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Show v "Hr- v5»..- guys-p1; . -W....,. .A i712 Ii, l t i i ACCIDENTAL REDUCTION or TIIE HUMERUS. REDUCTION IMPEDED BY THE MUSCLES. downward directly opposes it. I shall first state the fact of the great difficulty which sometimes occurs to the reduction ' of the dislocated shoulder, and then explain it from the consideration of the anatomy. We are told that cases have occurred where no effort has succeeded in reducing the humerus, until by some unintentional motion, and by accident, the head of the bone has slipt into its place. What are we to think of this ? not that the reduction is an accident, and that we are to move the arm in vari- ous directions until by a lucky chance the dislocation is reduced ! A little further enquiry teaches us that there is a certain position in which the bone resists, and one also in which it as certainly yields. I have experienced this in the living body, and produced the same eiTect in the dead body. I have found that upon pulling the arm directly out from the body, horizontally, that not the smallest progress was made ; but that at last the patient's body yielding somewhat, the etl‘ect was, that in relation to the scapula the position of the humerus was considerably raised, and that then the head of the bone slipped into its place. The explanation which has been given of this accidental reduction is, that the head of the humerus when it was dis- r.m*n:~Vwaatv~r-a« "-44 a. ‘. hg . _ placed burst through the capsular ligament without tearing it entirely away, and that the head of the bone was retained noosed in a slit of the capsule, so that it could not be reduced unless the arm was brought exactly to the position in which it was when displaced. To this it has been objected, that the head of the humerus does. not merely burst through thC capsule when dislocation takes place. ; the capsule is torn largely away from the edge of the glenoid cavity, so that the head of the bone cannot be retained in the slit of the capsule. it has been very resolutely affirmed, that the cause of this difficulty of reduction is to be found in the muscles : that the head of the bone when it burst from the capsule was pushed through betwixt the teres major and the subscnpularis in this manner. C, the head of the B, the scapula. A, the clavicle. humerus thrust betwixt the muscles. 1), the subsr'npulnris mat-1. ~."."" inf» rmd tcres minor. tissimus (lorsi. I, the biceps. E, the teres major. G, the deltoidcs. 1", is part of the la- H, the roraco-brarhiulis. This sketch was taken from a dissection after an experiment on the dead body. It proved more than is shown here, for on pressing down the arm bone to the horizontal direction I found that the reduction was prevented, and keeping the parts in the exact position. I cut away all the muscles, and still the humerus was retained checked ; but then what made the obstruction became apparent, viz. the upper part of the capsular ligament. But I must now explain in what manner The capsule is torn. W1; W0 w more |