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Show 266 MESSRS. B. C. A. WINDLE AND F. G. PARSONS ON [Nov. 3, which comes off the sciatic outside the pelvis and below the point of origin of the superior gluteal. Femoro-coccygeus {Agitator caudce).-This muscle can be made out readily enough in most Ungulates by anyone who is familiar with it and who appreciates the fact that it is the part of the great muscular sheet which lies between the ectogluteus and biceps. The origin is from the posterior sacral and anterior caudal spines, and the insertion chiefly into the outer side of the patella; above and below this it blends with the fascia (see text-fig. 24). As this muscle was not known by most of the older writers on myology, its description is often included with that of the ectogluteus or biceps. W e believe that it is present in every Ungulate, and that its attachments are very constant. It is supplied by the same nerve as the ectogluteus. Tensor fascice femoris.-As the femoro-coccygeus connects the ectogluteus and biceps, so the muscle under consideration lies between the ectogluteus and sartorius though it is often separated by a good interval from the former. It rises from the iliac crest, which of course is a short structure, and spreads out into a fan-shaped muscular mass which usually becomes lost in the fascia lata about the middle of the thigh. In the Elephant (79, 81, 84), however, it runs two-thirds of the way down, while in the Tapir (61, 62) it is fleshy as low as the outer side of the patella. Pater-son and Dun have noticed in the Elephant (85), and Murie in the Giraffe (33), that the fascia lata on the outer side of the thigh is elastic. Its nerve-supply is the superior gluteal. Mesogluteus {Gluteus medius).-This muscle, as is usual in mammals, is generally larger than the ectogluteus; it rises from the greater part of the gluteal surface of the ilium as far as the margin of the great sciatic notch, as well as from the fascia covering the muscle. At its origin it is probably inseparably blended with the pyriformis, at all events the latter can never be traced to its human origin from the ventral side of the sacrum. The insertion of the mesogluteus is into the great trochanter on its outer and often also on its posterior surface. It is supplied by the superior gluteal nerve in the Pig, Sheep, Antelope, and Horse, but in the Harnessed Antelope (55) w e also found a small twig passing to it from the inferior gluteal. In the Perissodactyla the muscle seems specially large, and its origin creeps along the fascia lata covering it to the sheath of the erector spinas and the sacroiliac and sacro-sciatic ligaments. Meckel (VII.) says that in the Horse it is twelve times as large as the ectogluteus, and it is also very large in the Tapir. In the Pig and Hyrax it is relatively much smaller, and Meckel describes it in the latter animal as being absolutely smaller than the ectogluteus. In our specimen of Hyrax (75) we do not feel justified in going as far as this, but the muscle was certainly very thin in the middle. Entogluteus {Gluteus minimus).-This is also a large muscle, but its exact attachments are difficult to define owing to the fact that it is often closely connected with the gluteus ventralis. We |
