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that alters the blood, lymph, and matter of the spiriis, so thatthey cannot pass f ely through the arteries of the brain, but
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that as soon as the brain is cut, it loses the poWer of raisingilself; or even that is it be strongly compressed With the hand,so as to be forced to stop iis animations, the respiration of the iung8 ceases, though not the pulsation Of the heari, uniess Similar violence has been done to the cerebellum. Exactly the fame esse is Will be produced in a greater or less degree, is instead os the compression produced by the haud, either blood, lymph, hydatids, schirrus, or anything et se intrude upon the spaces betWeen the meninges, upon the Winding channeis belWeen thecortical substances, upon the interstices betWeen the medullarysibres, or into any of the other cavities that are to be dilatedand constricted in general or particular With the brain; or is
NOW Dom these considerations it appears, that the diagnostic Sigus Of compression, Obstruction, Or lesion Of the Cerebrum, Cerebellum, Or Spinal marroW, Will be more evident isderived Dom the respiration of the lungs than is derived Domthe pulsation of the heari; although it is bottor stili to derive thom si om both at orice; for the respiration os the lungs indi-
See also his Institutiones Medicin, n. 860.- Tr. 9
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cntes the peculiarities in tho transflux of the spiriis through thunerves; and the pulse of the hears, the peculiarities hi thotransflux of the blood through the arteries; consequently the
two logother indicate the effect With iis OWu real cause. IX. 5 I. That there is such a close relationship bet Neen the animations os the brain and body, that their moments are contem-pOIaneous, is a fact Whicli has not escaped the observation ei theros modern or of ancient anatomisis. But although they have tacitly admitted it, yet non e of thom have chosen to RVOW it Openly, and as I apprehend sor this reason, that in eaeli eXtremity of the animal body, tho heari manis esis iis presenee by iis pulsation; Whenco they have been led to thinii that no arteryhad anyWhere any other motion than that of the hestri itfel Whicli consequently they did not venture to deprive os universat Tule, CVen Over the brain, so far as regards the blood; and Stili tess When they observed the dura mater pulsating With Similar alternations. Dut I cannot help thini in g, that had thelearned once salion into the opinion, that tho brain took the
With in iis cranium Or osseolis fortross, they Would likeWise have been led into the opinion, that tho braitis animate When thel ungs respire. In deed, upon this opinion thoy had atready began to fouch, but could scarcely reconcile it With the preconceived opinion respecting the pulsation of tho heari extendingto the brains, and lience every one had recourse to his OWn particular method of reconciling the tWO motions.
Which We are surrounded, and of Whicli the mouth and nostriis are constantly fuit, is immediately continuous With the air that filis tho iubes and the tympanum, so it comes also into immediate contact With tho dura mater; and theres re according as thesume external air is Various, it is en abled also to exercise various
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of the ventricles and other cavities to an immense extent; SO RS necessarily to cause the body of the cerebrum aud cerebellum to fili a greater space, und in a manner to bo thrust OutWards.' erre, p. 9I; 4to ., Rome, I 741.) And Fantoni says: Τhis We clearly See, and detect by actual touch, in those Who have lost any considerable portiou of the situli by Wounds; and thesedegrees of motion are various according as the arteries beat gently or strongly, and ns their diameter is greater or less; andalso accOrding as the respiration is vehement Or the reverse. Epist. ad Pacchionum, in Ρacch. Oper., p. 17I, 172.)53. The reader Will be surprisod to find, that ouen Bagliviat last candidly moois the fame question among his ΡOStulates, in apparent contrariety to What ho had sald of tho motivo fibro in the dura mater; us though he wero doubiful Whicli side tofine. Sitico the dura mater,'' says he, is ulmost the solemistross of the motion of the liquids and solids in the livingbOdy, and in a manner has the govorument of the heari itfel ns We manifeStly perceive from the passions of the milid, thequestion arises, whether the suid molion of the dura mater be notpart natural and paris voluntary, that is to say, miled, like the molion of the respiratory oryans' see Ρari II., Π. 7J : Sothnt We can, at the command of the Will, Or as Our temporaryassections require, render the motion more Or less intense Orgentio, sitfed to express and propul a greater or less quantity of the nervolas liquid. See Ibid., Π. 8.J . . . And thus according to
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guments Which he adduces, he gratiis that the motion of the dura mater is partly volunta ; and honeo is not lilio that of the heari, Whicli is purely naturat, but like that of the lungs, Whicli is mixed. He goes on to say : The great degree OfpOWer and force exercised by the uir in quickening the motionos liquids during respiration, . . . may be Very clearly inferreiiDOm the follOWing experiment. . . . Tahe a mustiis, and fa8ten itto a table in the usual Way: then caresully malle an Opening in the throat, and 1u this Opening place a Canula So conStructed
we not suspeet that the fame force contributes in Some Wayto the mot1On of the dura mater, either by elasticity, Or Someother occult mechanical means 3 ke. O . Cit., Epi8t. in cap. V.)54. That the a1r 1nspired in respiration contributes to themotion Of the dura mater, Was long ago obscurely indicated by Galen, Lib. de Respirationis Oilitate, cap. v., ad sin.; and Lib. de Dogmatibus Hippocratis et Platonis.' φ It appears then that Our v1eW Was not Without iis Weight among the ancients, Onlythat a leader Was Wantium at Whose declaration a conclusionmight be formed frona the preceding facts and conceSSionS.
55. But perhaps you Will oppose to me the experience of thogrentest anatom1sis, Who by touch and sight have observed themotion Of the dura mater to be synchronous With that of thelieari or arteries of the body; for there is not one of them, Soar as I know, but has fallen in With this generat opinion. For
' Baglivi, De Fibra Motrice, lib. i., cap. V., in EpiSt.- Tro
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is you apply ille finger to the fontanelle in the insunt, you Willnotice a plain agreement belWeen iis pulses and those of thelieari; and What amounts to the fame in adulis also. Thus Baglivi says: In cases of WOunds of the head, Where the dura
mater has been luid bare, I have observed, on placing my righthand over the patienUs heari, that the dura mater pulsated atthe very Same time as the heari, nor could I detect any intervalbotWeen the pulsation of the tWO.V . Cit., lib. i., cap. V.)But although this excellent author calis the dura mater theheart of the brain,' Ibid., and maintains that iis motionis impressed upon it in the primordial stages of generation, by reason Of the peculiar structure Os iis fibres, Whicli is notvery unlike that of the fibres of the heari, Ibid., cap. V. in Epist. and although he is supported by ait this eXperienee, never-theless he foems to be divided belWeen tUO Opinions, and to fluctuate toWard the Other fide of the question, as appears hom thepasSages above cited, and aS Will appear further in the sequel. Ridloy telis us that, he Observed a systallic motion of the
tion of the hestri, Which Was qui clier than usual, aud exactly corresponding With it in potnt of time.V Ρari II., D. I.) Butit is Wolt to bo noted, that tho vibration of the heari Was found by this author to be more rapid thau the vibration of the dura mater 8 , or longitudinal sinus ; consequently a discrepancy intime Was Observed, Such as there is belWeen the motions of thelieari and of the lungs When compressed. Realdus Columbus
membranes, See the motion Of the brain. For the bratu moves in the fame manner as ali confess that the heari itself moves, namely, With a motion Os dilatation and constriction. De Re Anatomica lib. Xu.; lib. Xiv., de viva Sectione. But this Writer passes OVer the main potnt to be noticed, namely, Whether Orno the bratu dilates and constricis synchronousty With the heart. We noed malle no further citations. Those niready giVen arequite susticient to perplex the iniud, and render it unable easilyto take either One fide of the question or the other: but thething will bocome clear is We duly examine the miXed Or com- pound motion Os the dura mater.
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56. Here We may repent a former observation Ρari II.,
n. 2), that it is extremoly disticuli accuratvly to detect in livingsubjecis the distinct intervals of the elevation of the brain; sorunt ess the brain iiseu be presented to VieW, We Only pereeiVetho motion of the dura mater; and this motion is miXed, consisting of One motion 1 rom the arteries, and of another Domitio bruin received through the medium of the three sinuses; and hence We are deceived by sirst appearances. This is the reason Why Baglivi, Pacchioni, Vietissens, and ali the Other authors that I have hithorto consulted, deriving their information apparently DOm experience and autopsy, asseri that the rhythmS Orpulses of the brain and heari are concordant.
57. In the srst place, there is no question that under the
finger the dura mater receives a motion Dom iis arteries; sor ithas innumerable arteries, and Only a feW Veius, and theSe arer ected toWards the fides of the sinuses, Or their prOCOSSCS. These arteries of the dura mater immediately communicate Withthe arteries On the Oulside of the heud, and are sunt into the anterior and posterior part of the membrane, through their oWn proper foramina, as also through the spinous foramen of the
Sphenoid bone, through the foramen by Whicli the eighth patr
fig. 2, H, and through the carotic foramen, Whether the meningeat artery comes os Dom the carotid as a tWig, Or enterS RS an accompanying branch DOm the externat carotid, as the Same author seems to intimate : stili no arterv of this membrane ever arises Dom the internat carotid, after it onoe ascends thebrain, test the motions of the two fhould be conlaunded. Thus even after birili this internat periosteum maintains the Same compaci that it formerly enterest into With the externat periosteumor perieranium, and correspondes With it in a marked manner in the bratiis os insanis, and during inflammation, particularlynear the fontanelle, Where, joined to the periuranium in theremarkabie space belWeen the coronai and sagittat Sutures, andanteriorly by the frontal suture, and constructed Os an immense number of arteries confluent Dom both hemispheres of the dura mater, and communicating With the arteries on the oulside Os
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58. In the second place, iliat the dura mater is expandedand contracted by the subjacent brain, appenrS DOm itS CΟΠΠeetion With tho longitudinal and laterat sinuses, and with thelaurili sinus, and Doui the connection os these With the brain
by VeSSeis and membranous prolongations and cordes : and Domthe position of the sinusus themsolves in the duplicature of the dura mater, anil between the hemispheres anu brains : also Domthe oblique courso and inflexion of the fibres of the dura mater in exact agreemunt With the direction of the motion Dom the Circumseretice toWards iis centres : and Dom the Similar progre8Sion Os the cords : and Dom the insertiou of the litile vetus running into it Dom the brain tuto the sinuses in a manner Corresponding With the peculiar expansion and contraction Os thebrain : also DOm the common course os iis arteries Dom their origins Over the cerebrum and cerebellum toWard the DurthSinus, io Whicli the motions of the cerebrum and cerebellum themselves tend : and Dom innumerable other indications in thelabrio of the dura mater and sinuses. But it is even yet more evident Dorii autopsy; lar Ridley, having made an experimentupon a living dog, shews that the sinuses themselves have nopulsation Other than What is communicaten to them hom thesubjacent brain.' Anatomy of the Brain, chap. Vi., p. 50.ὶ Andagain he says, We SaW a systallic motion os the brain pro
the brain, so of courso must be the inner lamina of the dura mater, Whicli invests and surrouuiis the sinus, and is continuedinto the processes. And Ρacchioni says: The dura mater appears to me to have a mixed motion, namely, One motion ofconstriction and restitution; and another, Of elevation and depreSSion. . . . SO that the natural motion of iis circumferetice consi sis in a gentie and bland alternation os contraction und
says : The true systallio and compressive motion of the dura mater, is not mund On iis extortini sursace, but in iis centruand mi dille, abolit the falx and nil iis septa, Where the mem-
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brane is furnishod With strong lacertous coriis.' Dissertatio varii Aryumenti, cap. ii.) And Fautoni says : Although tho contractile motion is With more dissiculty seen in the head, yetit may be observed in the upper part Of the dura mater, RS
indeod it has been by various anatomisis, Who have olearly Wit-nessed the motions of this membrane, and have observed thatthey are dependent upon the motions Of the arteries and brain. Epist. cit. in Pacch. Oper., p. I 69.)59. Thus I thiuli it is evident, that the dura mater has amixed or compotand motion; that is tO SV, tWO motionS; One, pulsatile and sensibio to the to uch, corresponding With the vibration Os iis arteries; and another, expansite, coming Dom thewhole of the circumferetice Where the sinuses are Silualed, RIad Which lalter motion is not so perceptibie to the sense Of toueh. everthel ess that it dous exist, is evident not only Dom theproo1 8 above adduced, but also froin the extreme elasticity of the fibres of the dura mater, and their capacity of eXpansionanti contraction; from the duplication or triplication os iis strata Or laminae, betWoen Whicli the arteries ruti; and DOm tho tWO- solii discliarge of iis venous blood, Damely, either into the Sinuses through particular smali orifices, according to the observation Os WinslOW, E . Anai., Tr. de la Teste, Π. 36,) Orthrough the futures into the substance of the cranium, or ullthe Way to the pericranium, and somelimes through a particular ramen Dear the junction of the sagittat future with the lamb-doidal. And a similar discli argu of venous blood obtaius in thobody, Where tWO motions, as Of the heari and lungs, alternatetheir play; for example, in ali the intercostat vetris, Whose bloodis derived into the vena agygos at the times of the respirationS,as above observed Ρari II., D. 25-30); but at the other times, When the respiration is not determined thither, the blood is derived in to the inferior cava, sor the intercosials tend directlythithor also; c. Thus Ρacchioni says : The motion of the dura mater is not simply pulsatile, as ΜVoW and Others have thought:. . . for it is quite evident that this pulsatile motion is not the genuine motion of the dura mater, but is rather oWing to the brainaud to the arteries of the pia and dura mater,' e. erct, P.
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The motion of the dura mater . . . is composed, sirSt, of the constrictive motion of the Whole membrane and iis segmentSOver the cortex of the cerebrum and cerebellum; and secondiy,
of the resilient motion of the membrane to the internat parietes of the cranium, c. kc. Ibid., p. 92.) Aud Baglivi says : The motion Os restitution consisis in the relaxation of thesbres previousty on the stretch. Dissert. varii Aryumenti, cap. ii.) And again : TWo motions may be granted in paris of this Liud; one, procoeding DOm the membraues to the paris; the other, proceeding froin the paris to the membra es.' De Fibrci Motrice, cap. v.) So that ali Our authors Wondersullyngrue in the saet, that there are two motions in the dura mater: although euch of them has his own problem to defend; Baglivi maintaining that the systole and diastole of the heari dependupon the systole and diastole of the dura mater, Ibis, cap. V.): and Ρacchioni, that the dura mater is a membranous muSele Osa peculiar Lind. opera, p. 136; Ed. cit.) Stili, as I havesaid, they ali agree to the aliove opinion : sor as the dura mater vibrates at once With the heari and with the brain, it is in amanner the uniting medium os both their motions. And sorthis reason, be re the brain sentis Ofr iis vetus into the Sinuses, it transmits them into the borders of the dura mater, as ut Sodoes the spinal marroW,) Which borders depend immediatelyupon the motion of the brain. NoW DOm these considerations We may conclude, that the internat lamina of the dura mater belongs to the brain, the externat to the heari, and the middie, Where the arteries run, toboth; but With this qualification, that in infancy the lalter
belongs rather to the heari; in old age, rather to the brain; and in middie age, to both equally. For in infancy the numerous arteries of the dura mater clim , Over the sinuses beside theexternal or cardiae lamina, and the fontanelle ; in old age theyturn aside to the processes that are composed of the internat orcerebrat lamina; and this, to sueti an extent at last, When theessete or senile bratu gasps for breath and begitis to die, that the motion of the dura mater ceases to be mixed aud com
Dura Mater. 60. Nothing is more commou or beller known in nature Or