Page:Cyclopaedia, Chambers - Volume 2.djvu/250

 MUS

It has been already obfervcd, that the Tendon of a "Mufch confifis of the fame N umber of Fibres with the Mufch itfelf 5 with this difference, that the Cavity of the mufcular Fibres diminishing, and lofing of their former Diameter, form one tompaft, hard, tough, dry, narrow Body, which is but litrie Vafcukr : From what has been faid then, it appears, that the Rednefs of a Mufch is owing to the blood ; and its Bulk to the Fulnefs of the Arteries, Veins, oily Cells, and Lymphatics. Hence we fee, why in old Age, Leannefs, Confumptions, Atrophies, conitant Keat, and hard La- bour, their Rednefs as well as Bulk are fo diminished 5 and yet in old Age, Leannefs, &c. the Motion remains. This may be directed, when the Unfiles have no Rednefs left ; as appearsin InfecTs, whofe Flefh is not perceivable. The Fibres, Fafciculi, Arteries, and Nerves may be feparated from each other in a live or a dead Body, without breaking. They are always in a degree of Tenfion, and endued with a contractive Force; fo that when cut afunder, the Ends fly back from each other; and then they become /hotter, their Bulk is lefTen'd, and they contract themfelves into a wavy undulating kind of Surface, and throw off their proper Juices. Hence it appears they are always in a ftate of Violence, are ever oppofing their Elongation, ever endeavou- ring to ihorten themfelves, but more in a live Body than a dead one 5 and therefore require Antagonists. %. If the Cerebrum be Wrongly comprefs'd, or have any violent Contufion ; if it be fuppuratcd, obstructed, or torn, the voluntary Action of all the Mufchs immediately ceafes, as well as all Senfe and Memory; however the fpontaneous Action of the Mufchs in the Heart, Lungs, the Vifcera, and Vital Farts, remains. 3. Thefe fame Alterations being made in the Cerebellum, the Action of the Flearr, Lungs, and Life itfelf, ceafes; when yet the Vermi- cular Motion continues a long time after in the Ventricle and Interlines. 4. The Nerve of any Mufch', being com- prefs'd, tied up, corrupted, or cur, all the Motion of that Mufch, both Vital and Voluntary, immediately ceafes ; and if a nervous Trunk fending Branches to feveral Mufchs, be thus bound up, cut, &c they are all affected in the fame manner. 5. The fame things being done in any part of the fpinal Marrow, the Action of all the Mufchs whofe Nerves arife from the part affected, isdeilroy'd : And, 6. The fame things being done to the Artery which carries Blood to one or more Mufchs y the Effect is the fame. 7. The Tendon of a Mt'fch in Action does not undergo any fenfible Alteration, but the Belly fliortens, becomes hard, pale, fwoln, protuberant ; the Tendons are approached nearer, and the more moveable part faften'd to the Ten- don, is drawn towards the other lefs moveable ; which Action ofa JWl/c/e is call'd its Cojitra&io7i > which is much greater and Wronger than that inherent Contraction obfer- ved under the firlt Phenomenon ; and therefore is not na- tural, but fuperadded. 8. The Tendon of a Mufch not in Action, is Will the fame ; but the Belly fofter, redder, laxer, longer, and flatter ; and this ftate of a Mufch is call'd its RcJiitutio?7 t tho it is ufually owing to the con- trary Action of its Antagonist ; for that being fruWrated, the Contraction of the other continues, as not being balan- ced by the Action of an Aniagonift. 9. If one AntagoniW: remain at ReW while the other is in Action, the Member in that cafe will be bent ; if both act at the fame time, it will be fitf'd and immoveable ; if neither act, it will be in- different, and ready to be moved whither the leafi excefs /hall carry it. ic All thefe Changes mentioned in the 7th, Sth, and 9th Articles, are performed in the fmaileft Moment of Time, and in the whole Mufch at once ; fo that they can pafs and repafs reciprocally without leaving any Trace in the Body behind them. ir. By injecting warm Water into the Artery of a quiefcent Mufcle, even that of a dead Car- cafs ; its Contraction is reWored ; and that long after Death. 12. The Bulk of a Mufcte is increafed rather than dimini- shed by every Experiment of its Contraction. 13. A Limb being bent, by fome external force, againft the Will, the Flexor Mufch of that Member affumes a Wate of Con- traction, as if it acted by its proper Motion ; tho not alto- gether foftrenuoufly. 14. The Wilt remaining indifferent, all the voluntary Mafchs, and all their Veffels are equally Full, and moved by the Blood and Spirits equably convey'd to 'em, and that throughout the whole Body at once.

For the sippli cation of this Smtflure of the Muscles, in ac- counting for the great Thxnomenon of Mufcular Motion, fee Muscular Motion.

As the Mufcular Fibres, or, which comes to the fame, the Fafciculi of Mufcular Fibres, have not always the fame Si- tuation with regard to each other, nor run in the fame di- rection, but fometimes run parallel to themfelves and their Tendons ; and are fometimesdifpofed obliquely both to their Tendons and to each other : hence there arifes two different kinds of Mufcles.

The one Direct and Parallel, which fome call Simple Mufchs,

The other Inclined, or Oblique ; call'd Compound Mufcles.

(6ot )

MUS

Under thefirrt of thefe kind, are included feveral other Specie* 5 for, firfi, Either the flea, Fibres run (irait from

e>ivte See Recti, Orbicular.es ?Jc.~

7 he fecund kind alio includes various Species.accordfng tB the various Angles which the oblique Fibres make with the Tendonsj fome inclining equally to each Tend™, fo as to

0. m a Rhombus, or acute angled Parallelogram with 'em, wSl^r call'd RLW„,«/,fa. others rifing from

WO parallel Tendons, are inferred obliquely ,n t o one corn- Don Tendon, as ,n the Buxpi of the Hand ; others, kOlv arifing from the Periphery of ,he Circle, concur in I Centre, and form M«fda call'd Radims. Sec Rhomboids*,

There are divers Species, and Divifions of Mufcles.

bum: Authors diitinguilh them into Mufcles of Voluntary, andot Involuntary or Natural or Necefiry Moth,,.

IhsMuJcksof Inwhmiry, or Necejjbry Morion, have their contracting and extending Powers within themfelves, and have no Amagcnilt ; fuch are the Hem and IWfuppofed to be. bee Heart and Lungs. •

"The Mufch! of Voluntary JlVion.which we more peculiarly denominate M-felei,tu.6 which are thofe we have here chiefly regard to, have each of 'cm their Antagonist Af«/I7e;,whicti act alternate!, in a contrary Direction ; the one being itretched and extended, while the other is contrattcd at the Morion ot the Will. See Motion.

The Mufcles have alio different Names from their diffe- rent Actions, Situations, Forms, &c. Thofe which ferve to move the fame Members contrary ways, are call'd An* tagmfis ; and thole that concur to the fame Aflion, fellows ot Pairs. See Antagon ist, &c. s

mgajirtis are thofe which have two Bellies ; Tmafirk; thole with three. See Digastric.

SfbixBers are thofe detiined to ihm feveral Apertures and Tallages in the Eody ; as the Mufcle at the Neck of the Bladder, and that of the Asm, which have the fame EffeS with the String of a Purfe to clofe thofe Parts. See Sphincter,

Some Mufcles have two or three Heads, call'd Biceps and Triceps. See BicErs, Triceps, Jifc.

We call Elevators thofe which lift up or raife the Parts ; Defreffovs thofe which move 'em downwards. See Ele- vator, £i?c.

Flexors thofe who bend 'em ; Extenfors thofe which flretch 'em out ; AiiuSors thofe which move the Parts in- wards ; AliuBors thofe which move 'em outwards ; Rota- tors thofe which move 'em round. See Flexor Ex- tensor, Abductor, Adductor, Rotator, ££c.

The Mufcles. base alfo different Names from 'their dif- ferent Figure ; fome refmbling a Batj fome a Lizard ; and fome a Turbct : Some are Triangular, others Square, others S;a!enous, others Pentagonal, others Pyramidal' Round, ($q. Whence come the Names of Deluides, Rbom'- boides, Scalenus, Trapezius, iye. See Deltoides, Sca- lenus, Trapezius,^.

Anaiomills are not agreed on the Number of Mufcles in the human Body; fome reckon 520; fome 44.tr ; and o- thers only 435. The Calculus, according to thefe latt is as follows :

Two of the Forehead; two of the Occiput; fix of the Eye-Lids ; twelve of the Eyes ; feven of the Nofe ; eightof the external Ear; four of the internal Ear ; thirteen of the Lips ; eight of the Tongue ; four of the Palate ; fourteen of the Larynx ; feven of the Pharynx ; ten of the Os Hyoi- des ; twelve of the Under- Jaw ; fourreen of the Head ; eight of the Neck ; eight of the Omoplates ; eighteen of the Arms; rwelve of 'the Elbows; eight of the Radii ; twelve of the Carpi ; forty eight of the Fingers ; fifty feven of ufe in Refpiration ; fix of the Loins ; ten of the Abdo- men; two of the Tefh'cles ; one of the Bladder ; four of thePe»is; four of the Anus ; thirty of the Thighs; twenty two of the Legs; eighteen of the Feet ; forty four of the Toes. The following Table of the Names and Offices of the feveral Mufcles in 'the Body, is extracted from Dr.Keil.

A TABLE of the Muscles from Dr.Kefl.

Frontales, they pull the Skin of the Forehead upwards, Qccip-.tales, pull the Skin of the Hind-head upwards. Altollens "), . , DeprimensS / "'" mhmm - Interims Malleoli, dillends the Tympanum. Extermis Malleoli, relaxes theTympanttm. Olliquus Malleoli.

Mufculus Stapidis, moves the Stirrup. Corrupter Supercilii.

LeBus Paipcbr* fuperioris, lifts up the Tipper Eye-Lid. Orbicularis Falpebrarum, fhuts both Eye-Lids.

7 Jtttltatj