OCR Text |
Show 1867.] MYOLOGY OF IGUANA TUBERCULATA. 791 by the spine of the pubis, to the ischiatic symphysis. It is inserted into the summit of the trochanter below, and superficial to, the other two portions (fig. 17, Pc. 1). (2) The second part (fig. 17, Pc. 2) arises from the down-turned lip of the pubis, from the acetabulum to the symphysis. It is inserted immediately beneath the preceding portion. (3) The third part (fig. 17, Pc. 3) arises from the symphysis pubis, backwards to the middle of the obturator foramen. At the posterior end of its origin the obturator externus is superficial to it and overlaps it. It is inserted into the summit of the trochanter immediately behind the second part. The adductor magnus (figs. 14 & 17, ^4.) is a rather large muscle, which arises, by strong tendinous fibres, from the anterior part of the strong tendinous arch before mentioned which ends in front at the pubic spine. It is inserted into the inner side of the shaft of the femur (for about the second and third fifths of its vertical extent) between the vastus externus and the vastus internus. Rectus femoris (figs. 13, 14, 16 & 17,R.Fi). This muscle arises, by a very strong and rather broad tendon, from the ventral side of the acetabulum. It blends with the other extensors of the leg and with the aponeurosis of insertion of the gluteus maximus. Vastus internus. A rather small muscle (figs. 14 & 17, V. I.) arising from the inside of the shaft of the femur, about as high as the bottom of the uppermost third of the insertion of the adductor; below it blends with the crureus and other extensors of the leg. Vastus externus (fig. 15, V. Ex.). This .is exceedingly small, and so intimately connected with the crureus as scarcely to admit of definition. It arises from the lowest two-fifths of the postero-external surface of the shaft of the femur, and is inserted with the rest of the extensor mass. Crureus (figs. 16 & 17, Ci). This muscle is so intimately connected with the last as to be separable from it only with great difficulty. It arises from the front of the femur, its origin extending up near to the head of the bone. It is inserted into the patella along with the rest of the extensor muscular mass. At its summit it is, in part, continuous with the fourth portion of the iliacus. Gluteus maximus (V). A muscular layer, which may perhaps represent the gluteus maximus of mammals*, arises by a very strong tendinous fascia from the outer side and upper margin of the ilium. It covers the antero-external side of the thigh, becomes intimately united with the rectus femoris, and is inserted by aponeurosis into the outer surface of the vastus externus (figs. 13, 14, 15 & 16, G.Mxi). The gluteus medius arises from the outer surface of the ilium, between the origins of the gluteus maximus and ilio-peroneal. It is a small muscle, and is inserted into the outer side of the upper part * I a m very doubtful as to whether this muscle and the next are really glutei; but the condition of these muscles in Echidna inclines m e to name them so, provisionally at least (see Trans. Linn. Soc. vol. xxv. 1866, p. 391, and pl. 53. fig. 2. Cr. mx. and G. mdi). |