66 Anatomy Applied to Medicine and Swgery. 



have seen, however, that inflammation of the bursa beneath 

 the triceps produces a similar bulging on either side of the 

 tendon, hence, to differentiate the one from the other, it 

 must be remembered, that the head of the radius is ex- 

 posed in the posterior triangular space, and, that the syno- 

 vial membrane of the joint surrounds the radial head, 

 consequently in synovitis of the elbow joint we can elicit 

 fluctuation by placing one finger over the head of the 

 radius in this triangle, and another finger over the swelling 

 on either side of the triceps tendon, but, in bursitis, fluctuation 

 can be elicited from one side of the tendon to the other 

 side only, and not to the head of the radius. 



The Elbow Joint is a ginglymus or hinge joint, 

 and depends for its strength chiefly on the interlocking 

 of the bones that enter into its formation, rather than on 

 the presence of ligaments as in the case of the sterno-clavic- 

 ular articulation, or, on the action of muscles, as in the 

 shoulder joint. The ligaments that assist in protecting 

 the joint are : The anterior, the posterior, the internal and 

 the external, and, of these, the two latter are strong and 

 closely attached to the bones that form the joint, whereas 

 the two former are lax the posterior one especially. As 

 stated above, this articulation is a ginglymus or hinge 

 joint, but it is more than a mere hinge joint since the 

 hinge refers to the articulation of the ulna with the 

 humerus only, and not to the articulation of the radius 

 with the humerus. The latter joint, i.e., the humero- 

 radial, would appear at first glance to be an enarthrodial 

 joint, since the cup-shaped depression of the head of the 

 radius articulating with the radial head of the humerus, 

 would apparently allow movement in every direction, and, 

 this it would do, were it not that the orbicular and 

 the radio-ulnar ligaments prevent separation of the bones, 

 and, therefore, interfere with circumduction of the radius. 



