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. XXIII. Of the Nerue which ariueth at the Eares.

AT length we are come to the Auditory Nerue which maketh that coniuga∣tion which is commonly called the fift, [Tab. 21. lib. 7. fig. 1. 2. a. Tab. 15. lib. 7 fig. 20. M.] It issueth out of the tranuerse processe of the Cerebellum, and is * 1.1 a thicke and large nerue; therefore neerest of all to the After-braine because it was to conuey a great quantity of Animall spirits. It insinuateth it selfe into the first hole of the stony bone, which a large perforation and made of purpose with∣in the scull for the transmission of this nerue, which it hideth all the way it runneth for∣ward, till in the middle almost of the stony processe it is diuided into two vnequall parts: the one large & ample, the other small but harder; harder I say then the other, not through out the length of it, but onely in that part which is longer then the former. For, that wee * 1.2 may say so much by the way, the softnes or hardnes of a nerue dependeth vpon 3. things. First, vpon the originall, so those nerues that arise out of the Braine it selfe are the softer, those that arise out of the After-braine or out of the spinal marrow are the harder. Se∣condly, vpon their distance, as they are farther from their originall, or neerer vnto it.

So the Opticke nerues are the softest of the whole body, because they are neerest to their originall; the nerues of the hands and feete the hardest, because they are farthest off. Or, thirdly, it hangeth vpon their contaction: for frō their contactions with hard bodies as bones & gristles, or with soft as fat and vessels, they become harder and softer as Platentinus hath obserued, but this by the way. This slender production of the nerue through the vp∣per hole of the fore mentioned passage entereth into that secret bony canale which we cal∣led the Watercourse, and so creepeth toward the forepart of the head. Afterward it is re∣flected and entereth into the first cauitie, and falling downeward and backeward, it issueth out of the bone at the roote of the lap of the eare, and is subdiuided into three especiall branches. The larger and vpper runnes out into the foreside and the backeside of the roote of the outward eare. The lower deriued through the iaw, is distributed into the * 1.3 Masseter muscle and the first muscle that mooueth the cheeks. The third which is the mid∣dlemost is very small and Capillary, and is dissiminated into the glandulous and membra∣nous parts about the roote of the eare. There are also other threedy surcles which are * 1.4 spent into the muscles of the larynx or throtle, and of the bone Hyois. And this is the cause of the consent betweene the eares, the tong and the larynx. Hence also it is that when the auditory nerue is originally and in the first conformation obstructed, those that are borne * 1.5 deafe are also dumbe; and thus much of the lesser part of the nerue.

The thicker part of the nerue which is soft, and is properly the Nerue of hearing, because it of it selfe is the cause of this sense; is led through the hole of the foresayd passage and runneth out into the dens or caues of the stony processe: yet the larger branches doe deter∣mine * 1.6 in the first cauitie as being the largest and of most vse, where they are dilated like a membrane and make the chiefe instrument of hearing. Wherefore the receiued opinion is, that in this cauity the sense of hearing is especially administred, because into it the Ani∣mall spirit entreth through the nerue, & is there mixed with the Inbred ayre. Out of this 1. cauity through small proforations of the foresaid cauitie run certaine small threds into the other two cauities, which are communicated to the membrane wherewith they are com∣passed.

The vse of this nerue is (according to Galen in the sixth chapter of his eight booke de v∣su * 1.7 partium & Auerrhoes 2. Collect.) to be the Organ of hearing, and to receiue the sensible obiect that commeth from without, and to leade the images of the sounds vnto the braine as vnto their competent Iudge and Censor saith Laurentius.

But from a branch of the fourth coniugation of the braine, there departeth a very * 1.8 small surcle, which with a winding passage entereth into the cauity of the Eare neere the bony canale which goeth to the palate, then it cleaueth obliquely to the Tympane, and after to the Hammer aboue the insertion of the muscle, and proceeding on perforateth the stony bone in the backeside of the hole of the hearing: then, a little reflected, it creepeth * 1.9 downeward till it meete and ioyne it selfe with a smaller and harder branch of the fift con∣iugation. This Eustachius calleth a Nerue, others call it the chord or thred which, say they, runneth through the middest of the membrane of the Tympane; but whence it ariseth and whither it would, or whether it be a nerue or an artery, they freely confesse that they are ignorant.

Notes

• * 1.1

  Where it ari∣seth.
• * 1.2

  How many waies a nerue becomes hard and soft.
• * 1.3

  3 branches.
• * 1.4

  Small threds of the audi∣tory nerue.
• * 1.5

  Why those that are born deafe are also dumbe.
• * 1.6

  The very nerue of hearing.
• * 1.7

  The vse of it.
• * 1.8

  The Chord.
• * 1.9

  Eustachius.