This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The lower end of the humerus rests in front of the coronoid process (rarely fractured). When the forearm is flexed the triceps becomes tense and holds the bones locked in their displaced position. The coronoid process prevents the humerus from going back into place. To reduce the dislocation, the triceps is to be relaxed by extending the forearm to an angle of about 120 degrees, thus lowering the coronoid process, and extension is to be made on the forearm and counterexten-sion on the arm. Usually an anaesthetic is not required (Fig. 307).
Fig. 305. - Posterior luxation of the elbow, showing the position of the bones as viewed from the outer side.
Fig. 306. - Posterior luxation of the elbow, showing the position of the bones as viewed from the inner side.
In inward dislocation the ulna and radius are pushed toward the inner side. 1 he head of the radius leaves the capi-tellum to rest on the adjacent portion of the trochlea. The olecranon slides from the outer to the inner surface of the trochlea. The outer condyle then becomes prominent while the inner becomes confused with the olecranon. The identity of the condyles is always to be established by tracing them up the humerus. This dislocation is always incomplete.
Fig. 307. - Dissected preparation of posterior luxation of the elbow, viewed from the inner side.
Extension and counterextension with the arm slightly flexed to release the coronoid process aided by direct pressure on the humerus inward and the ulna outward.
In outward dislocation the concave surface of the olecranon rests on the capitellum and in the groove between it and the trochlea. The head of the radius projects far to the outer side of the external condyle. The inner condyle and trochlea become quite prominent and can be readily recognized.
Slight flexure of the forearm. Traction and pressure on the radius inward and on the internal condyle and lower end of the humerus outward.