Page:Cyclopaedia, Chambers - Volume 2.djvu/955

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Thus, S T, (Tab. Trigonometry, Fig.?*) ^ the Verfed Sine of the Arch RTj and A S the Verfed Sine of the Arch A R, the Complement of the former. See Sine.

VERSIFICATION, the Art, or Manner of making Verfe • alfo the Tune and Cadence of Verfe. See Verse.

Verfification, is properly applied to what the Poet does more by Labour, Art, and Rule, than by Invention, and the Genius or Furor Toeticzis.

The Matter of Verification is long and fhort Syllables, and Feet compos'd of them ; and its Form, the Arrangment of them in correct, numerous, and harmonious Verfes ; But this is no more than a mere Tranflator may pretend to, and which the Catilimrian War, put in Verfe, might not merit.

'Tis with Reafon, therefore, that thefe fimple Matters are diftinguifh'd from the grand Poetry, and call'd by the Name Versification. See Poetry.

In erreft, there is much the fame difference between Grammar and Rhetorick, as between the Art of making of Verfes, and that of inventing Poems.

VERSION, a Tranjlation of fome Book, or Writing, out of one Language into another. See Translation.

VERT, in Heraldry, the Term for a green Colour. See Green, and Colour.

It is called Vert in the blazon of the Coats of all under the Degree of Nobles 5, but in Coats of Nobles, 'tis call'd Emerauld 5 and in thofe of Kings, Venus.

In engraving, 'tis exprefs'd by Diagonals, or Lines drawn athwart, beginning at the finifter Corner of the Efcutcheon ; as in the Figure adjoining.

In lieu of Vert, the French Heralds ufe Simple, or Syno- ple. See Sinople.

Vert, or green Hue, in Foreft Law, any thing that grows, and bears a green Leaf within the Foreft, that may cover a Deer. See Forest, Game, &c.

It is either Over-Vert, or Nether-Vert 5 Over-Vert is the great Woods, which in Law- Books are ufually called Hault- Sois.

Nether-Fir? is the Under- Woods, otherwife call'd Silb- Sois.

We fometimes alfo meet with Special Vert, which denotes all Trees growing in the King's Wood, within the Forefl: 3 and thofe that grow in other Men's Woods, if they are fuch Trees as bear Fruit to feed the Deer.

VERTEBRALES, in Anatomy, a Pair of Mufcles, fer- ving to ftretch out all the Vertebra of the Back. See Ver-

TEBRJE,

VERTEBRAE, a Chain of little Bones, reaching from the Top of the Neck, down the Back, to the Os Sacrum ; and forming a third Part of the human Skeleton, call'd the Spina Dorfi. See Spina.

The Vertebra have their Name a vertendo 5 becaufe 'tis on them the Head and Trunk turn : The Greeks call them Sporidyli, for the fame Reafon.

The Vertebra are 24-in Number ; Seven of 'cm belong to the Neck, twelve to the Back, and five to the Loins. See Neck, Loins, &c.

They lie not in a {trait Line j thofe of the Neck bend in- wards, and thofe of the Back outwards, for enlarging the Cavity of the Thorax 5 and thofe, again, of the Loins bend inwards, and thofe of the Os Sacrum outwards, to enlarge the Cavity of the Bafon.

The Body of each Vertebra is fpongious and cavernous 5 having in the middle a large Perforation, thro' which the Medulla Spinalis partes, and feven Apophyfes, or ProcefTes. The Fore-part of this Body is round and convex 3 the Hind-part fomewhat concave : its upper and lower Sides-are plain ; each cover'd with a Cartilage which is pretty thick forwards, but thin backwards, by means whereof it is, that we bend the Body forwards ; the Cartilages yielding to the Preffure of the Bodies of the Vertebra, which in that Mo- tion come clofer to one another : Which could not be effec- ted, if the harder Bodies of the Vertebra were clofe to one another.

The ProcefTes of each Vertebra are of three forts : Two tranfverfe, or lateral • in each of which there is a Tendon of the Vertebral Mufcles inferred : Four oblique ones ; by which the Vertebra are articulated to one another : and one acute, on the hindmoft Part of the Vertebra.

Thefe ProcefTes, which are peculiarly call'd the Spines, form, with the hinder or concave Part of the Body of the Vertebra, a large Hole in each Vertebra ; and all the Holes anfwering one another make a Channel for the Defcent of the Spinal Marrow, which fends out its Nerves to the feve- ral Parts of the Body by Pairs, thro' two fmall Holes, form'd by the jointing of four Notches in the Sides of each fuperior and inferior Vertebra. \ See Medulla Spinalis.

The Vertebra are articulated to one another by Gingly- mus : For the two defcending oblique ProcefTes of each fu- perior Vertebra of the Neck and Back, have a little dimple in their Extremities, wherein they receive the Extremities of the two afcending oblique ProcefTes of the inferior Verte-

bra • fo that the two afcending ProcefTes of each Vertebra of the Neck and Back are received, and the two defcend- ing do receive, except the firft of the Neck, and laft of the Back ; but the afcending ProcefTes of each Vertebra of the Loins receive, and the two defcending are received 5 contra- ry to thofe of the Neck and Back.

The Vertebrce are all tied together by a hard Membrane, made of ftrong and large Fibres : It covers the Body of all the Vertebrce forwards ; reaching from the firft of the Neck to the Os Sacrum. — There is another Membrane, which lines the Canal, made by the large Hole of each Vertebra ; which alfo ties them all together : betides* the Bodies of each Vertebra are tied to one another by the intervening Cartilages 5 and the Tendons of the Mufcles, which are in- ferted in their ProcefTes, tic them together behind.

This Structure of the Spine is admirable ; for had it been all one Bone, we could have had no Motion in our Backs 5 had it been of two or three Bones articulated for Motion, the Medulla Spinalis muft have been neceflarily bruis'd at every Angle, or Joint : befides, the whole would not have been fo pliable for the feveral Poftures we have occafion to put our felves in : If it had been made of feveral Bones, without intervening Cartilages, we fhould have had no more ufe of it, than if it had been but one Bone. If each Ver- tebra had had its own diftin£t Cartilages, it might have been

eafily diflocated. -Laftly, the oblique ProcefTes of each

fuperior and inferior Vertebra, keep the middle one, that it can neither be thruft backwards norfbrwards, foasto comprefs the Medulla Spinalis.

The Vertebra of the Neck differ from the reft, in that they are fmaller and harder, their tranfverfe ProcefTes per- forated for the PafTages of the Vertebral VelTels, and their acute ProcefTes forked and ftrait : Add, that the firft and fe- cond have fomething peculiar to themfelves. The firft, cal- led Atlas, is ty'd to the Head; and moves with it upon the fecond, femicircularly. See Atlas.

The fecond is called Epifirophaus, or Vertebra fyentata : In the middle, between its two oblique afcending ProcefTes, it has a long and round Procefs like a Tooth, which is re- ceiv'd into a Sinus of the Atlas 5 and upon it, the Head, with the firft Vertebra, turns half round, as upon an Axis. The Extremity of this Procefs is knit to the Occiput, by a fmail but ftrong Ligament. A Luxation of this Tooth is mortal, becaufe it compreftes the Medulla Spinalis.

The third is call'd Axis : The reft have no particular Names.

The Vertebrce of the Back differ from the reft in this, that they are larger than chofe of the Neck, and fmaller than thofe of the Loins : Their acute ProcefTes flope downwards upon one another. They have in each fide ot their Bodies a fmall Dimple, wherein they receive the round Extremi- ties of the Ribs : The uppermoft of 'em is fometimes cali'd the Crejl ; the fecond the Axillaris •■> and the reft Cq/lalcs.

The Vertebra of the Loins are the broadeft 3 and the laft of them, the largeft of all the Vertebrce.

Tho each Vertebra has but a fmall Motion, yet the Mo- tion of 'em all is confiderable : The Head, we have oblerv- ed, moves only backwards and forwards on the firft Vertebra, and femicircularly on the fecond.

The Motion of the other Vertebra of the Neck is not lb manifeft, yet it is greater than that of the Vertebra of the Back 5 becaufe their acute ProcefTes are fhort and ftrait, and the Cartilages which are between their Bodies, thicker. The Vertebra of the Back have the leaft Motion of any 5 becaufe their Cartilages are thin, their acute ProcefTes long, and very near to one another : And they are fixed to the Ribs, which neither move forwards nor backwards. The greateft Motion of the Back, is perform'd by the Vertebra of the Loins 5 becaufe their Cartilages are thicker, and their acute ProcefTes are at a greater diftance from one another : For the thicker the Cartilages are, the more we may bend the Body forwards 5 and the greater diftance there is be- tween the acute ProcefTes, the more we may bend backwards.

Such is the Structure and Motion of the Vertebra, when in their natural Pofition : but we frequently find 'em vari- oufty diftorted. If the Vertebra of the Back ftick out, ic conftitutes what we call a SuucFd Sack: And in fuch Cafes the Cartilages between the Vertebra are very thin and hard, forwards, butconfiderably thick backwards where the oblique ProcefTes of the fuperior and inferior Vertebra are at a con- fiderable diftance from one another, which diftance is fill'd up with a vifcous Subftance.

This Inequality of the thicknefs of the Cartilages hagoeos, either by a Relaxation, or a Weaknefs of the Ligaments arid Mufcles faften'd to the backfide of the Vertebra : in which Cafes, their Antagonifts finding no oppofition, remain in a continual Contraction.

The Os Sacrum does alfo conflft of Vertebra in Children 5 which grow fo clofe together in Adults, that they make but one large and folid Bone, of the Figure of an lfofceles Tri- angle, whofe Bafis is ty'd to the laft Vertebra of the Loins, and the upper Part of its Sides to the Ilia, and its Point to the Os Coccygis. See Sacrum Os.

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