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Show rosmon or THE HUMERUS WHEN DrsL'ocsirED. DISLOUATION UF 'lHIl BUMERUS. 175 D /‘-‘\‘ \ -. J\ .-,...-«~. A,--~ - . a, ._ .,,A ram. : . ‘ W" J/// In this sketch the scapula and humerus are represented in the relation to each other as if the humerus was just slipping from its position. Here it is evident, that as the line C, from the upper margin of the scapula t0 the nearest point of the attachment of the capsule to the humerus is shorter than the line D, which encircles the head of the bone, so will the side (4-6"? -Wam.‘-ws-Mu a». _, ‘ . s3, of the capsule which answers to C, be less stretched than the ion or part at D, during; dislocation. Indeed the upper part of the capsule of the joint is not more stretched when the lite merns has slipped from the articulating surface of the scapula, than when the arm hangs naturally by the side. If in the dead body we cut the lower part of the capsule of the joint the humerus is easily dislocated, but if we cut the upper part only, and let the lower part 0! the capsule remain entire, it is very diliicult to disloeate the bones, and not without tearing the lower part of the capsule. In truth, when the humerus is dislocated this is the state of the bones and ligament. A, the scapula. B, the humerus dislocated. C, the capsule still entire on the upper part, though completely torn away on the lower and fore part. D, the rough protuberance of the head of the humerus checked under the neck of the scapula. And now it is evident, that when the arm is brought to the direction of the line E, the capsule C, resists the depression of the bone, and throws up the point D, under the neck of the scapula, and the greater the force employed to stretch the arm the firmer are the humerus and scapula tied together at the points C D. But if on the contrary we desist from this direction of the force horizontally, and raise the arm into the direction of the line G H, then the capsule C, is relaxed, and the point D, escapes from under the neck of the scapula and the bone is reduced. In conclusion then, though by placing the fore arm in the axilla of the patient, and raising the head of the humerus while we depress the elbow, we facilitate the reduction when no part of the capsule remains, yet if there remains any shred of the capsule this manoeuvre will directly impede the reduc~ tion. \Ve must on the contrary elevate the elbow, or let the body of the patient fall somewhat more laterally, in order to i'u‘llitate the reduction. :1 "Won mm Moss |
