The _Vena Cava_ is immediately divided into two thick Branches, one whereof ariseth upward to the Right Ventricle of the Heart, and forms the _ascending Vena Cava_; as the other goes downward to the Feet, and const.i.tutes the _descending_.
_What is the Distribution of the ascending _Vena Cava_?_
It perforates the Diaphragm, goes to the Heart, and ascends from thence to the Clavicles, {65} after having communicated to the Midriff in pa.s.sing, a small Branch call"d the _Phrenicus_; as also one or two to the Heart, nam"d the _Coronary_; and some others to the upper Ribs, besides the single Branch, term"d _Azygos_, only on the right side. But the Trunk of the _ascending Vena Cava_, being once come up to the Clavicles, is divided into two Branches, well known by the Name of the _Subclavian_, one whereof Shoots forth toward the Right side, and the other toward the Left; and they both make various Ramifications like to those of the thick ascending Artery, by producing the _Cervicalis_ or _Soporalis_, and the Internal and External _Jugulars_ that go to the Head; as also the _Axillars_, which pa.s.s to the Arms and Shoulders, forming the _Cephalick_, the _Median_, and the _Basilick_ on the inside of the Elbow.
The _descending Vena Cava_ in like manner accompanieth the Ramifications of the _Aorta_, or thick descending Artery, to the fourth _Vertebra_ of the Loins, where it sends forth two Branches, nam"d the _Iliack_, one whereof goes to the Right side, and the other to the Left, both inwardly and outwardly; imparting divers Twigs or lesser Branches to all the Parts contain"d in the _Abdomen_ or lower Belly, even as far as the Fundament, where it makes the External _Haemorrhoidal_ Veins. Afterward the outward Branch of the _Iliack_ descends in the Thigh, to form the _Crural_, and others, as far as the _Saphaena_, together with those that are situated at the end of the Feet.
{66}
CHAP XII.
_Of the Anatomy of the _Abdomen_, or lower Belly_.
_What is the clearest Division of the Human Body into various Parts, and that which is most followed in the Anatomical Schools?_
It is that which const.i.tutes three _Venters_, that is to say, the Upper, the Middle, and the Lower, which are the Head, the _Thorax_ or Breast and the _Abdomen_ or lower Belly, together with the Extremities, which are the Arms and Legs.
_What is the lower Belly?_
It is a Cavity of the Body that contains the nourishing parts, as the Reins, the Bladder, and all those that are appropriated to Generation in both s.e.xes.
_What is to be consider"d outwardly in the lower Belly?_
Its different Regions, and the several parts therein contain"d.
_What are these Regions?_
They are the _Epigastrick_, the _Umbilical_, and the _Hypogastrick_.
_What is their Extent?_
It is from the _Xyphoides_ or Sword-like Cartilage to the _Os Pubis_, the division whereof into three equal Parts, const.i.tutes the three different Regions; the _Epigastrium_ being the first upward, the _Umbilicus_ the second, and the _Hypogastrium_ the third. {67}
_What Are the Parts contain"d in the _Epigastrium_, and what Place do they possess therein?_
The Parts contain"d in the _Epigastrium_ are the Liver, the Spleen, the Stomach, and the _Pancreas_ or Sweet-bread, which lies underneath: The Stomach takes up the middle before, the Liver being plac"d on the Right side, and the Spleen on the Left; so that these two sides of the Epigastrick Region, are call"d the Right and Left _Hypochondria_.
_What Parts are there contain"d in the Umbilical Region, and what is their situation?_
They are the most part of the thin Intestines or small Guts, _viz._ the _Duodenum_, the _Jejunum_, and the _Ileon_, which have their Residence in the middle, where they are encircled with a Portion of the two great Guts, _Caec.u.m_ and _Colon_, that take possession of the Sides, otherwise call"d the Flanks. The Reins or Kidneys are also in this Place, above, and somewhat backward.
_What Parts are there contain"d in the _Hypogastrium_, and of what Place are they possest?_
The greater part of the thick-Guts, _Coec.u.m_, and _Colon_, are enclos"d therein, with the entire _r.e.c.t.u.m_; there is also a Portion of the _Ileon_, which hides it self in the sides of the _Ilia_, or Hip-Bones: In the middle under the _Os Pubis_, the Bladder is situated on the Gut _r.e.c.t.u.m_ in Men, and the _Matrix_ in Women lies between the _r.e.c.t.u.m_ and Bladder.
_After what manner is the opening of a Corps or dead Body perform"d at a publick Dissection?_ {68}
It is begun with a Crucial Incision in the Skin from underneath the Throat downward, traversing from one side to another in the Umbilical Region; then this Skin is pull"d off at the four Corners, and the _Panicula Adiposa_ is immediately discover"d: Under this Fat lies a Fleshy Membrane, call"d _Membrana Carnosa_; and after that, the common Membrane of all the Muscles of the lower Belly. Thus we have taken a View of what Anatomists commonly term the _five Teguments_, that is to say, the _Epiderma_ or Scarf-Skin, the _Derma_ or true Skin, the _Panicula Adiposa_, the _Panicula Carnosa_ or _Membra.n.u.s Carnosa_, and the common Membrane of the Muscles.
The five Teguments being remov"d, we meet with as many Muscles on each side, _viz._ the descending Oblique, the ascending Oblique, the Transverse, the streight, and the Pyramidal, by the means whereof the Belly is extended and contracted. Afterwards appears a Membrane nam"d _Peritonaeum_, which contains all the Bowels, and covers the whole lower Belly, being strongly fasten"d to the first and third _Vertebra"s_ of the Back. The Fat skinny Net which lies immediately under the _Peritonaeum_, is call"d _Epiploon_ and _Omentum_, or the Caul; it floats over the Bowels, keeping them in a continual Suppleness necessary for their Functions, maintains the Heat of the Stomach, and contributes to Digestion.
It remains to take an Account of the Bowels _viz._ the Stomach, Mesentery, Liver, Spleen, Kidneys, Bladder, and Guts, together with the Parts appointed for Generation, which in Men {69} are the Spermatick Vessels, the t.e.s.t.i.c.l.es, and the _p.e.n.i.s_; and in Women, the Spermatick Vessels, the t.e.s.t.i.c.l.es or Ovaries, the _Matrix_, and its _v.a.g.i.n.a_ or Neck.
_What is the Stomach?_
It is the Receptacle of the Aliments or Food convey"d thither thro" the _Oesophagus_ or Gullet, which is a Ca.n.a.l, or kind of streight Gut that reacheth from the Throat to the Mouth of the Stomach. The Stomach it self is situated immediately under the _Diaphragm_ or Midriff, between the Liver and the Spleen, having two Orifices, whereof the Left is properly call"d _Stomachus_, or the Upper, and the Right (at its other Extremity) _Pylorus_, or the lower Orifice. Its Figure resembleth that of a Bag-Pipe, and the greater part of its Body lies toward the Left side. It is compos"d of three Membranes, _viz._ one Common, which it receives from the _Peritonaeum_; and two Proper; the two uppermost being smooth, and the innermost altogether wrinkled.
_What is the _Pancreas_ or Sweet-bread?_
It is a Fat Body, consisting of many Glandules wrapt up in the same Tunicle, being situated under the _Pylorus_ or lower Orifice of the Stomach: It helps Digestion, and hath divers other uses; but its princ.i.p.al Office is to separate the serous Particles of the Blood, to be convey"d afterward into the Gut _Duodenum_, by a Ca.n.a.l or Pa.s.sage, nam"d the _Pancreatick_. This Juice serves to cause the Chyle to ferment with the Choler, in order to remove the grosser Particles from those that ought to enter into the Lacteal Vessels.
_Into how many sorts are the Guts distinguish"d?_ {70}
There are two sorts, _viz._ the thin and the thick.
_How many thin or small Guts are there?_
Three; that is to say, the _Duodenum_, the _Jejunum_, and the _Ileon_.
_How many thick Guts are there?_
Three likewise; _viz._ the _Coec.u.m_, the _Colon_, and the _r.e.c.t.u.m_.
_Why are some of them call"d thin Guts, and others thick?_
Because the thin are smaller, being appointed only to transport the Chyle out of the Stomach into the Reserver; whereas the thick are more large and stronger, serving to carry forth the gross Excrements out of the Belly.
_Are the six Guts of an equal length?_
No, the _Duodenum_, which is the first of the thin Guts, is only twelve Fingers breadth long. The _Jejunum_, being the second, so call"d because always empty, is five Foot long: The third is nam"d _Ileon_, by reason of its great Turnings which oblige it to pa.s.s to the _Os Ilion_, where it produceth a Rupture; it extends it self almost twenty Foot in length.
The first of the thick Guts, known by the Name of _Coec.u.m_, is very short, and properly only an _Appendix_ or Bag of a Finger"s length. That which follows is the _Colon_, being the largest of all, and full of little Cells, which are fill"d sometimes with Wind and other Matters that excite the Pains of the Colick. It encompa.s.seth the thin Guts, in pa.s.sing from the top to the bottom of the Belly, by the means of its great Circ.u.mvolutions, and is from eight to nine Foot long. The last is the _r.e.c.t.u.m_ or {71} streight Gut, so nam"d, because it goes directly to the Fundament: It is no longer than ones Hand, but it is fleshy, and situated upon the _Os Sacrum_, and the _Coccyx_ or Rump-Bone.
_What is the _Peristaltick_ Motion of the Guts?_
It is the successive Motion and Undulation, whereby the Guts insensibly push forward from the top to the bottom, the Matters contain"d in them; and that Motion which on the contrary is perform"d from the bottom to the top, is term"d the _Antiperistaltick_ as it happens in the _Iliack_ Pa.s.sion, or twisting of the Guts, call"d _Domine Miserere_, by reason of its intolerable Pain.
_What is the Mesentery?_
It is a kind of Membrane somewhat fleshy, which is join"d to the Spine in the bottom and middle of the Belly, and by its folding, keeps all the Guts steady in their place; it is all over beset with red, white, and Lymphatick Vessels; that is to say, those that carry the Blood, Chyle, and _Lympha_, which serves to cause this last to run more freely, and to ferment. Three notable Glandules are also observ"d therein, the greatest whereof lies in the middle, and is nam"d _Asellius"s Pancreas_; the two other lesser are call"d _Lumbar_ Glandules, as being situated near the Left Kidney. From each of these Glandules proceeds a small Branch; and both are united together to make the great _Lacteal_ Vein, or _Thoracick_ Ca.n.a.l. This Tube conveys the Chyle along the _Vertebra"s_ of the Back to the Left _Subclavian_ Vein; from whence it pa.s.seth into the ascending _Vena Cava_, and descends in the Right Ventricle of the Heart, {72} where it a.s.sumes the form of Blood; from whence it pa.s.seth to the Lungs thro" the _Pulmonary_ Artery; then it returns to the Heart thro" the _Pulmonary_ Vein, and goes forth again thro" the Left Ventricle of the Heart, between the _Aorta_ or great Artery, to be afterward distributed to all the Parts of the Body.
This is the ordinary Pa.s.sage for the Circulation of the Chyle, and the Sanguification of the Heart.
_What is the Liver?_
The Liver, being the thickest of all the Bowels, is plac"d in the Right _Hypochondrium_, at the distance only of a Fingers breadth from the Diaphragm; its Figure much resembling that of a thick piece of Beef: It is Convex on the outside, and Concave within; its Substance is soft and tender, its Colour and Consistence being like coagulated Blood: It is cleft at bottom, and divided into two Lobes, _viz._ one greater, and the other less: Its Office is to purifie the Ma.s.s of Blood by Filtration; and it is bound by two strong Ligaments, the first whereof adheres to the Diaphragm, and the second to the _Xiphoides_ or Sword-like Cartilage. Two great Veins take their Rise from hence, _viz._ the _Vena Portae_, and the _Vena Cava_, which form innumerable Branches, as it were Roots in the Body of the Liver.
The Gall-Bladder is fasten"d to the hollow part thereof, and dischargeth its Choler into the Gut _Duodenum_, thro" the Vessels that bear the Name of _Meatus Choledochi_, or _Ductus Biliares._ This Choler is not a meer Excrement, but on the contrary of singular Use in causing the Fermentation of the Chyle, and bringing it to perfection. {73}