Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/254

 2 12 A N A T O M Y. Part II. When this tnufcle is carefully examined, we find that the fame time that it bends it, when it’afts without the it is fixed, by a'very fiiort common tendon, to the outfide alfiftance of the tibialis anticus. of the bafis of the firft phalanx of the great toe, con- The peronaeus minimus is an afliftant to the medius in jointly with the antithenar; and, by three different por- the flexion of the foot, in preferving the asquilibrium of tions or digitations, to the three interoffeous ligaments the leg, and in turning the foie of the foot outward. which connect the heads of the four metatarfal bones The gaflxocnemii and foleus make a kind of triceps; next the great toe, laterally to each othe^. and, by their common tendon, extend the foot, and keep it extended again!! the ftrongeft refillance. It is by their means that we raife the whole body, even with an addiINTEROSSEI. tional burden, when we Hand a tip-toes; and that we These are feven fmall mufcles which fill up the four walk, and jump. interftices between the metatarfal bones, much after the Therungaftrocnemii, their infertion in the os femoris, fame manner as in the hand. The four largefl: are fu- may, in great efforts,bymove the leg on the thigh, and perior, the other three inferior. the thigh on the leg, as afliftants to the biceps, femimembranofus, femi-tendinofus, gracilis internus, and fartorius. METATARSIUS. foleus, by the multitude of its flefhy fibres and This is a flelhy mafs, lying under the foie of the its The ftrudfure, is more proper for ftrong than foot. It is fixed, by one end, in the fore-part of the largepenniform motions, and feems principally to fuftain the gagreat tuberofity of the os calcis; and running forward ftrocnemii in the motions begun by them. The tendifrom thence, it terminates in a kind of fhort tendon, portions of this mufcle and of the gaftrocnemii, tho’ which is fixed in the tuberofify and pofterior part of the nous they form a ftrong tendon all together, i'eem neverthelefs lower fide of the fifth bone of the metatarfus. to Aide a little upon each other in the different flexions and extenfions of the foot. Anatomifts are not agreed with regard to the ufe of P A R A T H E N A R MAJOR. tibialis gracilis. This is a pretty long mufcle, forming part of the theWhen the tibialis pofticus adts alone, it extends the outer edge of the foie of the foot. foot obliquely inward. When it adts together with the It is fixed backwards by a flelhy body, to the outer part gaftrocnemii it changes the ftreight diredtion of the lower fide of the os calcis, from the fmall polleri- of their motionandtofoleus, one. When it adts with or external tuberofity, all the way to the anterior tubero- the tibialis anticus, antheoblique foie the foot is turned more fity. There it joins the metatarfius, and at the bafis of the •diredtly inward, or toward theof other foot. fifth metatarfal bone feparates from it again, and forms When the peronasus longus or maximus It a tendon, which is inferted in the outfide of the firft pha- may extend the foot hanging freely in the airadts; alone, then lanx of the little toe, near its bafis, and near the infer- this extenfion is obliquely outward. Together but with the tion of the parathenar minor. gaft rocnemii and foleus, it likewife changes their diredtion to an oblique extenfion outward. The extenfor pollicis longus extends the two phalanPARATHENAR MINOR. ges the great toe; and it may likewife be an afliftant This is a flelhy mufcle, fixed along the pollerior to theof tibialis anticus. half of the outer and lower fide of the fifth bone of the The flexor pollicis longus not only bends the fecond metatarfus. It terminates under the head of that bone, phalanx of the great toe, likewife ferve, in great in a tendon which is inferted in the lower part of the efforts, as an afliftant tobutthemayextenfors of the tarfus. bafis of the firfl: phalanx of the little toe. This mufcle is of great ufe in climbing up a fteep place. The thenar bends the firft phalanx of the great toe. the portion neareft the inner edge of the foot eiUses of the Mufcles which move the Tarfus and the When ther adts alone, or adts more than the reft, the great toe other Bones of the Foot. is feparated from the other toes, efpecially if it be at the The tibialis anticus bends the foot, that is, turns the fame time extended. ’ point of the foot toward the leg ; which motion is per- The antithenar, adting with the thenar, bends the firft formed by the ginglymoid articulation of the aftragalus phalanx of the great toe. When it adts alone, efpeciwith the tibia and fibula. It likewife bends the leg on ally if the great toe is bent, it brings it nearer the other toes, in proportion to the degrees of action of its the foot, or hinders its extenfion. By its lateral infertion in the os cuneiforme maximum, different portions. it moves this bone in particular over the anterior extre- The two extenfores digitorum communes concur in exmity of the os calcis; by which the foie of the foot is tending the four fmall toes ; and, as the extenfor longus is not near fo flefhy as that of the hand, this difference is turned inward toward the other. The peronseus medius bends the foot, and hinders the made up by the extenfor brevis. The longus alone leg from falling back in the fame manner as the tibialis' feems to extend the firft phalanges; and they both join apticus. By its infertion in the tuberofity of the fifth in the extenfion of the fecond and third phalanges ; the metatarfal bone, it turns the foie of the foot outward at brevis, by the obliquity of its diredtion, moderating the