| OCR Text |
Show 282 MR. P. G. PARSONS ON T H E [Mar. 20, ilium just external to the synchondrosis. Its arrangement is very constant. Muscles of Posterior Extremity. Gluteus Maximus, Tensor Fascice Femoris, and Sartorius.-These three muscles in Rodents are so closely united that they form practically one sheet, which rises from the anterior extremity or crest of the ilium, and from the fascia over the gluteus medius by which they are connected to the spinous processes of the posterior lumbar, sacral, and anterior caudal vertebrae. Occasionally it also rises from the outer part of Poupart's ligament and the inferior border of the ilium. The fibres which rise most anteriorly cross the front of the thigh obliquely, and are inserted into the fascia above and to the inner side of the patella; these fibres correspond to the sartorius. The fibres rising behind these run down the outer side of the thigh and are inserted into the fascia, there forming the tensor fasciae femoris. The rest of the muscle, or the gluteus maximus proper, is inserted partly into the fascia of the outer side of the thigh, and partly into the femur, sometimes quite high up, at others near its lower end. The nerve supply of these three muscles is the superior gluteal. In the Dipodidae few, if any, fibres were noticed going to the femur (Dipus cegyptius). In tbe Octodontidae the sartorius is well developed, reaching to the patella, while the bony insertion of the gluteus maximus is into the posterior surface of the femur at the junction of the middle and lower thirds (Myopotamus, Capromys, Pilorides, Aulacodus). In the Hystricidae the arrangement is the same, except in Sphingurus, in which the insertion of the gluteus maximus is into the middle of the femur (Hystrix cristata, Sphingurus, Erethizon dorsatus*). In the Chinchillidae and Dasyproctidae the arrangement is the same (Chinchilla, Lagostomus, Dasyprocta cristata, Ccelogenys). In the Caviidae the gluteus maximus has the same bony attachment as in Sphingurus (Cavia cobaya, Ceredon rupestris). Among the Sciuromorpha the sartorius rises from the outer part of Poupart's ligament and runs to the inner side of the knee, where it blends with the gracilis in Sciurus, Spermophilus, and Pteromys oral. The gluteus maximus is inserted by two slips, one into the third trochanter, the other into tbe lower part of the femur. It also has, of course, the usual fascial insertion. In Xerus the arrangement is the same, except that the gluteus maximus has its bony insertion into the junction of the upper and middle thirds of the femur. In Arctomys marmotta this muscle is inserted into the third trochanter and fascia. In Castor canadensis no sartorial portion was seen, the gluteus maximus being inserted into a ridge halfway down the femur. 1 P. Z. S. 1882, p. 271. |
