The hand : its mechanism and vital endowments, as evincing design / by Charles Bell.

  • Bell, Charles, Sir, 1774-1842.
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: The hand : its mechanism and vital endowments, as evincing design / by Charles Bell. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    more certainly when he is pitched on his shoulder, the collar- bone is broken; because in man, this bone forms the link of connexion between the shoulder and the trunk, and it accord- ingly receives the whole shock. Now the same would happen in the horse, the stag, and all quadrupeds of great strength and swiftness, were not the scapulas sustained by muscles, in place of bone, and did not the bones recoil and fold up. The horse-jockey runs his hand down the horse's neck, in a knowing way, and says, This horse has got a heavy shoulder; he is a slow horse! He may be right, and yet not understand the matter. It is not possible that the shoulder can be too much loaded with muscle, for muscle is the source of motion, and be- stows power. What the jockey feels, and forms his judgment on, is the abrupt transition from the neck to the shoulder; while, in a horse for the turf, there ought to be a smooth undulating surface. This abruptness, or prominence of the shoulder, is a consequence of the upright position of the scapula; the slop- ing and light shoulder results from its obliquity. An upright shoulder is therefore the mark of a stumbling horse : the scapula does not revolve easily, to throw forward the foot. Much of the strength, if not the freedom and rapidity of motion of a limb, will depend on the angle at which the bones lie to each other; for that mainly affects the insertion, and, con- sequently, the power of the muscles. We know, and may every moment feel, that when the arm is extended, we possess little power in bending it; but in proportion as we bend it, the power is increased. This is owing to the change in the direction of the muscular force acting upon the bone ; or, in other words, to the tendon of the muscle becoming more perpendicular to the lever. A scapula which inclines obliquely backwards, increases the angle at which the humerus, or arm-bone, lies with reference to it: and, consequently, the muscles which pass from it to the arm- bone, will act with greater effect, from being inserted into that bone more nearly at a right angle. We have only to turn to the skeleton of the elephant, the ox, the elk, or the stag, to see the confirmation of this principle. When the scapula lies obliquely on the chest, the serratus muscle, which passes from the ribs to its uppermost part, has more power in rolling it. This direction of the scapula causes it to lie at right angles with the humerus; and, accordingly, the muscles which are attached to the latter