It is a Ca.n.a.l made likewise of Four Tunicles, which receives the Arterial Blood, to carry it back to the Heart.
_What is Flesh?_
It is a Part which is form"d of Blood thicken"d by the natural Heat; and that const.i.tutes the Body of a Muscle.
_What is Fat?_
It is a soft Body made of the Unctuous and Sulphurous part of the Blood.
_What is the _Derma_ or Skin?_
It is a Net compos"d of Fibres, Veins, Arteries, Lymphatick Vessels and Nerves, which covers the whole Body to defend it from the Injuries of the Air, and to serve as a universal Emunctory: It is very thin in the Face, sticking close to the Flesh, and is pierc"d with an infinite number of imperceptible Pores, affording a Pa.s.sage to insensible Transpiration.
_What is the _Epiderma_, or Scarf-Skin?_
It is a small fine Skin, transparent and insensible, having also innumerable Pores for the discharging of Sweat, and other Humours by {10} imperceptible Transpiration: It is extended over the whole inner Skin, to dull its too exquisite Sense, by covering the Extremities of the Nerves which are there terminated. It also renders the same Skin even and smooth, and so contributes very much to Beauty.
_What is the Hair?_
The Hairs are certain hollow Filaments planted in the Glandules of the Skin, from whence their Nourishment is deriv"d. They const.i.tute the Ornament of some Parts, cover those which Modesty requires to be conceal"d, and defend others from the injury of the Weather.
_What is a Nail?_
The Nails are a Continuity of the Skin harden"d at the end of the Fingers, to strengthen and render them fit for Work.
CHAP. IV.
_Of the general Division of a Humane Body._
_How is the Humane Body divided before it is dissected, in order to Anatomical Demonstration?_
Some Anatomists distinguish it into _Similar_ and _Dissimilar_ Parts, appropriating the former Denomination to all the simple Parts of the Body taken separately, as a Bone, a Vein, a Nerve, _&c._ but they attribute the Name of Dissimilar to all those Members that are compos"d of many Similar or Simple Parts together; such are the Arms, {11} Legs, Eyes, _&c._ wherein are contain"d all at once, Bones, Veins, Nerves, and other parts.
Others divide it into _containing_ and _contained_ Parts, the former enclosing the others, as the Skull includes the Brain, and the Breast the Lungs; whereas the contained Parts are shut up within others; as the Entrails within the Belly, the Brain within the Skull, _&c._
Others again divide the whole Body into _Spermatick_ and _Sanguineous_ Parts; the former being those which are made at the time of Formation; and the latter all those that are grown afterward by the Nourishment of the Blood.
_Are there not also other Methods of dividing the Humane Body?_
Yes: Many Persons consider it as a Contexture of Bones, Flesh, Vessels and Entrails, which they explain in four several Treatises, whereof the first is call"d _Osteology_, for the Bones; the second _Myology_, for the Muscles; the third _Angiology_, for the Veins, Arteries and Nerves, which are the Vessels; and the fourth _Splanchnology_, for the Entrails.
But lastly, the most clear and perspicuous of all the Divisions of the Body of Man, is that which compares it to a Tree, whereof the Trunk is the Body, and the Branches are the Arms and Legs. The Body is divided into three _Venters_, or great Cavities, _viz._ the Upper, the Middle, and the Lower, which are the Head, the Breast, and the lower Belly. The Arms are distributed into the Arms properly so called, the Elbow and Hands; and the Legs in like manner into Thighs, Shanks, {12} and Feet: The Hands being also subdivided into the _Carpus_ or Wrist, _Metacarpium_ or Back of the Hand, and the Fingers; as the Feet into the _Tarsus_, _Metatarsus_, and Toes. This vision is at present follow"d in the Anatomical Schools.
CHAP. V.
_Of the Skeleton._
_Why is Anatomy usually begun with the Demonstration of the Skeleton, or Contexture of Bones?_
Because the Bones serve for the Foundation Connexion, and Support of all other Parts of the Body.
_What is the Skeleton?_
It is a gathering together, or Conjunction of all the Bones of the Body almost in their Natural Situation.
_From whence are the princ.i.p.al differences of the Bones derived?_
They are taken from their Substance, Figure, Articulation, and Use.
_How is all this to be understood?_
First then, with respect to their Substance, there are some Bones harder than others; as those of the Legs compared with those of the Back-Bone.
Again, in regard of their Figure, some are long, as those of the Arm; and others short, as those of the _Metacarpium_. Some are also broad, as those of the Skull and {13} _Omoplatae_ or Shoulder-Blades; and others narrow, as the Ribbs. But with respect to their Articulation, some are joined by thick Heads, which are received into large Cavities, as the Huckle-Bones with those of the Hips; and others are united by the means of a simple Line, as the Chin-Bones. Lastly, with relation to their Use; some serve to support and carry the whole Body, as the Leg-Bones, and others are appointed to grind the Meat, as the Teeth; or else to form some Cavity, as the Skull-Bone, and those of the Ribs.
_What are the Parts to be distinguished in the Bones?_
They are the Body, the Ends, the Heads, the Neck, the _Apophyses_, the _Epiphyses_, the _Condyli_ or Productions, the Cavities, the _Supercilia_ or Lips, and the Ridges.
The Body is the greatest Part, and the middle of the Bone; the Ends are the two Extremities; the Heads are the great Protuberances at the Extremities; the Neck is that Part which lies immediately under the Head; the _Apophyses_ or Processes are certain Bunches or k.n.o.bs at the Ends of the Bones, which const.i.tute a Part of them; the _Epiphyses_ are Bones added to the Extremities of other Bones; the _Condyli_ or Productions are the small Elevations or Extuberances of the Bones; the Cavities are certain Holes or hollow places; the _Supercilia_ or Lips are the Extremities of the Sides of a Cavity, which is at the End of a Bone; the Ridges are the prominent and saliant Parts in the length of the Body of the Bone. {14}
_How are the Bones join"d together?_
Two several ways, _viz._ by _Articulation_ and _Symphysis_.
_How many sorts of Articulations are there in the Bones?_
There are generally two kinds, _viz._ _Diarthrosis_ and _Synarthrosis_.
_What is Diarthrosis?_
_Diarthrosis_ is a kind of Articulation which serves for sensible Motions.
_How many kinds of Diarthroses, or great Motions are there?_
There are Three, _viz._ _Enarthrosis_, _Arthrodia_, and _Ginglymus_.
_Enarthrosis_ is a kind of Articulation which unites two Bones with a great Head on one side, and a large Cavity on the other; as the Head of the Thigh-Bone in the Cavity of the _Ischion_ or Huckle-Bone.
_Arthrodia_ is a sort of Articulation, by the means whereof two Bones are join"d together with a flat Head receiv"d into a Cavity of a small depth.
Such is the Head of the Shoulder-Bone with the Cavity of the _Omoplata_ or Shoulder-Blade; and that of the Twelfth _Vertebra_ of the Back with the first of the Loins.
_Ginglymus_ is a kind of Articulation which unites two Bones, each whereof hath at their Ends a Head and a Cavity, whereby they both receive and are received at the same time, such is the Articulation in the Bones of the Elbow and the _Vertebrae_.