An introduction to the osteology of the Mammalia : being the substance of the course of lectures delivered at the Royal college of surgeons of England in 1870 / By William Henry Flower.

  • William Henry Flower
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the osteology of the Mammalia : being the substance of the course of lectures delivered at the Royal college of surgeons of England in 1870 / By William Henry Flower. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    The modifications with regard to the anterior extremity are that the humerus may be quite horizontal, or its distal ends may incline upwards, or, as is much more frequently the case, it may incline somewhat downwards, so that the dorsal surface is posterior and the ventral surface anterior : the fore- arm in the ordinary resting position may be quite vertical, or inclined with its upper end backwards : the whole of the manus may rest entirely on the ground, as in the so-called plantigrade or rather palmigrade animals, or the ])roximal part, the tarsus and metatarsus, may be raised and ]:)laced more or less vertically, the limb resting either on all or only on the terminal phalanges, according to the com- pleteness of the digitigrade mode of progression. Similar modifications apply to the hind limb. The femur is usually inclined with its distal end downwards, so that the dorsal or extensor surface is anterior, and the ventral or flexor surface posterior. In the Elephants it is very nearly vertical. In most animals which occasionally assume the upright position, as the Kangaroos and some Rodents, the femur is ordinarily inclined upwards at its distal extremity, so that the knee is above the acetabulum, and the pelvis slung as it were between the two hind limbs. In Man, on the other hand, in standing or walking the femur is nearly vertical with the distal end downwards, and the pelvis is supported on the top of the limbs. The positions of the limbs which are quite exceptional are those of certain aquatic animals. In the Cetacea (Fig. h) none of the segments of the anterior limb undergo any deflection from the primitive straight condition, nor is there any rotation of the bones of the forearm. The only changes which take place are a partial rotation backwards from the shoulder, and a slight turning downwards of the preaxial border. In the Sirenia and the