oblongata, growing out of the Brain. But Riolanus de∣monstrates, that they are turned round about those great Eminencies of the Brain, which G•••••• c••••s Thata••os ner∣vorum opticorum, which reach unto the foremore Ventri∣cles, that they may fetch optick spirits from thence.
And having proceeded a while, they are neer the middle way united above the saddle of Os Sphaeno••des, not by a simple touch or intersection, in Man∣kind, but a total confusion and min∣gling of their Substances, that they might suffer the less, in the middle of a long passage, by reason of their softness. Vesalius, Aquapendens and Val∣verda have observed that they have somtimes continued divided, in their whole Course. Vesalius also observed that in a Woman they were joyned only by mutual Con∣tact, whose right Eye had been withered from a Child; because the right Nerve was smaller than the left, beyond the Conjunction. But in most bodies the inner substance of the Nerves is confounded, as I have observed by accu∣rate Inquisition.
The growing together of the optick nerves, was therfore contrived by Nature, either left the sensible object being received in by both Eyes should seem double, or that the Visive spirit might, if need were, be all conveighed into one Eye which are the conjectures of Galen, or finally for strength and stability here necessary, least in Concussions of the Brain they might hap to be broken or distorted, or least through the softness and moistness of the Brain and optick Nerves, by reason of distillations and other Excre∣ments they might become flaggie, and so driven out of their right station; which is the opinion of Plempius.
Soon after being seperated they go out of the Skull in∣to the Centre of the Eyes in Mankind, but much lower in Beasts, because they look more sidewaies.
Within the Skull they are cloathed only with the Pia mater; but from the holes, which pass to the Eyes, they are covered with the dura mater. Afterward it spreads the latter to the Sclirotica tunica, the former to the Tunica cho∣roïdes, and its inner marrowy substance to the Retina.
The third pare, which others count the second, is the motorium oculorum, the Eye-mover, next unto the former.
This pare is thought by vulgar A∣natomists to arise from the Brain, neer the original of the first pare. But it reaches to the middle of the Head, goes beneath the Opticks cross-wise, and
Arises at the inmost part of the Beginning of the medulla oblongata, where in their Rise, these two mo∣tive-nerves are so united as to touch one another, yea to become one continued Body, which is the cause, that when one Eye moves, the other is mo∣ved also.
This Pare is lesser and harder than the former and stretched out by the visive pare; goes out of the Skull at other holes to the Muscles of the Eyes and Ey∣lids. It sometimes though seldom sends a branch to the temporal Muscle; and that is the Cause that the said Muscle be∣ing hurt, the Eye is hurt, and the Eye being hurt that is hurt.
The Fourth, Fift and Sixt pares are much confounded by Anatomists. For some make the fourth and fift Pare one, and call it the third Pare, consisting of two roots; the lesser of which some do make the third pare, and they themselves do make the fift and sixt pare one, viz, the fourth pare by them so called. But those who reckon it for one, they count the fourth pare, according to my rec∣koning, for the lesser root of the third pares and the sixt pare for the fourth. whereas we distinguish all these pares.
The fourth pare therefore, which others as Bauhin•• count the third; others as Fallopius the eighth pare; o∣thers badly, the lesser root of the third pare: for it hath nothing common with the following pare, is not joyned to it, either in the Beginning or the Progress, and grows out of the order of other pares •• according to some
From the side of the Beginning of the Medulla oblonga∣ta; according to others it grows with a very small Nerve, out of the lowest and hinder seat of the Medulla Cerebri or marrow of the Brain: then it is carried forwards, and fastned to the second pare, it goes with it out at the com∣mon hole, enters the socket of the Eye and sends one from it self branches
Into the fat of the Eye, the fift Muscle, and by a pecu∣liar hole of the Bone of the Fore-head, it goes out to the Skin of the Fore-head, and the upper Eye-lid. And these are furnished by its first branch.
The second furnishes the Muscles of the upper Lip, and some of the Nose, and the Lip it self and Gums.
The third by the Cavity of the Nostrils serves the coat of the said Nostrils.
The fourth serves the inner part of the temporal Mus∣cle. All which branches Fallopius doth attribute to the two following Conjugations: but my distribution is pro∣pounded by Vesalius, Columbus, P••uerus, and Bauhinus.
The fift Pare, which others count the thicker root of the third pare; is commonly thought to furnish the Tongue with the sense of Tasting.
This arises neer the following Conjugation, out of the sides of the Medulla oblongata, and presently after its pas∣sage through the Os sphenoïdes, a writhen branch comes out like a tendrel of a Vine (which some think is done to make it harder) and is united with two little twigs of the auditory Nerve.
It furnishes the Muscles of the Face, the Temporal Muscle, the chewing Muscle of the Cheeks, the Skin of the Face, the Gums and Teeth (for by their means the Teeth have all the sense they have) the Muscle that lies concealed in the mouth and the lower Lip.
The sixt pare, which some call Quarta Conjugatio, others the smaller root of the fourth Conjugation,
Hath a smaller Original, next the former, and somwhat harder than it.
It goes through a common hole with the former, and yet it doth not there∣fore become one pare with the former: for the third, fourth, and seventh pare, as I reckon them, do also pass through one and the same hole.
It is carried into the Palate. Others would have this pare also to serve the sense of Tasting.
The seventh pare, which others count the eighth, others the ninth, others the smaller portion of the fift pare, when as in the mean while it is a peculiar pare smaller and har∣der than the fift, also distinct therefrom in its original and progress:
For it arises a little before the fift commonly so called, in the middest of the Medulla oblongata, and going over the third pare, and cutting the same, it proceeds along between the third and fourth pare, where it is carried up∣wards and forewards, towards the sides.
It goes out of the hole with the third and fourth pare, and is commonly quite spent upon the Musculus abducen•• of the Eye. But that is a question, which others say, that it is carried into the temporal Muscle, and into that which lies concealed in the Mouth.
The Eighth pare which others count the fift, which is called Auditorium, the Hearing pare, arises close by the sides of the former, only a little below. It enters the Os petrosum, and is divid••d into the greater branch, which be∣ing spred out, they wil have to make the Drum, and the lesser broad below, as if it would accompany the sixt Con∣jugation.