Observations on the limbs of vertebrate animals : the plan of their construction, their homology, and the comparison of the fore and hind limbs / by George Murray Humphry.

  • Humphry, George Murray, Sir, 1820-1896.
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the limbs of vertebrate animals : the plan of their construction, their homology, and the comparison of the fore and hind limbs / by George Murray Humphry. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    17/54 (page 13)
    tibia—forms the medium of connexion between the femur and the tarsus. The other bone —thefbula—bears very little weight; its chief office is to extend the surface for the attach- ment of muscles. In no mammal does it reach the femur; and in all placental mammals it is articulated only with one bone of the tarsus, viz. the side of the astragalus. In some aplacentals it is connected with the upper edge of the os calcis, as well as with the astragalus. In Birds it is articulated with the outer condyle of the femur, as well as with the tibia; but quickly tapers, and disappears at the middle of the leg. In Reptiles it forms a more important constituent of the leg, being of comparatively large size; and, in addition to being united with the tibia, it presents broad surfaces for articulation both with the femur and with the os calcis (PI. III. fig. 4)1 * * *. The greater similarity between the mode of construction of the fore and the hind limbs in these animals, as compared with the higher vertebrates, which is thus evinced in the middle segments, is also carried out, as we have just seen, in the disposition of the tarsal and the carpal bones ; it has relation to the greater similarity of function of the limbs of Reptiles as compared with the limbs of the higher animals. The fibula is on the whole a less important bone in its segment than is the ulna. We, accordingly, find that in the mammalian series it disappears more suddenly and more com- pletely than is the case with its homologue in the fore limb. Thus in the Elephant (PI. II. fig. 7), the Hippopotamus (fig. 8), and the Rhinoceros (fig. 9), though present in its whole length, it is relatively very much smaller than the ulna, and in Ruminants (fig. 10) and Solidungules (fig. 11) it is quite absent; whereas in the latter the upper articular portion of the ulna is of large size, and in the Pachyderms the ulna is continued down to the carpus. Moreover, in the fore limb, the great extensor tendon is attached to the ulna; and its bone—“ the elbow-pan ”—is commonly conjoined with the olecranon, though in some birds it is separate from it; whereas, in the hinder limb, the extensor tendon is connected with the tibia; and its bone—“ the knee-pan”—usually remains separate. In some of the Aplacentals, it is true, the fibula is prolonged above the knee-joint ; but this is on the outer side not on the fore part of the condyles of the femur. Moreover it is not commonly articulated with the condyles, being separated from them by an interval; and its unusual development in these animals is for the purpose of giving power, not to the extensor muscles of the leg, but to the muscles that effect the movements of the foot and that rotation of the foot and the tibia which, in some of these animals, takes place upon the fibula. PROXIMAL SEGMENT OF THE HIND LIMB. The single bone of the proximal segment resembles the humerus in its general features; and its great proportionate size, in relation to the other segments of the limb, and to the rest of the skeleton, constitutes, even more markedly than in the case of the humerus, one of the characteristic features of the human frame8. 1 In the Frog the tibia and fibula, like their homologues in the fore limb, are united into one bone. In the Bat a slender fibula ascends from the outer malleolus and terminates about the middle of the leg. 2 See “the Proportions of the Human Figure,” in my Treatise on the Skeleton, p. 60. Still in some Carnivora, in Sloths, Pachyderms, and Reptiles it is as long, or longer, than the tibia.