DISSECTION OF THE ANTERIOR LIMB. 45 



synovial membrane, and the articular surfaces of the bones covered by 

 articular cartilage. 



The Synovial Membrane lines the inner surface of the capsular 

 ligament. It secretes the synovia, or joint oil, some of which will be 

 seen escaping from the joint. 



THE ELBOW-JOINT (PLATE 11, FIG. 1). 



This joint is formed by the lower extremity of the humerus and the 

 upper extremities of the bones of the fore-arm. It possesses two lateral 

 ligaments, and an anterior ligament which supports the synovial mem- 

 brane in front ; but behind, there being no ligament, the synovial sac is 

 directly supported by muscles. 



Movements. — This is a ginglymoid joint, the only movements being 

 flexion and extension. In flexion, while the humerus remains fixed, the 

 bones of the fore-arm are carried forwards until the movement is 

 arrested by the coronoid process passing into the fossa of the same 

 name. In this movement the bones of the fore-arm do not move in 

 the plane in which the humerus lies, but deviate a little outwards. 

 The opposite movement is extension, in which the radius and ulna are 

 carried backwards until they are arrested by the tension of the lateral 

 ligaments, and by the passage of the beak of the olecranon into the 

 fossa of the same name. 



Directions. — The anterior and lateral ligaments are to be exposed 

 and defined by removing the muscles from the front of the joint, but on 

 the posterior aspect of the joint the muscles should not be removed at 

 present. 



The External Lateral Ligament is a cord-like band which is fixed 

 superiorly to a depression on the outer side of the lower extremity of 

 the humerus, and to the ridge which forms the lower boundary of the 

 musculo-spiral groove ; while inferiorly it passes to be inserted into the 

 external tuberosity at the upper end of the radius. 



The Internal Lateral Ligament forms a longer but more slender 

 cord than the preceding, and passes from a small eminence on the 

 outer side of the lower extremity of the humerus to be inserted into the 

 shaft of the radius below the bicipital tuberosity. Some of the anterior 

 fibres join the tendon of the biceps or the anterior ligament, while some 

 of the posterior join the arciform fibres connecting the radius and 



ulna. 



The Anterior Ligament is of a membranous form. Its upper border 

 is fixed to the humerus, and its lower border to the radius, while its 

 lateral borders blend with the lateral ligaments. 



Directions.— 'il^e anterior and lateral ligaments should now be cut 

 transversely about their middle in order to expose the interior of the 

 joint. 



