2Q2 



APPLIED ANATOMY. 



from the olecranon process to the humerus, and with the periosteum may be lifted 

 up but not ruptured. This is especially the case with the periosteum above the 

 external condyle, as shown by Stimson. 



The amount of tearing of the muscles depends on the amount of displacement. 

 The flexor muscles may be partly torn from the internal condyle or the extensors 

 from the external. The brachialis anticus probably will be somewhat torn near its 

 insertion in front of the coronoid process. The biceps is not torn but may in some 

 cases be caught behind the external condyle. The orbicular ligament remains intact 

 and holds the radius in its proper relation to the ulna. 



Signs. The position assumed by the bones is usually one of slight flexion, 

 approximately 120 degrees (Hamilton). 



Viewing the elbow from the side, the anterior portion of the arm above the crease 

 is fuller than is normally the case. Posteriorly the olecranon is seen projecting, and 

 above it is a distinct hollow. On the outer side of the joint immediately in front of 

 the olecranon is seen a prominent projection caused by the head of the radius. It is 



Internal condyle of humerus 



Prominence formed by the trochlea of the 

 lower end of the humerus 



Olecranon 

 FIG. 304. Posterior luxation of the elbow; surface view of the inner side. 



to be recognized by placing the thumb on it and rotating the hand. Almost directly 

 above it may be felt, though it is not at all distinct, the external condyle (Figs. 303 

 and 305 ) . On the inner side are seen two rounded bony eminences. The posterior and 

 upper of these is the larger; it is the internal condyle. Below and anterior to this is 

 another; it is the inner edge of the trochlear articulating surface (Figs. 304 and 306). 



Measurements from the condyle to the acromion process show that they are the 

 same on the injured and the healthy sides. Measurements from the condyle to the 

 styloid process of the ulna show shortening on the injured side. As the lateral liga- 

 ments are torn there is abnormal lateral mobility. If the forearm is placed at right 

 angles to the arm, it is seen that the tip of the olecranon no longer lies on a plane 

 drawn through the long axis of the arm and the two condyles, but is considerably 

 posterior to it. 



The diagnosis as pointed out by Stimson should be based on the positive recog- 

 nition of the position of the olecranon, the two condyles, and the head of the radius. 



Treatment. 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 



