I N T 



are all direfted backwards. On the pofteri«r fiirface the 

 firll interofleiis is fubcutaneous : the others p.re covered by 

 thin aponeurofcs attached to the correfuondino^ metacarpal 

 bones, feparating the intcroflTei from the exteiil'or tendons, 

 and in tlicir intervals from the integuments. Their expanded 

 tendons are placed between the phalanges and the ikin. 



Thefe mufcles fcem to perform, as their primary ufe, the 

 abduction and adduAion of the fingers. They ferve to fix 

 the extenfor tendons ; which, not being covered by any 

 fibrous (iieaths, required this lateral fupport. They partake 

 this sffice with the inmbricales ; when the two interolfei of 

 any finger adt together, the extenfor tendon is drawn in the 

 diagonal of their direftion. If the fingers are extended, 

 they will be fixed more firmly in this pofition ; but if they 

 are already bent, the flexion is incrcafed by the action of the 

 interon'ei, which exert themfelves fo much the more efiec- 

 tUuUy, as their tendon falls perpendicularly in the moving 

 part. From the courfe which the tendons purfuc, along the 

 fides to the backs of the fingers, they will have the effect 

 of extending the middle and lall joints. If the fingers are 

 fixed, thefe mufcles may bend the metacarpus to them. 



The interojja of the foot hold the fame relation to the 

 metatarfub, as thofe of the h md do to the mstacarpus ; and 

 a;-e arranged into an internal and an external clafs, or a fu- 

 perior and an inferior ; of wh.ich the former is placed to- 

 wards the back, and the latter towards the fole of the foot. 

 They are the addudtors and abduftors of the toes ; and are 

 feven in number, three internal, and four external. Of thefe, 

 fix belong to the three middle toes, and one to the little toe, 

 their place being fupplied, in the great toes, by its proper 

 mufcles. 



The internal interqfii are the adductors of the third, 

 fourth, and fifth toes. Tliey agree very nearly in their 

 mode of origin, figure, courfe, termination, ar.d action. 

 They are fmall and tendinous at their commencement ; grow 

 gradually thicker and broader, then again decreafe, andform 

 long and flat tendons at the digital end of the metacarpus. 

 They all pafs forwards from the metatarfus towards the toes, 

 and end at the tibial fides cf the metacarpal extremities of 

 their refpective toes, near the terminations of the lumbri- 

 cales. Their tendons are clofely connedted to the capfules 

 of the firll joints of the toes, to thofe of the lumbricales, 

 and of the extenfors The firft arifes from the pofterior 

 part of the under lurface of the third metatarfal bone on its 

 tibial fide : the fecond from the corref|-onding part of the 

 fourth, and the third from that of the fifth metatarfal bojie. 

 The two latter arc a f o connected to the {heath which con-- 

 tains the tendon of tlie peix)neus longus. 



The externa! ir.terojfa are i and 2, the addwdtor and ah- 

 dactor of the fecond toe, 3, the abdudtor of 1 he third, and 

 4, the abdudtor of the fourth. The three latter refemble 

 each other, and refemble alfo the external interoiTei of the 

 hand, in having double origins : each of them has two heads, 

 arifing from the two contiguous metatarfal bones, tendinous 

 at their commencement, uniting at acute angles in a middle 

 tendon, which pafles forwards to the toes. The tendons are 

 thicker and broader than thofe of the internal interoflei, 

 connedted in the fame way to the capfules of the firll joints,. 

 a;id inferted in the fame manner, but on the oppofite fides of 

 the firll phalanges. The abdudtor of the fecond toe has its 

 larger origin from rather more than the poiterior half of the' 

 third metatarfal bone, on its outer or peroneal furface ; the 

 tmaller head conies from the oppofed furface of the fecend 

 bone. The .abdudtor of the third toe Has a larger origin 

 from the fourih, and a fmaller from tiie third bone ; and the 

 abdudtor of the fourth has the fame relation in its origin to 

 the fifth and fourth metatarfal bones. The adduftcr cf the 



I N T 



fecond toe differs from the other external or fuperiar inte- 

 rolfei, in arifing from one bone only : its origin is derived 

 from more than the pofterior half of the inner or tibial fur- 

 face of tl - fecond metatarfal bone : its infertion is fimilar to 

 that of the others. 



The interoflei of the foot have the following relations to 

 the furrounding parts: On the back of the foot tliey are 

 covered by the tendons of the two extenfors, and by a very 

 thin aponeurofis, which is fometimes fcarcely fenlible, anJT 

 whicii is extended in the intervals of the metatarfal bones. 

 In the fole they are in contadt with the mufcles of the great 

 and of the little toe, with the tendons of the flexor longus 

 digitorum and the lumbricales, and with the dcepfeated 

 plantar veflels. On their fides they correfpond to each 

 other, or to the metatarfal bones. 



The motions produced by thefe mufcles are analogous t-a 

 thofe of the correfponding ones in the hand. In the firlt 

 place they are adductors and abdudtors of their refpedlive 

 toes. They may adt as flexors of the firft phalanges 

 through the means of their tendons affixed to thefe bones, 

 more particularly when the firft joints are already fiightly 

 bent ; for they are then diredted obliquely or perpendicularly 

 to the moveable point, with which, in the extended ftate, they- 

 are parallel. By the portions, which they detach to the ex- 

 tenfor tendons, they may alTift the extenfion of the laft pha- 

 langes ; but it is neceffary that the e.x.tenfors fhould have 

 previoufly adted in fome degree, to carry the lail phalanx 

 upwards and backwards, and this motion is then incieafcd 

 by the inleroffci. They ferve alfo, as in the hand, to fix the 

 extenfor tendons laterally. 



INTEROSSEUS, an epithet of certain organs of 

 the body^ particularly in the fore-arm and leg, which are 

 fituated between two bones. The interoffeous artery of the 

 fore-ar.m is a branch of the ulnar, and is divided into an an- 

 terior and a pofterior interoffeous branch. In the leg, the 

 peroneal artery is fometimes defignated by this term. The 

 interoffeous ligaments are aponeurotic expanfions attached 

 to the oppofed edges of the bones of the arm and leg, and 

 filling up the intervals betv^ceen thefe bones. See Aiiteuy 



and EXTREMITIE.S. 



INTERPLEADER, Bill of, in Latu. is where a perfqn 

 who owes a debt or rent to one of the parties in a chancpry 

 fi'Jt, but, till the determination of it, he knov\'S not to which,. 

 defires that they may interplead, that he may be fafe in the 

 payment. In this laft cafe it is ufual to order the money to 

 be paid into court, for the benefit of fuch of the parties to 

 whom, upon hearing, the court IhaJl decree it to be due. 

 But this depends upon circumftances; and the plaintiff mull 

 alfo annex an affidavit to his bill, fwearing that he does not 

 collude with either of the partie- 



INTERPOLATION, a term ufed by critics in fpeak- 

 jng of ai.cient writings and manufcripts, in which fome ipu- 

 rious additions or alterations have been fince made. 



To eftablifh or afcertain an interpolation, P. Ruinart gives 

 as the five following- rules i. That the piece fuppofed to 

 be interp ilated appear to have all the antiquity it pretends 

 ti). 2. That there be good proofs that it has beea interpo- 

 lated. 3. That the fuppofed interpolations agree to the 

 time of the interpolator. 4. That tiie interpolations db not 

 touch the foun<iation of the work ;. r.ndtliat they be not too 

 frequent, nor entirely disfigure the. piece. 5. That the refti- 

 tution made, agree perfedlly to the reft of the work. . 



Interpolations iiave occafioiied feveralof the various read- 

 ings in the New Tcftament. Michaelis, in his " Introduce 

 tion tj the New Teftament," and alfo other writers, have 

 fuggefted how thef^were introduced, and how theymay<bfr 

 diilinguifhcd from the original text. E. G. If for a palfage 



that- 



