Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/247

 235 A N A T O M Y. a fmall infertion to the ligarnentum facro-fci&ticum and edge of the great finus of the cs ilium. ' TRICEPS PRIMUS. thence it runs tranfverfely towards the joint of This, with the two following tricipital mufcles, are theFrom hip, its fibres contrading in breadth, and ends in a flefny and flat, and of different lengths, fituated between fmall tendon, is inferted in the middle of the interthe os pubis and the whole length of the os femoris. labium of which the upper edge of the great trochanter, The firft and fecond crofs each other in fuch a manner, nal by two or three branches. as that the mufcle, which is the firfl: on the os pubis, . becomes the fecond on the os femoris; and the fecond OBTURATOR INTER NUS. on the os pubis, is the firft on the os femoris. The third mufcle keeps its rank. is a flat mufcle, almoft triangular, fituated in The triceps primus is fixed above by a ftiort tendon theThis bottom of the pelvis. It covers the forameri ovale, to the tuberofity or fpine of the os pubis, and to the all the infide of the os pubis and ifchium. neighbouring part of the fymphyfis, its fibres mixing a andItalmoft is fixed to the internal labium of all the anterior a little with thofe of the peftineus. From thence it runs half of the foramen a little to the neighbouring down, increafing in breadth, and is inferted by flefliy fi- part of the obturatorovale, ,; and alfo both above and* bres interiorly in the middle portion of the linea femo- below the foramen. Itligament is likewife fixed, to the upper half ris afpera. the infide of the 6s ifchium from the upper oblique At the lower part of this infertion, a portion of the ofnotch in the foramen ovale, to the mufcle feparates from the reft, and fends off a long ten- great pofterior finus of the os ilium. fuperior part of the don, which, together with a like tendon from the triceps From all this extent the flefhy fibres, contra<5ting in tertius, is inferted in the inner condyle of the extremity breadth, run down below the fpine of the ifchium, of the os femoris. where they go out of the pelvis through the pofterior notch of the ifchium, and afterwards unite in, one large flat tendon, which crofting over that of the pyriformis, TRICEPS SECUNDUS. unites with it, having firft received on each fide fome This mufcle is fixed above by fleftiy fibres, below additional flefli^ fibres from the two gemelii. the fuperior infertion of the triceps primus* in all the outfide of the inferior ramus of the os pubis, as low as GEMELLI. the foramen ovale, but feldom folow as -the ramus of the os ifchium. are to two fmall, flat, narrow mufcles, fituFrom thence it runs down, and is inferted in the upper atedThese almoft tranfverfely one above jhe other, between part of the linea afnera, between the peftineus and tri- the tuberofity of the ifchium and the great trochanter, ceps primus, mixing a little with each of thefe mufcles. immediately below the pyriformis, and parted by the tendon of the obturator intern us. The fuperior and fmalleft gemellus is fixed to the TRICEPS T^RTIUS. part of the fpine of the ifchium, to the fupenor This mufcle is fixed above by flelhy fibres to the an- lower part of the fmail ifchiatic notch, and to a rough line, terior part of all the fliort ramus of the ifchium, and to which runs crpfs the outfide of the ifehium, beginning a fmall part of the tuberofrty of that bone. fpine, and continued under the acetabulum, From thence it runs down, and is inferted by flefliy from the it is bent downward. fibres in the linea afpera, almoft from the little trochan- where The inferior gemellus is fixed to the futer, down to the middle of*the os femoris. It goes low- perior and backandpartlargeft of the tuberofity of the ifchium, er down than the firft triceps, fending off a feparate por- and to a rough impreflion which runs crofs the outfide tion like that of the mufcle laft mentioned. of the ifchium ffrom the lower extremity of the ifchiatic Thefe two portions join together, and form a com- notch, and is bent upward toward the other line, tomon tendon, which, running down to the lower extremi- gether - ty of the os femoris, is inferted in .the back part of the circle. with which it forms a fort of irregular femituberofity of the inner condyle. Both thefe mufcles have likewife a fmall infertion in the infide of the ifchium, where, being united together by a particular membrane, one of them joins the upper PYRIFORMISPYRAMIDALIS. fide, other the lower fide of the obturator interThis is a fmall oblong mufcle, of the figure of a flat nus, aandlittletheafter it has paffed over the notch: They pear or pyramid, from whence it has its name. It is inclofe it as in a bag, and continue to be fixed to it by fituated almoft tranfverfely, between the os facrum and fleftiy fibres all the' way to its extremity. ifchium, being covered and hid by the firft two glutaei. It is fixed to the inferior lateral part of the os facrum, OBTURATOR EXTERNUS. by flefliy fibres, and to the neighbouring'part of the anterior or concave fide of that bone, by three digitations is a fmall flat tnufcle,- which fills up the foralying between the anterior holes. It is likewife fixed by menThis ovale of the os innominatum exteriorly, and reaches Vol. I. No. 9. 3 3F from Part II.