The second occurs when a violent blow is received on the elbow, or, more particularly, from falls on that part: for example, if, when descending a flight of stairs, our heel slip and we fall backwards, the arm is suddenly thrown behind to save the body. In such a case, the olecranon striking forcibly against one of the steps, and being pressed between it and the weight of the body, is broken. In this way was the disease produced in a majority of the patients attended by Desault for fractures of the olecranon. § XIV. OF THE SIGNS. 43. We meet here with the same appearances and state of things, which constantly occur in fractures of the rotula. The triceps extensor, finding no longer in the continuity or sound state of the ulna, a resistance to its contractions, draws upwards the short fragment to which it adheres, produces between it and the lower one an interval more or less perceptible, and gives rise to the greater part of the other characteristic signs of the affection: these are, 1st, An interval or space between the fragments, corresponding to the posterior part of the articulation. This interval may be increased at pleasure, by increasing the flexion of the fore-arm, or by making the patient contract the triceps muscle, and may be again diminished, by bringing the arm into a state of extension: 2dly, An inability in the patient to extend the fore-arm spontaneously, which is the necessary result of the separation of the triceps from the ulna: 3dly, A constant semiflexion or half-bent state of the fore-arm, produced by the contractions of the biceps and brachialis internus muscles, to which no antagonists are now opposed: 4thly, An elevation, more or less perceptible, of the olecranon above the condyls, which, on the contrary, rise above it, when, in a natural state of the parts, the fore-arm is half-bent: 5thly, A facility of moving the upper fragment in every direction, without communicating any motion to the ulna; 6thly, A peculiar sensation experienced by the patient, to whom it seems, when he makes an effort to extend the fore-arm, as if some body or substance were detached or broken off from his elbow, and carried upwards. The patient may realize the justness of this sign, by comparing it with what he feels on attempting to extend the opposite fore-arm, placed in the same position.