248 ARTICULATION OF THE ELBOW. 



gin or edge of the glenoid cavity, as formed by the tendon of 

 the biceps, and is inserted into the os humeri at a small distance 

 from the edge of the cartilaginous articulating surface ; and, if 

 dissected away from the bones, would appear like a cylindrical 

 bag with both extremities open. The capsular ligament is 

 thickened in front by a band of fibres, arising from the outer part 

 of the back surface of the coracoid process, which proceeds 

 beneath the triangular ligament to the upper part of the os 

 humeri ; it is closely blended with, and forms a part of the cap- 

 sular ligament, and is denominated tbe coraco-humeral ligament, 

 or ligamentum adscititium. 



The long tendon of the biceps muscle, in the groove at the 

 head of the os humeri, appears to penetrate this ligament ; but 

 it is not within the cavity of the synovial membrane ; for this 

 membrane sends down a process like the finger of a glove, 

 which lines the groove, and is reflected from its surface upon 

 the surface of the tendon, and covers it during its whole extent, 

 being reflected from the tendon, at its upper termination, to the 

 adjoining surface ; so that the tendon is in fact outside of the 

 synovial capsule, which, therefore, confines the synovia com- 

 pletely. 



This capsular ligament, which is one of the strongest, would 

 not avail much in keeping the bones in their proper situations, 

 if the muscles and their tendons were not disposed in such a 

 manner, that when the muscles act, their power is excited to 

 the same effect. In some cases of paralytic affection, where 

 the muscles exert no influence, the weight of the arm, when it 

 is allowed to hang without support, draws the head of the os 

 humeri, below the glenoid cavity, notwithstanding the capsu- 

 lar ligament. At tfce same time it ought to be observed, that 

 this ligament must be lacerated in every case of complete 

 luxation of the os humeri ; as it cannot possibly distend suffi- 

 ciently to permit the separation of the bones to the extent which 

 then takes place. 



The Articulation of the Elbow. 



Those surfaces of the os humeri, ulna, and radius, which move 

 upon each other, are covered with cartilage. 



