Mikrokosmographia a description of the body of man. Together vvith the controuersies thereto belonging. Collected and translated out of all the best authors of anatomy, especially out of Gasper Bauhinus and Andreas Laurentius. By Helkiah Crooke Doctor of Physicke, physitian to His Maiestie, and his Highnesse professor in anatomy and chyrurgerie. Published by the Kings Maiesties especiall direction and warrant according to the first integrity, as it was originally written by the author.

CHAP. V. Of the vessels of the Eyes.

FOr the same reason for which we intreated precisely of the Muscles of the eye in their Historie, we will also handle their vessels more districtly in this place, and passe them ouer more lightly in the booke of Vessels. * 1.1

The vessels therefore which are sent vnto the eye are veines and Arteries, to which are added Nerues, as being cōmon Organs no lesse then the other. The Veines which are sent vnto the eye proceed out of the iugular Veines & leade blood for their nourishment.

The Arteries arise from the Carotides or sleepy Arteries, and are dispersed through the muscles to moderate the inward heate, and to sustaine their life; through which Mus∣cles * 1.2 as also through the fat they are accompanyed with Nerues, and distributed through their Membranes, which is shewed in the third Table the second and third figures at^h.

The Nerues are of two sorts, Optici and Motorij, that is, seeing and moouing; they * 1.3 proceed out of the marrow of the braine yet remaining within the scull and making the spinall marrow.

The Opticke Nerue [tab. 2. fig. 1 and 3. ^x. fig. 5. Λ. tab. 3. fig. 2. 4. 8. α.] which is called Visorius or the Nerue of sight, is on each side one, and these are amongst all the nerues of * 1.4 sense the largest, the thickest, the softest, and Galen also saith the longest in the third chap∣ter

of the sixteenth book de vsu partium. They are of a rare texture cōpassed with both the Meninges. [tab. 3. fig. 2. ^{a b c}.] They are the greatest and thickest of all the Synewes, that * 1.5 so aboundant faculty might be transported to the eye, that it might sooner haue sense of the light, and be manifold wayes affected.

They are very soft saith Galen in the fifth chapter of his seuenth book de placitis, that they might be sooner affected because they are nerues of sense and of a sense so very ne∣cessary, for all sense is perfected by receiuing and suffering. They are softer then any o∣ther, * 1.6 because they are affected by the light alone, which they receiue also very much bro∣ken. They are the longest of all the rest, because the way is long from their originall to the Orbe of the eye. Their texture is rare and thin, and therefore Herophilus beleeued that they were perforated: and Galen thereupon called the 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉 and meatus visorios. For in the third chapter of his sixeteenth booke de vsu partium, hee noteth out of Herophilus, * 1.7 that they are in their inside perforated all along their passage, and that perforation was the reason why they were made so large.

By these Galen thinketh not onely that the faculty of sense is transported, but also the Animall spirits in which the faculty is established, that so their sense might be more aboundant and strong: whereas through other Nerues he conceiueth that the vertue or faculty onely is carryed as we may perceiue in the 12. chapter of his tenth booke de vsu * 1.8 partium, and in the fifth chapter of his seuenth booke de placitis. These Opticke nerues in their end and in their originall are distinct, but at the middle of their progresse aboue the saddle or seat of the wedge bone, before they fal out of the scul becoming a litle broa∣der, the right is vnited with the left [tab. 21. lib. 7. fig. 1. ^oo.] so that they make the forme of the Greekeχ, not by cleauing the one to the other, or by intercussation, or that one rideth ouer the other, but by perfect and absolute vnion and confusion of their marrowes they are so ioyned that one cannot be separated from the other, [tab. 21. lib. 7. fig. 1. ^H] for it is a very rare thing in Anatomie to find them separated.

The vse of this coniunction is, partly that the Pupilla or sight of the eye might look vp∣pon the same plaine least otherwise the visible obiects should appeare double because * 1.9 the eyes are double: partly that the Idea or formes of visible things might be vnited and so the faculty of sight be common to both sides, because the visible spirit may passe from one eye to another in a moment for the more certainty of the sight: And this is prooued if we presse or inforce one eye vpward or downward, for then all things appeare double: wher∣fore as it was conuenient that the eyes should be pararels; so also the nerues, which be∣cause of the motion of the eyes might decline from the right line, especially seeing the muscles do compasse them and cleaue vnto them: for when one muscle onely whether is be the vpper or the lower is moued, the eye also is rowled to one side. And therefore Nature hath worthily ioyned the Opticke nerues together, that euen in such motions the faculty might be wholly conuaied to either side. And this appeareth to be true because if you put your hand betwixt your eyes along the length of your Nose, so that you cannot see the obiect you intend with both eyes, you shall perceiue that you see more obscurely on either side, then if you lookt vpon the obiect with one eye shut vp, for then the faculty which was before dispersed vnto both, is vnited into one. Adde also this third profit of the coniunction, that the soft nerues hauing a long way to go, might thus be made strong ande stablished, because Nature could not sustaine them with any ties or knots of Mem∣branes. After their coniunction they are instantly disioyned, and each nerue issueth through the proper hole which is framed in the depth of Orbe out of the scull [Tab. 21. lib. 7. fig. 1. aboue^H.] and so the right attaineth to the right, and the left vnto the left eye, and there are implanted.

In a man they are inserted on the backeside into the center of horny coate [see the third table fig. 2. 3. 4. 8.] because onely man can look directly forward. In brute beasts as in oxen and horses, whose eyes are much farther a sunder, they attain by a line notably oblique vn∣to the compasse of the eye and do not determine in the Center. Hence it is that the eyes of brute beasts doe see the earth on either sides to direct their gate and to finde out their nourishment. These Opticke nerus when they are come vnto the eies are dilated saith Ga∣len in the 1. chap. of his 10. book de vsu partium and like a membrane each of them in cō∣passe the glassie humor Galen also addeth in the same place that they are inserted into the Cristalline humour. * 1.10

The vse of these Opticke nerues is to leade the visible faculty from the braine which in

the eies is gathered vnto the visible formes, where the Nerue is dilated into the Mem∣brans of the eie. For if this Nerue be obstructed as it is in that disease which the Arabians call Gutta serena the cleare drop, the action of seeing is altogether taken away or inter∣cepted. * 1.11 And so much concerning the Optick Nerues.

The Nerues of Motion are on either side one, which sendeth a small surcle to eache Muscle by which it is mooued [Tab. 2. fig. 3. 4. sheweth this] (as he may perceiue who di∣ligently * 1.12 shall separate the beginning of the Muscles from the Nerue) which also is spred abroad into the Membranes. These moouing Muscles in their originall are continuall, that is, the right is ioyned with the left, whence it commeth to passe that when one eye * 1.13 is mooued the other also followeth the same motion: for they proceede ioyntly out of one point as it were in the fore-part of the spinall Marrow, so that the same obiect and the same light, after the same manner and at the same time insinuateth it selfe into either eye, that the sense and discerning might be one and the same; and this maketh much to the perfection of the sense that one and the same thing might not appear double, which doubtlesse would happen if one eye might be mooued vpward and the other downward at the same time. That this is true you may easily learne if with your finger you either * 1.14 depresse or lift vp one of your eyes, for then all obiects will appeare double, one higher another lower. But if you mooue your eye toward the side, because the pupilla or Sightes are in the same line, the obiects will not seeme double. Wherefore Galen in the thir∣teenth chapter of his tenth booke de vsu partium writeth, that the Diameters of the visi∣ble Cones must be placed in one and the same plaine, least that which is one do appeare double.

Hence it is, that in the palsye and convulsion of the Muscles of the eye the patient often seeth double Obiects, because the eyes do depart from the same plaine. So also when the Opticke Nerues are either conuelled or relaxed the pupilla or Sight not beeing in the same line, all thinges appeare double, which also for the same cause happeneth of∣tentimes to men when they are drunke.

From these Instrumentes Veynes, Arteries and Nerues are deriued vnto the eye; a∣boundance of Spirits Natural, Vitall and Animall, which are properly called visible spi∣rits: * 1.15 wherfore acording to the plenty of the Spirits conteyned in the eyes, their magni∣tude as also their splendor or brightnes is greater or lesse. And hence it is that whē men are nere their death their eyes becom litle, languid & obscure, as also those that do too much follow venerial combats haue their eyes smal and extenuated, so also wee see that in liuing men the eyes are full and turgid, but when they are deade they become lesse as also laxe and rugous, for the presence and absence of the spirits maketh a difference be∣twixt a liuing and a dead eie.

Againe, according to the diuers disposition of the spirites and of the eyes from them, * 1.16 we are able by our sight to distinguish and iudge oftentimes of the affections of the mind, which is a cleare argument and euen liable to our sense, that the body of a man is ful of spi∣rits, which thing Galen also in the tenth booke de vsu partium prooueth by an elegant and demonstratiue argument. For (saith he) if vpon the closing of one eye you do attentiuelie marke the pupilla or sight of the other, you shall perceyue it in a verie moment to be dila∣ted, because a greater quantity of spirits do fall into the Grapie coate which we call Vuea, through that coate which is called Reticularis or the Nette, where they dilate the hole of the Vuea, which hole is properly called Pupilla or the sight and Apple of the eye. Finallie, that the eyes are full of spirites is hence conuinced, because they are sometimes obscure, dull and languid or weake, sometimes bright or shining, quicke and apprehensiue. But least these spirites which are of an admirable finenesse and subtiltye might exhale or eua∣porate they are kept in and retained by a thick, thight and strong Membrane which is cal∣led the Horny coate.

Notes

• * 1.1

  The vessels are hete fully handled. Veines.
• * 1.2

  Arteries.
• * 1.3

  Nerues.
• * 1.4

  Opticke.
• * 1.5

  Why the grea¦test and thickest.
• * 1.6

  Why softer.
• * 1.7

  Galen out of Herophilus.
• * 1.8

  Where they are distinct. Where vni∣ted.
• * 1.9

  The vses of their coniun∣ction.
• * 1.10

  The vse of the optick nerues
• * 1.11

  Gutta serena.
• * 1.12

  The Nerues of motion.
• * 1.13

  Where they are continual
• * 1.14

  Demonstrati∣ons heereof.
• * 1.15

  The spirits of the Eies.
• * 1.16

  Diuers argu∣mentes to proue there are spirites in them.