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 Part D. A N A T O M Y. 213 action of the longns, which otherwife would have turned edge of the middle aponeurofis, and by the other to all the bafis of the cavity of the thorax, being inferred the toes obliquely the contrary way. The perforatus or flexor digitorum brevis^ bends the by digitations in the lower parts of the appendix of the fecond phalanges; and the perforans or flexor longus, fternum, of the loweft true ribs, of all the falfe ribs, the third; the ufe of thefe mufcles being nearly the fame and in the neighbouring vertebrae. with thofe of the perforatus and perforans of the hand. We have therefore three kinds of infertions ; one fter-. - The flexor accefforius is an afliftant to the perforans, nal; twelve coftal, fix on each fide; and two vertebral, increafing its force on fome occafions. It likewife di- one on each fide. Thefe laft are very fmall, and fomerects the tendon of that mufcle ; for by contracting, at times fcarcely perceivable. The coftal infertions join the fame time that the flefliy belly of the perforans is in thofe of the tranfverfalis abdominis, but do not mix with adlion, it makes the tendons go in a ftraighter line to the them, as they feem to do before the membrane which toes than they would otherwife do, becaufe of their obli- covers them is removed. quity. . The fibres inferred in the appendix enfiformis, run The lumbricales have nearly^the fame functions in the from behind direftly forward, and form a fmall parallel foot as in the hand; and they are partly aflifted, and plane. partly directed, by the flexor acceflbrius. The firft coftal infertion runs a little obliquely toThe interoffei of the foot have the fame ufes as in the wards the cartilage of the feventh true rib, a triangular hand. The firft fuperior mufcle brings.the fecond toe fpace being left between this and the fternal infertion, at neat' the great toe; the other three bring the fecond, which the pleura and peritonaeum meet. The infertion third, and fourth toes near the little toe. The three of thefe fibres is very broad, taking up about two thirds inferior mufcles move the laft three toes toward the other of the cartilage of the feventh rib, and a fmall part of two. the bone, from whence it reaches beyond the angle of The metatarfius moves the lall bone of the metatarfus, the cartilage. much in the fame manner as the metacarpius does that The fecond infertion is into the whole cartilage of the. of the metacarpus. firft falfe rib; the third partly in the bone, and partly The tranfverfalis may aflift the metatarfius in this in the cartilage of the fecond falfe rib; the fourth in aftion, which is fuppofed to be of ufe to'tilers ih climb- the bone, and fometimes a little in the cartilage of the ing. The antithenar may likewife concur, and the pe- third falfe rib; the fifth in the bone, and a little in the ronaeus minimus may ferve to counterbalance thefe muf- cartilage of the fourth falfe rib, being broader than the cles, and to bring the metatarfus back to its natural fi- reft. tuation. The fixth is in the cartilage of the laft falfe rib, and The parathenar major ferves particularly to feparate ahnoft through the whole length of the bone. At the the little toe from the reft; and the parathenar minor head of this rib, it joins the vertebral infertion, which bends the firft phalanx of that toe. runs from the lateral part of the laft vertebra of the back, to the firft vertebra of the loins. The fmall mufcle of the diaphragm is thicker than the Sect. XIII. T^he Muscles employed in other, but of much lefs extent. It is fituated along the forefide of the bodies of the laft vertebra of the Refpiration. back and feveral of thofe of the loins, being turned a little to the left hand. It is of an oblong form, reprefentDIAPHRAGM A. ing in fome meafure a flefliy collar, the two lateral porThis is a very broad and thin mufcle, fituated at tions of which, crofs each other, and afterward become the bafis of the thorax, and ferving as a tranfverfe tendinous toward the lower part. partition to feparate that cavity from the abdomen'. The upper part of the body of this mufcle is fixed in For this reafon the Greeks termed it diaphragma ; and the Hope of the middle aponeurofis of the great mufcle. and the Tuntms, feptum tranfverfum. It forms an oblique The outer edges of the ake or lateral portions join the inclined arch, the fore-part of which is higheft, and the pofterior plane of the great mufcle, and thefe portions pofterior part loweft, making a very acute angle with adhere to the body of the laft vertebra of the back. the back. The extremities, called likewife pillars or crura, are. It is looked upon as a double and digaftric mufcle, inferted by feveral tendinous digitations in the vertebrae made of two different portions, one large and fupe- of the loins. rior, called the great mufcle of the diaphragm; the o- The upper part of the flefliy body is formed by a parther fmall and inferior, appearing like an appendix to the ticular intertexture of fibres belonging to the two ala:. other, called the fmall or inferior mufcle of the dia- Thefe two aloe, whereof that toward the right-hand is gephragm. nerally the moft confiderable, part from each other, and The great or principal mufcle is fleftiy in its circum- form an oval hole, terminated on the lower part by ference, and tendinous and aponeurotic in the middle, fibres, detatched from the infide of each ala, immediately which, for that reafon, is commonly called centrum above the laft vertebra of the back. Thefe fibres denervuum five tendinofum. cuffate and crofs each other, and afterwards thofe that The flefliy circumference is radiated, the fibres of come from each ala join that on the other fide, fo that which it rs made up being fixed by one extremity to the each of the crura is a produdticn of both ake. Vot. I. No. 9. 3 The 3H