. A practical treatise on fractures and dislocations. e joint must be distinguished from that of the limb. The formercan take place even while the elbow is below the level of the shoulder, for it is deter-mined by the relations between the humerus and the scapula; and as the scapula is freelymovablethe position of the limb (with reference to the body), when the limit of motionin the joint is reached, varies with that of the scapula. ANTERIOR DISLOCATIONS OF THE SHOULDER 559 capsule in its inner ami lower portion. After this rupture has takenplace and the upward movement of the elbow has ceased
. A practical treatise on fractures and dislocations. e joint must be distinguished from that of the limb. The formercan take place even while the elbow is below the level of the shoulder, for it is deter-mined by the relations between the humerus and the scapula; and as the scapula is freelymovablethe position of the limb (with reference to the body), when the limit of motionin the joint is reached, varies with that of the scapula. ANTERIOR DISLOCATIONS OF THE SHOULDER 559 capsule in its inner ami lower portion. After this rupture has takenplace and the upward movement of the elbow has ceased, the contraction of the muscles, the deltoid, pectoralis major, and latissimus dorsi,draws the head of the humerus inward past the anterior lip of the gle-noid fossa, and then when the elbow is lowered the head rises along theinner side of the joint, for the nntorn outer and anterior portion of ihecapsule is made tense and, by thus preventing the descent of the portionof the bone to which it is attaehed, compels the movement to take place Fig. Subcoracoid dislocation on a cadaver: showing rupture of lower part of the subscapular^. (B. Anger.) about this portion as a centre. As the first new centre of motion atthe edge of the acromion determines, in connection with the muscles,the primary displacement, so the second new centre on the humerusat the outer and anterior attachment of the capsule determines thesecondary displacement and the final position of the head of the boneand the attitude of the limb. Muscular action, the contraction of the muscles of the individualhimself, can produce a dislocation either by drawing the head of thebone directly out of its socket, or, much more commonly, by creatingconditions of leverage and momentum similar to those existing in theproduction of dislocations by indirect violence. In many of the re-ported cases it is difficult to recognize the mechanism of the least questionable examples of dislocation effected by the directtra
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