OCR Text |
Show 478 DR. R. W. SHUFELDT ON [Nov. 16, muscle being thin and closely pressed to the pelvis. The fibres converge as they near the femur and terminate in a strong, flat tendon which becomes inserted on the outer aspect of the trocbanter of that bone, which insertion is slightly overlapped by the tendon of the gluteus medius muscle. The adductors arise from the infero-external margin of the ischium, between the anterior edge of the semimembranosus and the obturator foramen. The adductor longus (Plate X L V . fig. 1, a.l) is the more anterior of the two and consequently arises the higher on the pelvis, and comes off in front of the adductor magnus, which it largely overlaps. Its fibres pass obliquely to the posterior aspect of the shaft of the femur, down which they become inserted as far as its middle, along the linea aspera, a line which is well marked in our subject. The adductor magnus (Plate X L V . fig. 1, a.m), like the one just described, is also a broad ribbon-like muscle, arising from the ischium between the semimembranosus and a middle point on the underside of the adductor longus, close up to its semitendinous origin. Anteriorly its margin is free, while posteriorly it is juxtaposed to the anterior border of the semimembranosus. Passing parallel with those of the other adductor, its fibres are inserted into the distal moiety of the linea aspera of the femoral shaft, down to the intercondyloid notch of that bone, where this muscle makes a very substantial insertion. Removing all the muscles of the thigh thus far described, we find that in this region we have the following ones remaining. They are shown in my drawing (Plate X L V . fig. 2), together with a few as yet undescribed muscles of the leg. A very important muscle is the obturator interims (Plate X L V. fig. 2, o.i), and in Geococcyx it exists as we find it in the majority of the class. Prof. Garrod laid some stress on the point whether this muscle arose from a triangular or an oval area. Here it arises from a decidedly oval one, and as usual this is from the mesial surfaces of the ischium and the post-pubic element of the pelvis. Its tendon emerges from the obturator foramen, and overlapping the gemellus muscle, passes to the outer aspect of the upper part of the trochanter of the femur, where it is inserted. The gemellus (Plate X L V . fig. 2, ge) is a short, thick, carneous muscle, which arises about the outer rim of the obturator foramen of the pelvis. Its fibres passing obliquely upwards and forwards are inserted with the tendon of the obturator internus muscle on the trochanter of the femur. This bird also has a few of the fibres of its gemellus muscle inserted into the tendon of the obturator externus muscle, at least I found this to be the case in the specimen before me. W e find the vastus internus (Plate X L V . fig. 2, v.i) to be a strong, fusiform muscle, that is only fully discovered after we have removed the ambiens and the adductors. It lies on the postero-internal aspect of the shaft of the femur, arising from the linea aspera nearly as high up as the head of that bone, and increasing in bulk as it descends, still making attachment to the linea aspera, it only becomes free just above the condyles. At this point it terminates in a flat tendon, which, crossing the articulation of the knee, becomes inserted into the |