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The motions produced by tlie nuifcles in this region are 

 the elevation and deprcflion ol' tiie ribf, wliich coincide with 

 jnfpiration nnd exfpii-atiixi. The agents of elevation are the 

 ievRtores and intevcolbii muicles, bclides other auxiliary 

 powers. The fori;T:'-, tixcd to the tranfverfe procetTes, 

 which are immoveable, can obvioully exert their adion 

 only on the ribs, whicli lliey elevate and carry outwards. 

 Thus they increafe tlie tranfverfe diameter of the cheft, par- 

 ticularly at its lower part, where, on one hand, the mufcles 

 are much llronger, and on the other, in confequence of the 

 greater mobihty of the lower ribs, the refinance to be 

 overcome is much lefs. The aftion of the intercoftals in 

 elevating the ribs is much favoured by the mode of attach- 

 ment of the tirll and fecond of thefe bones. They pofFefs 

 but little power of motion, and therefore form a fixed 

 point, to w hich the others can be elevated. They arc more- 

 over (lill further fixed, pt^rticnlarly in deep infpirations, by 

 the fcaleni, which may carry them in a flight degree up- 

 wards. Both flrata, although the direfiions of their 

 fibres are fo different, aA equally as elevators : in faft, as 

 the upper part of the cliell is fixed, the lower portion mull 

 be moved by thefe powers. In great infpirations, other 

 mufcles attached to the cheft, as the peftorales, ferrati. Sec. 

 afllll the levatores and intercoftal mufcles in elevating and 

 turning outwards the ribs. 



The depreflion of the ribs, or their reftoration from the 

 elevated to their former ftate, is nearly a paffive motion : 

 it depends, in the firft place, on the relaxation of the ele- 

 vating powers, and then on the elafticity of the cartilages 

 connefted to the fternum. Thefe are twilled in the act of 

 elevation, and immediately recover iherafelves when this 

 force ceafes to act. When the depreflion is more con- 

 fiderable, as in coughing, in difficult expecloi-ations, in 

 fneezing, cafes in which a ftrong exfpiration is required for 

 the purpofe of expelling much air from the cheil, an aclive 

 power is exerted for drawing down the ribs. The triangu- 

 laris fterni, which has its fixed point in the fternum, de- 

 prefTes the cartilages of the true ribs. The abdominal 

 mufcles fix below the loofe edges of the falfe ribs, which 

 thus become a fixed point to which the other ribs may be 

 deprefied by the intercoftal mufcles. Thus thsjattcr muf- 

 cles are elevators or depreiTors, according as the fixed point 

 is above or below. Moreover, the quadratus lumborum 

 holds down firmly the laft rib ; and bears the fame relation 

 to that bone in great exfpirations, which the fcaleni do to 

 the two firft ribs in deep infpirations. The ferratus 

 inferior pofticus aflifts the abdominal mufcles on thefe oc- 

 cafion^. 



The intercoftal mufcles and the diaphragm feem to form 

 an exception to that general law of the voluntary mufcles, 

 by virtue of which, any mufcle after long exercife goes into 

 a ftate of fatigue, requiring for the reparation of its power 

 an intermiflion of atiion, which may be particularly ob- 

 ferved in fleep. Now the motions of the cheft, beginning 

 and ending with life, are never interrupted. Thio exception 

 is only apparent ; each contraftiou is fucceeded by a pro- 

 portionate relaxation, fo that the time of inactivity of the 

 peftoral mufcles equals that of their active ftate. More- 

 over, the diaphragm and intercoilals mutually fapply each 

 other's places : both are faid to be employed in infpiration, 

 but fomctimes one and fometimes the others are more ac- 

 tively concerned ; fo that we may confid.-r them in fome 

 -degree as alternately acting and refting. The ir.tercollals 

 appear to be the moft concerned duriug ilcep, and the 

 diaphragm in the waking ftate. Indeed a confiderable con- 

 traction of the latter, in forae meafure, oppofes that of the 

 Invcr inlcrcoftals, fince it tends to contract tlie lower cir- 



1 N T 



cumference of the cheft which the others enlarge. The 

 two ftrata of the intercoftals may contract feparatelv ; thus 

 one may reft while the other is employed. Laftly, the leva- 

 tores may alternate with the latter mufcles : thus, although 

 the motions of the cheft are conftant, thoir agents, like all 

 the other mufcles of the animal life, may be fubjetted to 

 the law of intermiflion of aftion. Hence, if rcfpiration i.i 

 confiderably hurried, and all the infpiratory mufcles are 

 brought into a<£lion, they are aflcftcd wilh a real laffitude, 

 and at laft cannot coutradl without difficulty. In running, 

 where the blood is carried in great ahundai.ce to the heart, 

 and muft pafs quickly through the cheft, we ixioji lofe breatii ; 

 which is merely experiencing a difficulty in contrafting tlir 

 tired m.ufcles of uifpirali u. Refpiration is then intti- 

 rupted, as locemotion would be by a fatigued ftate of th" 

 mufcles of the lower extremities ; and this may even go fo 

 far as to produce a real immobility of the inipiratory muicles. 

 a ftate, which though not dangerous in otlier inltances, m 

 in the organs ot locomotion for example, is fatal in the refiK- 

 ratory mufcles as it iiifpcnds breathing. Examples of ani- 

 mals, and even of men falling fuddeiily dead after great ex 

 ertions in running, are not extremely rare. Death occurs iu 

 thefe inftances, as when the phrenic nerve or the fpinal mai row.': 

 is divided. Thofe affections of the cheft, in which relpira-: 

 tion-'.s hiu-ried for a certain time,occafion at laft a real laffitude 

 of the peftoral muicles ; and tlie difficulty of breathing 

 produced by this tired ilate of the moving or_ans, fuccecding 

 to that produced by the difeafe itfelf, prolongs the painful 

 fenfation of fuffocation. We mull diftinguifti, in tiiefe cales, 

 what belongs to the lung, from that which arifes from the 

 mufcles. After certain hyilerical attacks, in which the dia- 

 phragm and intercoftal mufcles liave been violently agitated, 

 a real fenfe of fatigue is experienced in the cheft, which can 

 only be moved with difficulty, and not to a fuificient extent 

 for the production of loud founds, a phenomenon which may 

 be obferved alfo after exertion in running. The mufcles 

 require reft before they can expel air m a quantity capable of 

 producing ftrong and diilinft founds. 



IxTEUCOST.'VLKS Arter'is, arteries which run in the inter- 

 vals of the ribs :. the iniercoftales vense are veins corre- 

 fponding to thofe. See Artery and Vox. 



IxTEKf.O.^TALES Nervi, are the branches of the fpinal 

 marrow in the back, which accompany thefe arteries and 

 veins.- The epithet hiurcnjlala is fometimes alfo applied to 

 the great fympathetic nerve. See Nerve. 



INTERCUS, a word ufedby fome medical writers, to 

 exprefs that fort of dropfv more ufuallv called an anafarca. 

 IN rERDICT, a cenfure inflicted by a pope, or bifliop, 

 fufpending the priefts from their functions, and depriving 

 the people of the ufe of facraments, divine fervice, and 

 Chriftian burial. 



In common law, interdift is alfo ufed iu the fame fenfe 

 as in the canon law ; where it is defined to be, " cen- 

 fura ecclefiaftica prohiben? adminiftrationem divinorum." 



Interdict is moft properly underftood of a general ex- 

 communication of a country, or city, as appears by the 

 Decretals. See ExcoAtMuxicwTiox. 



There is a local and a /i^'/yina/interdift : where thefe two 

 are joined, the interdift is faid to he mixed. 



This puniftiment, as well as general excommunication-, 

 were but little known till the time of pope Gregory VII, 

 In the year 1169, pope Alexander III. put aU England 

 under an interdict, forbidding the clergy to perforin any 

 part of divine fervice, except the. baptizing of infants, 

 taking confeffion, and giving abfolution t? dying peni-. 

 tents. 



In escommunicating. a prince, aU his adherents, that is, 



.hii 



