25. A fall on the point of the shoulder is the most frequent cause of
this luxation. The two articulating surfaces, representing an inclined
plain, slide along each other, in such a manner, that that which
belongs to the acromion is pushed inward, while that of the clavicle
is directed outward. The capsule being stretched, gives way, and then
the displacement is manifested by a preternatural protuberance over
the acromion; by a stiffness in the motion of the shoulder; by the
direction of this part, which is evidently drawn inward and downward;
by the inclination of the head of the patient to the side affected;
by a bending of the body; and by severe pains in the luxated part.
These characters are essentially distinct, and ought to have prevented
the error of Galen, who mistook a case of this kind for a luxation
of the os humeri downward. Hippocrates and Ambrose Pare have foreseen
the possibility of this mistake and even warned young practitioners to
be on their guard against it. But, as citizen Sabattier judiciously
observes, the position of the head of the humerus, under the arm, in
a luxation of that bone, will remove all uncertainty respecting the
nature of the injury.
§ VII.