Dr. Willis's practice of physick being the whole works of that renowned and famous physician wherein most of the diseases belonging to the body of man are treated of, with excellent methods and receipts for the cure of the same : fitted to the meanest capacity by an index for the explaining of all the hard and unusual words and terms of art derived from the Greek, Latine, or other languages for the benefit of the English reader : with forty copper plates.

CHAP. XXIII. The Description of the eighth Pair of Nerves.

THE Conjugation of the Nerves of the eighth pair, accounted by the Ancients for the sixth, is cal∣led the Wandring pair; to wit, for that its Nerve, not content with one member or region of the Body, is thought to respect divers parts, and those different, and situate at a great distance one from another, and to reach forth its branchings, not only in the neighbourhood about the Head and Neck, but through the whole cavity of the middle and lowest Belly, and to most of the Bowels in ei∣ther. But indeed this nerve hath a province large enough, yet not so diffuse as is commonly thought: for many other nerves, inoculated into this, joyn themselves with it, and are accounted a part of it, although they have distinct beginnings, and going away again from the nerve of the eighth pair, have peculiar diva∣rications, and different from it. Wherefore, that we may give to each its own, we shall endeavour to pro∣secute this nerve of the wandring pair from the beginning to the end; and also shew the confederations and coincidences or joynings together of others with it.

The eighth Conjugation therefore of the Nerves arises below the auditory or hearing nerves out of the sides of the oblong Marrow, its root consisting of numerous Fibres. In a man thereare at least twelve, some of which are greater, others smaller; to which is added a noted Fibre, or rather Nerve, much great∣er than the rest, from the spinal Marrow, which being joyned with them, and wrapped about with the same Coat, taken from the Dura Mater, goes forth together out of the Skull, as if they all grew into one Trunk: but that accessory nerve, yea and many other Fibres, do still remain distinct under that covering and afterwards departing asunder, are carried into peculiar provinces.

Because this spinal Nerve having passed the Skull, leaving its Conjugation, is carried to the muscles of the Neck and Shoulders; besides, the noted Fibre, out of the beginning of the wandring pair, is present∣ly carried into the hard process of seventh Conjugation; and two other Fibres, having presently left the company of the rest, go into the muscles of the Throat and Neck: but the rest of the Fibres, being collect∣ed together, go forward still as Companions, and instead of their other Companions which departed srom them, they presently get new in their places; to wit, sometimes the whole trunk of the intercostal nerve it self, as is seen in most four-footed Beasts, sometimes only a branch of it comes to them, as is ob∣served in Man and some other living Creatures.

In this place where the trunk or branch of the intercostal Nerve is inoculated into the trunk of the wandring pair, a noted infolding is constituted, to wit, the trunk of the nerve being there made greater, seems to be lifted up, and to grow out into a certain Tumor like to a callous or sinewy-swelled body: here, for that it is somewhat long, it is called by Fallopius the Olive body; of which sort the same Au∣thor affirms, there comes to this nerve sometimes one, sometimes two; but in truth, one is constantly found in the trunk of the wandring pair, but the other in the neighbouring intercostal.

Of these sort of infoldings in general we shall take notice, that they are made in the Nerves, as joynts in a Cane, or knots in the stem of a Tree, viz. as often as a branch goes out of the trunk, or sliding into another place, is received into the same; and whem oftentimes some shoots go away from the place, and others come to it, the infolding there becomes greater; and so the more branches and shoots do happen to come together any where, or to go out of a nerve, the greater the bulk and magnitude of the in folding is increased: but if at any time a branch seems to proceed from any nerve without constituting an infolding, in truth, being included only in the same Coat, it is not accounted so much a branch as a companion which by a passage long before, had gone together forwards, as a single nerve it self, and distinct enough nor was it at all inoculated before its departure. But the use of these same infoldings seems to be the same with the knots in the stem of a Tree, or such as the turnings aside or by-paths that lye near cross-ways; to wit, that when the animal Spirits, together with the nervous Juyce, institute divers journies, lest mutually, meeting, they should be confounded, they may be able to turn aside a little, and depart one from another till they may recover their orders and just method.

In the Dessection of the Nerves, which are distributed to the Praecordia and Viscera, the two Ganglioform infoldings, to wit, the aforesaid in the trunk of the wandring pair, and the other near growing in the intercostal nerve, are as it were two bounding stones, which being first diligenly traced, the other threads of the Anatomical task, both on this and that side, are easily handled. But that these infoldings may be found, the trunk of the Carotidick Artery is laid open on both sides between the Muscles of the Neck; then by following its tract, the aforesaid Olive bodies come into view about the insertion of the lower Mandi∣ble; out of which, both the upper beginnings and the lower branchings of either nerve, may be de∣signed or drawn. But because about this place the nerves begin to be figured otherwise in a Man than in Brutes; that the reason of the difference may be known, we will here prosecute apart and distinctly the Neurologie or Doctrine of the Nerves of either, and first we shall deliver the Hypothesis of the wandring pair, and its consederations with the intercostal and other nerves, as they are found in Man.

The Ganglioform infolding therefore being constituted upon the Trunk of the wandring pair, receives one Nerve sent into it elsewhere, and sends forth another from it self. To this is brought a shoot from the intercostal nerve different from most brute beasts, where the whole trunk of the intercostal nerve comes, and seems to be united to the wandring pair. But from the aforesaid infolding, a noted branch being sent forth, is carried towards the Larynx, which when it is divided into three shoots, the first of them is stretched out into the Sphincter of the Throat; the second being hid under the Scutiform or Shield-like Cartilage, distributes its shoots to the upper Muscles of the Larynx, and to the Muscles by which the chink of the Larnyx is shut up; and the third also entring the Shield-like Cartilage, meets the top of the returning nerve, and is united to the same. Such an inoculating of this nerve, with the returning nerve, is constantly found in man and in all other perfect Animals; the reason of which is delivered anon.

Below the aforesaid infolding of the wandring pair, its stem, near the side of the ascending Caroditick Artery, goes forward straight downwards, and in its journey imparts some small shoots to the same, which sometimes compass about the trunk of its Vessel, sometimes are inserted into its Coats. In the lower par of the Neck this trunk of the wandring pair admits a branch of the intercostal nerve from its neighbour∣ing infolding, and in the left side about that place sends forth another nerve from it self into the re∣turning nerve, which cross branch, being stretched out only in the left side, is found in man and all brute beasts: but from thence the trunk of the wandring pair descends without any noted branchings till it comes over against the first or second Rib; where another infolding being made, many shoots and nu∣merous fibres are sent forth towards the Heart and its Appendix. But this divarication of the Cardiack nerves is not after the same manner altogether in either.

For in the left side one or two noted shoots being sent forth, together with the other shoots arising from the intercostal Nerve, are inserted into the Cardiack infolding; but many fibres going out at the same place, are distributed to the Vessels hanging to the Heart, and to its little Ears and Pericardium. In the right side a noted shoot going into the greater Cardiack infolding, another into the less, and two other shoots from the middle infolding of the intercostal Trunk towards the Cardiack infolding, associate them∣selves and are united. Besides, numerous Fibres in like manner descend into the Vessels of the Heart and the Pericardium. Also the returning Nerve in this side arising higher, is turned back about the axillary Artery, when in the left side the same going away much lower than this infolding from the Trunk of the wandring pair, compasses about the descending Trunk of the Aorta, and from thence it is turned back upwards.

The returning Nerve, although it seems a branch sent forth from the Trunk of the wandring pair, being indeed a distinct and singular nerve, comes even from the beginning of wandring pair; yet for bet∣ter conducts sake it is contained under the same Coat with the rest of the Trunk of the wandring pair. In either side about the knots of reflection or turning back, it sends forth shoots and fibres which are di∣stributed into the Vessels of the Heart. The reflected Nerve in its ascent receives in the left side a branch from the middle infolding of the Intercostal, and another from the wandring pair, but either running back, distributes many shoots to the rough Artery; then its extremity meeting with the shoot, which is sent out of the Ganglioform infolding of the wandring pair, is united to it.

A little below the coming away of the returning Nerve on the left side from the Trunk of the wandring pair, another noted branch is sent forth on both sides; which being carried towards the Heart, covering its Basis in the hinder Region, meets it on both sides, and disperses in all its process branches through the whole Superficies of the Heart. As shoots go from these branches into the hinder part of the Heart, so ma∣ny branches and shoots go from the Cardiack infoldings which are divaricated into its fore-part.

But there are two infoldings from which the Nerves are distributed into the Heart, The upper and greater is between the Aorta and the Pneumonick Artery. The nerves constituting this are one or two noted branches that descend hither from either side the Trunk of the wandring pair; but chiefly many nerves form either intercostal nerve, to wit, from the midst of its infolding. From this infolding two or three noted nerves are carried under the Aorta into the left side of the Heart. But from this infolding a shoot being sent forth, making as it were an handle, compasses about the pneumonick Artery; and a branch descending from the right Trunk of the wandring pair to the exterior part of this handle, and another, which being carried from the nerve which is destinated to the hinder region of the Heart, meet together and make the lesser infolding; from which nerves are sent into the right side of the fore-part of the Heart.

We are to take notice, That in brute Animals many more and far greater Nerves are carried from the Trunk of the wandring pair into the Heart and its Appendix than in Man, to wit, in whom the chief Cardiack nerves or belonging to the Heart proceed from the intercostal pair, as is shewed below; where∣fore in Brutes, for that reason, the wandring pair affords greater supplies or subsidies to the Heart, because the intercostal nerve searcely contributes any to it. Further, through the whole tract of the wandring pair, from whence the Cardiack nerves proceed, very many small shoots, being sent forth on both sides, are in∣serted into the Oesophagus and the Glandula's implanted without the Pericardium.

From the Region of the Heart, the Trunk of the wandring pair sends forth many noted shoots on both sides, which being carried into the Lungs, are distributed, together with the blood-carrying Vesses, through their whole substance, and in their passage step by step they follow the Pipes of the Bronchia, both the Arteries and the Veins, and many shoots being sent forth on every side, they climb upon and compass about these Vessels; then the Trunk of the same wandring pair, descending on both sides, nigh the sides of the Trachea, distributes many shoots also into the Coats of the Oesophagus.

Below the Pneumonick branches, either Trunk of the wandring pair going forwards downwards nigh the sides of the Oesophagus, is divided into two branches, viz. into the exterior or more outward, and the interior or more inward. Both the inward branches inclining towards one another mutually, do again grow into the same Nerve, which being sent straight down towards the Oesophagus, and being carried nigh the inward part of its Orifice, is bent back from thence, and creeps through its upper part. From both branchs, being carried nigh the opposite parts of the superior Orifice, many shoots are produced, which being mutually inoculated, do constitute the nerves infolding like a little net. The Stomachical lower branch sends forth very many fibres and shoots nigh the left part of the bottom of the Ventricle, which are united with others, sent forth from the Mesenterick and Splenetick infolding. Further, in the right part of the same bottom of the Ventricle, shoots being sent forth from either Stomachical branch, are united with other shoots sent upwards from the Hepatick infolding; and about this place either Trunk of the Nerves of the eighth pair seems to be terminated, for that the last that may be perceived of it are some shoots sent forth from the Stomachical branches, which are inoculated or ingraffed with the little branches or fibres sent upwards from the Mesenterick infoldings.