A comparison of the shoulder bones and muscles with the pelvic bones and muscles / by Professor Humphry.

  • George Murray Humphry
Date:
[1870?]
Catalogue details

Licence: Public Domain Mark

Credit: A comparison of the shoulder bones and muscles with the pelvic bones and muscles / by Professor Humphry. Source: Wellcome Collection.

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    hinder border, and that the rectus extends from the anterior border of the ilium upon its outer surface above the acetabulum. The origin therefore of the two may be traced to corresponding points upon the external or dorsal aspects of their respective bones; and the one has been turned backwards upon the hinder border of the scapula, while the other has been turned forwards upon the anterior border of the ilium, in consequence of the rotation of the extensor surfaces of the limbs in those directions b This difficulty becomes therefore an argument in favour of the view that the rotation of the parts of the limbs that are free from the body is not accompanied by a corresponding rotation of the parts lying in the visceral wall. An important difference between the two limbs in mammals, which has a material effect upon the inferior components of the girdles, is to be found in the position of the limbs, or rather of the proximal components of the limbs, with regard to the respective girdles. The hind limb impinges upon the pelvis laterally. The direction of forces from it to the pelvis is con¬ sequently Awards as well as upwards; and this is associated, as a general rule, with the completion of the bony arch beneath which is effected by means of the great development of the ischium and os pubis, and the meeting of the pubic and perhaps the ischiatic bones of the two sides at the symphysis. The fore-limb including the humerus in mammals, excepting mono- tremes, is placed beneath, that is, in a line with the scapula, and the forces are consequently directed from it to the scapula more vertically than in the case of the hind-limb. The lower elements of the girdle are accordingly comparatively abortive, and do not approach the middle line. In monotremes, however, as well in the inferior classes, the fore-limbs are more sprawl¬ ing, the humerus runs out almost horizontally from the trunk, the glenoid cavity is more lateralized and the direction of forces from the limb is more mwards. Hence the lower elements of the girdle acquire a development more or less corresponding with those of the pelvis, and abut upon one another or upon the sternum. Another, but less important difference, to some extent 1 In Manis the triceps arises from the whole length of the spine of the sca¬ pula, as well as from the hinder border. Journal of Anat. iv. 38.
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