parts of the Body with the Arteries the carotid entring at the fourth hole in the Basis of the Skull and the internal Jugular at the eighth the Vertebral Artery at the last and largest hole of the Skull and the Vertebral Vein at the ninth which Vieussenius mistakenly calls the tenth thro' which it runs into the internal Jugular Vieâ—ssen p. 163. par 3. at that Veins entrance into the round hole at the bottom of the Skull under the Styliform Process where the Sinus Lateralis meets it where after having advanc'd into certain venous productions called Sinus's they descend from thence in large Trunks growing capillary all-along in their passage till they meet the Extremities of the Arteries and are indeed no other than meer Branches of the Sinus's and consequently I look upon the Sinus's themselves no other than large Veins The common reason all modern Authors give for this different distribution of Blood-vessels belonging to the Brain from the other parts of the Body is that it may receive an equal warmth at the top as at the bottom as being thereby very much assisted in the production of Animal Spirits in an equal proportion all over and that it is so may very well be granted but that Nature had yet another provident Intention will be as evident if we consider that if the Veins had ascended with the Arteries thro' the holes in the bottom of the Cranium upon all great Ebulitions of the Blood the pulsation of the Arteries would in that Stricture of the Vessels made by the Bone of necessity hinder the freedom of its return by the Veins and consequently occasion a stagnation of Blood through the whole Brain to the utter subversion of all its faculties nothing being more certain than that upon any considerable abatement of circulation there presently happens by way of restagnation a secession of the watery and thin from the more gross and red part of the Blood The other way of the Veins entring the Brain viz. those appertaining to its outward Integument one at the sixth hole of the Basis of the Cranium the other at the eighth as aforesaid is their ascent with the Arteries after a quite different manner from the former even to their capillary Extremities a manifest indication that they serve for the reduction of so much Blood from the Dura Mater as the aforesaid sort of Vessels the Arteries have brought thither and although by reason of their smallness Nature seems not to have been so sollicitous in avoiding the Inconvenience supposed to have follow'd upon the Artery's entring the same hole with the Veins taken notice of in the preceding Case where they are very large and consequently the Effect might prove much more injurious yet Nature hath not been wanting in providing a Remedy against it as will plainly appear in the following Pages From this manner of their entring the Brain at the same inlet of the Skull with the Arteries may for ought I know be very rationally accounted for that violent troublesome Noise which many in Distempers arising from the turgescency of the Blood causing a preternatural beating of the Arteries do so much complain of a Symptom happening from the Stricture before mention'd which the unyielding circumference of the Bone occasions upon the different Blood-vessels entring at one and the same Foramen to which effect also the nearness of the Os Petrosum through which the Hearing Nerves do pass to this hole which is in that part of the Wedglike Bone that joyns to or is conterminous with it does not a little contribute To the same cause in some measure doubtless may be ascribed the frequent Headachs happening in Feavers the Artery then so swelling and compressing the Vein against the edges of the Bone that the Blood cannot be returned back through it in a due proportion and consequently by its stagnation the Membrane becomes inflamed and painful So that conformable to what hath already been taken notice of concerning the wise contrivance of Nature in ordering the different distribution of the Blood-vessels so as to avoid the Inconveniencies which might accrew to the Brain by compression of the reductory Vessels occasion'd through their entrance at one and the same hole with the Arteries it seems very much worth our observing that besides the Veins of the Dura Mater which enter the Cranium together with the Arteries as hath before been mention'd there are also several others belonging to this Membrane having their rise at and their descent after a very remarkable manner from a Vein hereafter to be describ'd on each side of the Longitudinal Sinus as you may see in the Figure FIG 4. dd nn c. and consequently must grow capillary in their descent down from it after a quite contrary manner to the other and these do visibly inosculate with some of the Extremities of the aforesaid capillary Arteries after the same manner as those larger Veins belonging to the Pia Mater do with the Arteries belonging to the Brain and it by which means it so falls out that a considerable part of that Blood brought up by the Meninx Arteries is carried back by these Veins to the end that especially in all preternatural swelling of the Blood the inconvenience of Compression and all its ill consequences happening by reason of an overfulness of these Vessels may be in a great measure avoided CHAP. IV. Of the Veins belonging to the Brain it self AFTER this short digression by order of Method the Blood-vessels belonging properly to the Brain it self fall under consideration The curious
Anatomist Malpighius Malp. de Cereb p. 6. par 2. De Cort. Cereb p 81 par 2. in his Letter to Fracassatus says they bear a third proportion to those of the whole Body and for what reason seeing seeing the part it self bears not the same proportion to the whole it is so it will be worth our while to enquire hereafter These are either Arteries or Veins The former go under the name of Carotid and Vertebral The first of which after a curved passage which is very well expressed in a Fig. Willis p. 29. Fig. 1. of Dr. Willis from the place where it begins to enter the Basis of the Cranium which is from the Styliform Process of the Os Petrosum to the place where on the inside they pass through the Dura Mater and ascend into the Brain which is at the foremost internal Process of the Os Cuneiforme there is very near an inch and an half distance I say after this crooked passage into the Brain they are propagated quite through its substance having first divested themselves of that thick Coat borrowed of the Dura Mater during their stay in the passage aforementioned but not without the mediation or intervention of the Pia Mater which Membrane all the Branches of the aforesaid as well as the Vertebral Artery more or less first prop themselves upon before they enter on and disperse themselves through the substance of the Brain it self and is very finely expressed in a Cut of Placentinus Sig. p. 179 Mol. p. 77. Marchetti p. 191. par 5. at the end of Spigelius insomuch that Molinetti with whom also agrees Marchetti looks upon it as only a production of those numerous Vessels whereas all those little ramifications both of the Carotid and Vertebral Arteries viz. those from the carotid Artery which as soon as it gets through the Dura Mater and parts with its borrowed Coat are sent to the a Vieussen p. 35. par 1. p 34. par 6. Infundibulum b Tab. 17. c c. Olfactory and c Ib. g g. Optick Nerves together with those other of the Vertebral Artery which accompany pany the d Vicussen p. 35. par 1. third e Ibid. fourth f Tab. 17. p p. 35. par 1. fifth g Tab. 17. TT Tab. 4. sixth h h. p. 35. par 1. seventh i Tab. 17. Fig. 2. Tab. 4. h h. eighth k Ib. Fig. 2. ninth and l Tab. 4. h h. tenth pairs of Nerves inasmuch as they enter not the Brain it self are altogether exempt from that Membrane any of which now-mention'd Blood-vessels you either find delineated in Vieussenius's 17th Table or mention'd in some other place of his Book by those Directions here placed in the margin all which tho' existent in Nature are nevertheless there painted too stiff and formal I am afraid by guess inasmuch as that without an injection of Mercury except those two which belong to the Olfactory and Optick Nerves they do rarely come to sight in any form at all Wax being over gross a body to enter such minute Vessels as those are whereas by an injection with Mercury I find scarce any Nerves but what hath some such small ramifications of Blood-vessels in them To go about to describe distinctly the whole ramification of Arteries through this part which as was before noted is here more remarkable for number and size than in any other part of the Body would not only be to do what in a great measure hath been already done by Vieussenius in his sixth Chapter but seem to have also in it much more of oftentation than use I shall therefore only take notice of such propagations of them as are either remarkable for magnitude some curiosity of Structure or useful design of Nature And of this sort may well be esteemed the Vertebral Artery next after the Carotid which hath already been described as entering the Brain at the last and largest Foramen of the Skull contrary to what Dr. Willis Willis p. 29. col 1. par 2. and before him Wepfer affirms coming thither on each side out of the hole in the transverse Process of the first Vertebra of the Neck after a very remarkable curved manner as you see in the Figure Fio. 1. Eâ— and by no means like to the delineation and description given by Dr. Lower and Dr. Willis ascending laterally upon the Medulla Oblongata as far as the beginning of the Processus Annularis where they meet together in one single Trunk continuing so the length thereof Vieussen Tab. 4. bb by Vieussenius call'd Arteria Cervicalis after which they either send forth two Branches or receive two from the carotid Artery by means whereof there is a communication betwixt these two large Blood-vessels and that of great use and benefit to the Brain for by this means it happens that if even three of the four great Arteries which furnish this part with Blood were totally obstructed there would yet be a way left for a competent supply from the other unobstructed fourth These I call the Communicant branches very ill pointed in Bidloo's ninth Table but very well in Vieussenius's fourth as may plainly appear here in the Figure taken exactly from Nature it self FIG I. dd The structure and sinallness of these Arteries seem to suggest two yet further provident Intentions of Nature The first is the same it hath expressed in several other places as in the ascent of the Blood by the Carotid Arteries both which enter the Brain in a crooked line the first at the fourth hole of the Basis of the Skull the second from the hole in the transverse process of the first Vertebra of the Neck after the manner already in both places described So in the like manner here by the narrowness of these Branches the Blood is in a great measure retarded in its motion to the carotid Artery and by consequence to the Brain it self which for Reasons hereafter to be given in describing the Sinus's would otherwise be in great danger of being overflowed with extravasated and restagnant Blood The second is a forcing the Blood more plentifully into the Spinal Artery with which tho' through the conical structure of the Arteries in common it cannot be altogether unfurnish'd yet by its perfectly-reflexed position would have it very scantily were it not that by reason of the narrowness of the aforesaid Communicant-branches betwixt the two great Arteries the Blood was driven back in a sort of a retrograde motion 'T is true there is a conformation of Arteries something like this tho' not altogether in the mammary and epigastrick Branches but 't is worth noting that in both these places the main Artery from which these Branches spring is much more taper or conical Ibid. p. c c and the succeeding exporting Vessels far less both in number and size than those of the carotid Artery here whose foremost and hinder lateral ramifications between the Lobes of the
is that of Instinct relating to the Sensative Soul or an aptitude of the Nervous Structure to act according to the Impressions made upon the Nerves either from within or from without and so may be said to depend on the presence of such Causes as are supervenient and extraneous to Nature suitable to the impressions whereof the Animal either pursues or avoids the Object obeys or resists the Impulse Now I take it for granted that no body will deny but that the Nerves by vertue whereof these last actions of Instinct are performed whether thâ—y â—râ—se from the Cerebrum of Cerebellum are equally under the command of the Soul or else as I said before the Brain in those Creatures is to no purpose And of this sort I reckon all those actions in rational creatures of Instinct before they have attain'd to the use of their Vnderstanding from any sort of Impressions or inadvertent and inconsulted when he hath the controuling power of Reason allow'd him and makes no use of it such as are called Habitual which at first were produced by command of the Rational Part only but through frequent repetitions at last without any command from that out of a blind obedience to a bare impulse from the Object or lastly such as happen when he hath altogether lost the use of it as in Sleep or Distraction in which last Cases 't will be very difficult to distinguish him from a meer Machine or Automaton Now from what hath been said I cannot but think it plain that many of the Actions before spoken of in Dr. Willis's sence by him called Involuntary as proceeding from the dominion of the Cerebellum only such as he calls the various Configuration of the Face from some Impulse or Provocations in the Viscera or elsewhere erecting the Ears turning the Neck and Eyes about sudden Shrieks and Outcries upon some extraordinary frightful Object surprizingly affecting one Sense or another furnished with either such Nerves as he supposes to be altogether under the command of the Cerebellum as the fifth and seventh or else to have a very near correspondence with that part by vertue of Vicinity as the ninth do more truly proceed from that perceptive faculty or to use his own words that part of the Soul he hath confin'd to that part of the Medullary System called the Cerebrum inasmuch as in reasonable Creatures they may and commonly are suspended as well as the Nerves they slow from sometimes made use of as Instruments of Voluntary Motion by it also and to think the contrary is as much as to say that when any body happens to express any of the aforemention'd involuntary Acts or but hit his Bedfellow a box of the Ear whilst asleep all these must be allow'd to proceed only from the Organ of Involuntary Motions called the Cerebellum And of this kind also in a great measure I reckon Respiration concerning which I cannot easily be brought to think it satisfactorily explain'd by Dr. Willis from the Energy of those Animal Spirits which flow only from the Cerebellum in the Par Vagum after the same manner they do to the Heart by the Intercostal and that Pair for its pulsation and as only under the command of the Soul to be stopt now and then as it pleases by vertue of some Nerves communicated to the Intercostal Muscles and Diaphragm the chief Instruments of breathing from the Spina Dorsi I am therefore rather enclin'd to think this Motion is of the other different kind before spoken of under the Title of Instinct proceeding from an extraneous supervenient Cause acting conformably to the course of Nature in oother Cases of the same kind as in Hunger and Thirst and the like where the obtaining the designed End or Effect renders the part from whence comes the Motion for some time insensible of the impression and where after the ceasing of the Effect or Motion the sense of the impression revives again whence there happens an equal reciprocation between the Sense and Fruition or Sense and Motion To apply this account of the manner and reason of the Spirits acting upon the Stomach and Parâ—â—te in relation to Hunger and Thirst to that of the Systole and Diastole of the Lungs or Respiration 't will be needful to take notice that in an Infant unborn there is no Respiration but yet there is a Cerebellum and that if this sort of Motion called Instinct which I make to differ from purely Natural Motions such as are contemporary with even the first living Rudiments of the Individual was altogether and solely owing to the Cerebellum after the manner of that of the Heart then of necessity the Child in the Womb ought to respire But being satisfied of the contrary it remains that we account for its respiration another way which is as afore noted through the presence or absence of the first moving Cause or Impulse which I make or suppose to be any thing impressing the Nerves propagated through the Organs of Breathing so as to transmit the impression from within to the perceptive Faculty presiding both over the Cerebrum and Cerebellum too to the end the Spirits may from thence forthwith be commanded into such other Nerves as act those Muscles which serve for enlarging the whole Cavity of the Thorax in order to let the Air into the Lungs more plentifully which was the thing aimed at by Nature and these are the Intercostal Muscles and Diaphragm Now 't is easie to conceive that whilst the Child is enclosed in its Mothers Belly there is not that occasion for Respiration as when 't is born the main Stream of Blood all that while finding no passage thro' them and that which does by the Ruyshian Artery made of Juices much more mild and cooler the native heat being little and the Aliment meer Chyle or Milk from whence it falls out that the Pulmoniâ—k Nerves go altogether unprovoked which after birth are continually otherwise impressed or provoked by the hot Effluviums of Blood new bred of stronger Food and by a stronger native heat and wholly flowing through them which heat continually as the Child acquires a greater maturity encreasing may for ought I know not a little contribute by way of natural impulse to its exclusion The truth of this will the more clearly appear to any who will take the pains to consider well of the structure of Parts in Children unborn in whom the usual circuit of Blood through the Lungs which are designed for rarifying and perfecting the mixture of Blood and Chyle is denyed as also through the Liver serving chiefly for separating that gross Excrement the Gall not bred at least in any proportion in an Infant unborn and in lieu of these other Passages which become altogether unnecessary after birth provided by Nature after a shorter and more compendious way viz by the Foramen Ovale betwixt the Vena Cava and Vena Pulmon and Tubulus Arteriosus between the Art Pulm. and Aorta in the Lungs and
resist Death as to turn it self from the inverted or supine position it had been placed in in order to make the Experiment to its prone or natural one and to live and move six hours after From whence it appears that Muscular Motion is capable of being performed by the Animal Fluid alone without the concurrence of the Blood by most Authors constantly hitherto made to go a share therewith in the performance of that action Caldesi p. 75 76. So that we find Nature hath not stinted it self to one place for the Seat of the Sensative Soul or Reservatories of the Animal Spirits so called in order to the discharge of the afore-mention'd Functions no more than it is at a loss about the maintaining them in their Integrity by other ways when it hath so fallen out that the natural structure of the Organs destin'd by Nature to that end have utterly been destroy'd of which we have many Instances in the Anatomical History those Functions in several Creatures remaining perfect where after death there have been sound neither any Cerebrum or Cerebellum at all or at least such as by their constitution was utterly render'd useless to any such end Of the first is an Instance of the Learned Wepfer in a Child living sixteen hours alter it was born and discharging all the Duties of Nature that one of its age was capable of and by tho by which all the patrons of a nutritious Juice by the Nerves may do well to take notice of of a very strong and good habit of Body Misc Câ—ries Av. 3 p. 120 whose Brain after death was found to be only an heap of Watery Bladders or Hydatides except a small part at the bottom of the Skull lying in a Sinus made in the Wedglike Bone where the Pituitary Gland is commonly found consisting only of three Medullary Bodies two of which being each of the bigness of a Kidney Bean and the third behind them of a Pea only from which indeed there did proceed some but very inconsiderable Nerves or Nervous Fibrils but such as none can judge of a due proportion requisite to satisfie the Exigencies of the common natural and vital Functions The truth of which is still more plain and without exception in another Instance in the Miscell Med. Physic Gallic of a Child living sive days after it was born Misc Med. Phys Gall. Au. 3. p. 54. whose Head had nothing but Water contained within the inclosures of the Dura and Pia Mater without the least footsteps of any medullary part at all Parallel to which two last Instances I had one communicated to me by that curious Anatomist and learned Person Dr. Tyson in a Child born alive with no more Brain in the Skull than what might lye in a Filbird-shell the Medulla Spinalis being much larger than ordinary as though part of the absent Brain had been squeez'd down thither Of the last viz. where the natural conformation hath been depraved there is extant an Instance in two several places of the Miscell Curios in a sat Ox Misc Cur. Obs 26. 130. An. 1. which while living there were observ'd but very little signs of any such thing whole Brain was nevertheless after death found wholly petrified From all these 't is manifest the Sensative Faculty is able to answer its internal or external Impressions by one part as well as another and that the Medullary System of the Spinalis Medulla may become as adequate a Sensory in relation to the aforesaid Functions sometimes as either Cerebrum or Cerebellum And as to the power or influence the Soul in general exercises over the Nerves howsoever different in their original seeing we have already observed what a provident care Nature hath taken for the preserving Creatures from their own violence in that it hath not only constituted the chief Fountain from whence the great current of Spirits is derived for the service of the vital and natural parts by the Eighth and Intercostal Nerves which is the Cerebellum so as to be free from the commands of the Rational Will in its ordinary way of acting but hath also taken care that not any of those Branches which have their originals from Trunks which are under the power of voluntary dictates of the Soul should terminate in such Organs by which those Functions are discharg'd abare communication between Nerves of different Provinces not being sufficient to such ends or offices as hath been observed in those afore-mention'd additional subsidiary smaller Streams of Spirits flowing to the parts consecrate to the natural and vital Functions by Branches propagated from the Spinal Marrow to the Intercostal Nerve all the way of its descent to the lower Venter So we may further also remark that as there are some manner of Impressions made upon the perceptive Faculty after such sort of a manner as that it even loses its power over its own Subjects viz. the Nerves which are subservient to its voluntary commands as in Laughing Sneezing and libidinous Erections the Organs by which these Actions are produc'd being altogether under the power of those Nerves subservient to the voluntary dictates of the Soul and acted after the very same manner as those of Respiration as often as preportionable objects present and notwithstanding the assertion of Dr. Willis to the contrary who makes Laughing proper to Man only and by the authority of Aristotle Sneezing an Affection proper but to few if any other Creature besides Man might also produce the same effects in Brutes Will p 106 provided their stupid Souls were capable of being equally impressed by such Objects as arc proper for exciting a rational Laughter as we see they are by those producing the aforemention'd venereous actions of the want of the Plexus Cervicalis of the Intercostal Nerves and two or three small Branches propagated from thence to the Nerve of the Diaphragm which he calls a Disposition peculiar to Man and consequently in his opinion the cause of that Affection in him might be in a great measure supplied not only by that nervous Branch we find propagated from the interioâ—r Plexus of the Par Vagum which Nerve is equally dependent on the Cerebellum as the Intercostal to the third Brachial Nerve from which the Nerve of the Diaphragm hath one of its originals but also that other propagated from the Thoracick Plexus of the Intercostal Nerve it self to the same aforesaid Brachial Nerve into which the Nerve of the Diaphragm is inserted So on the contrary there are some Impressions made upon the Soul sometimes through which it acquires a power over those Nerves at other times in no wise subject to it and those are the impressions either of great Joy or great Grief suitable to which the Vital and Natural Faculties are made either much more or else so much less vigorous than ordinary as even quite to languish How this comes to pass according to Dr. Willis in savour of his own Hypothesis and