The Compleat Surgeon Part 9

_Of the Anatomy of the Nerves, Arteries, and Veins in general._

_What is the Structure of the Nerves?_

The Nerves are round white Bodies enclos'd in a double Membrane, communicated to them from the two _Meninges_ of the Brain: Their Office is to convey the Animal Spirits into all the Parts.

_Where is the Root and first beginning of all the Nerves?_

All the Nerves take their Original from the _Medulla Oblongata_, and that of the Spine.

_How is the distribution of them made thro' the whole Body?_

It is directly perform'd by Conjugations or Pairs, whereof one goes to the Right-hand, and the other to the Left: There are nine Pairs of them that proceed from the _Medulla Oblongata_ and enter into the Skull; and a Tenth that comes from the Marrow which lies between the Occipital and the first _Vertebra_ of the Neck. It {59} pa.s.seth thro' the Hole of the _Dura Mater_, thro' which the Vertebral Artery enters, to distribute its Branches into several Parts.

_To what Use are the nine Pairs of Nerves appropriated, which proceed from the Root of the Brain?_

They are chiefly design'd for the Senses, and also for the Motion of their Organs, of which the Ancients discover'd only seven.

The first Pair of Nerves is call'd the _Olfactory_, and serves for the Smelling.

The second Pair is the _Optici_ or _Visorii Nervi_, and bestows upon the Eyes the Faculty of seeing.

The third is term'd _Motorii Oculorum_, being serviceable for the Motion of the Eyes.

The fourth Pair is nam'd _Oculorum Pathetici_, which shews the Pa.s.sion of the Mind in the Eyes, whereto it imparts a String as well as to the Lips.

The fifth is call'd the _Gustative_, and appropriated to the Taste, because it sends Twigs more especially to the Tongue, as also to the Fore-head, Temples, Face, Nostrils, Teeth, and Privy-Parts.

The Sixth is likewise for the Taste, and goes to the Palate.

The seventh is the _Auditive_ Nerve, that enters into the _Os Petrosum_, where it divides it self into many Branches, which when gone forth, are distributed to the Muscles of the Tongue, Lips, Mouth, Face, Fore-head, Eye-Lids, &c.

The eighth is the _Os Vagum_, or wandering Pair, which is united to the Intercostal Nerve, as also to the Recurrent, Diaphragmatick, Mesenterick, &c. {60}

The ninth Pair, after having form'd a Trunk with the eighth, disperseth its Twigs several ways, whereof one is join'd with the Twig to the tenth, to be distributed together into the Muscle _Sternohyoideus_, and into the Tongue.

The _Intercostal_ and _Spinal_ are not Pairs of Nerves, but only Branches or Twigs of other Pairs.

_What is the Distribution and Use of the thirty Pairs of Nerves that proceed from the Spinal Marrow?_

There are seven that go forth from the several _Vertebra's_ of the Neck, twelve from those of the Back, five from the Loins, and six from the _Os Sacrum_, according to the following Progression.

The first of the seven Pairs of Nerves of the Neck proceeds from between the Occipital Bone and the first _Vertebra_, nam'd _Atlas_, its Fibres being lost in the Muscles of the hinder-part of the Head and Neck.

The second Pair springs from between the first and second _Vertebra_ of the Neck; the Fibres whereof are lost in the Muscles of the Head, and in the Skin of the Face.

The third Pair issueth from between the second and third _Vertebra_ of the Neck; and its Fibres are lost in the Flexor Muscles and Extensors of the Neck.

The fourth, fifth, sixth, and seventh Pairs proceed from between the _Vertebra's_, as before, but their Fibres are lost in the Neck of the _Omoplata_, in the Arm, and in the _Diaphragme_ or Midriff. Here it ought to be observ'd by the way that the Arms receive Branches not only from the {61} four last Pairs of the Nerves of the Neck, but also from the two first Pairs of the Back, which are extended even to the end of the Fingers: Whence it happens that in the Palsie of the Arms, Remedies are usually apply'd to the _Vertebra's_ of the Neck; and that in Phlebotomy or letting Blood, care must be taken to avoid p.r.i.c.king the Nerve, which accompanies the Basilick Vein in the Elbow.

The twelve Pairs of Nerves that have their Beginning from between the _Vertebra's_ of the Back, are each of them divided into two Branches, as the others; and their Branches are distributed in like manner to the Muscles of the Breast, and to those of the Back and _Abdomen_.

The five Pairs which take their Rise from between the _Vertebra's_ of the Loins, have thicker Branches than the others, and the distribution of them is made to the Muscles of the Loins, _Hypogastrium_, and Thighs.

Of the six Pairs of Nerves that proceed from the _Os Sacrum_, the four Upper with the three Lower of the Loins, send forth Fibres of Nerves to the Thigh, Leg, and Foot; and the two last Pairs impart Nerves to the _a.n.u.s_, Bladder, and privy Parts.

_What is the Structure of the Arteries?_

The Arteries are long and round Ca.n.a.ls, consisting of four sorts of Tunicks or Membranes, which have their Rise from the left Ventricle of the Heart, from whence they receive the Blood, and convey it to all the Parts of the Body for their Nourishment.

_What is the Construction of these four Tunicks or Membranes of the Arteries?_ {62}

The first being thin and Nervous in its outward Superficies, is in the Inside a _Plexus_ or Interlacement of small Veins and Arteries, and Fibres of Nerves, which enter into the other following Tunicks, to nourish them.

The second sticking close to the former, is altogether full of whitish Glandules, that serve to separate the serous Particles of the Blood.

The third is intirely Musculous, and interwoven with Annular Fibres.

The fourth is very thin, and hath its Fibres all streight.

_Whence proceeds the Pulse or beating of the Arteries?_

It is deriv'd from the Heart, and exactly answers to its Motion of _Diastole_ and _Systole_.

_By what Name is the first Trunk of the Arteries call'd, and what is the Effect of the Distribution made thence to the whole Body?_

The first Trunk of the Arteries is nam'd _Aorta_, or the _thick Artery_, which proceeds immediately from the left Ventricle of the Heart, whereto it communicates before its departure from the _Pericardium_, one or two small Branches call'd the _Coronary_: Afterward it is divided into two Branches, whereof one goes upward, and is term'd the _Ascending Artery_; and the other downward, under the Denomination of the _Descending Artery_.

The _Ascending Artery_ ariseth upward along the _Aspera Arteria_ or Wind-Pipe, to the Clavicles, and is there divided into two Branches, call'd the _Subclavian Arteries_, one whereof goes forward to the Right side, and the other to the Left; and they both send forth on each side {63} divers Branches, which take their Names from the several Parts, whereto they are distributed; such are the _Carotides_ or _Soporales Interni & Externi_, which pa.s.s to the Head; the _Mediastina_; the _Intercostal_; the _Axillar_, and others.

The _Descending Artery_, before its departure from the Breast, affords certain Branches to the _Pericardium_, Diaphragm, and lower Ribs; afterward it penetrates the Diaphragm, and const.i.tutes seven double Branches. The first is of those that are call'd _Coeliack_, and which go to the Liver and Spleen. The second Branch contains the _Upper Mesenterick_. The third the _Emulgent_, which pa.s.s to the Reins. The fourth the _Spermatick_, which are extended to the Genitals. The fifth the _Lower Mesenterick_. The sixth the _Lumbar_. And the seventh the _Muscular_. But a.s.soon as the great Trunk is come downward to the _Os Sacrum_, it divides it self into two thick Arteries nam'd the _Iliack_, which are distributed on both sides, each of them making two Internal and External Branches, which likewise impart Sprigs or lesser Arteries, to the Bladder, _a.n.u.s_, _Matrix_, and other adjacent Parts: Then the Master-Branch forms the _Crural_ Arteries on the inside of the Thighs, which are communicated by multiplying their Number even to the ends of the Toes, in pa.s.sing over the External Ancle-Bones of the Feet.

_What is the Structure of the Veins?_

The Veins are long and round Ca.n.a.ls made of four kinds of Tunicks or Membranes, whose Office it is to receive the Blood that remains after the Nourishment is taken, and to carry it back to the Heart to be reviv'd. {64}

_What is the Form of the four Tunicks that make the Ca.n.a.ls of the Veins?_

The first is a Contexture of Nervous and streight Fibres. The second is a _Plexus_ of small Vessels that carry the Nourishment. The third is all over beset with Glandules thro' which are filtrated the serous Particles of the Blood contain'd in the Vessels of the second Tunicle. The fourth is a Series of Annular and Musculous or Fleshy Fibres.

_Which are the most numerous, the Arteries or the Veins?_

The Number of the Veins exceeds that of the Arteries; and there are scarce any Arteries without Veins accompanying them.

_Where is the Beginning and Original of all the Veins?_

All the Veins have their Root in the Liver, and two of the three great Trunks that proceed from thence, are call'd _Vena Portae_, and _Vena Cava_; and the third is twofold, _viz._ the _ascending_ and the _descending_.

The _Vena Portae_ is distributed to all the Parts contain'd in the lower Belly, and terminated in the Fundament; where it makes the Internal Haemorrhoidal Veins.