THE ELBOW-JOINT. 



255 



V. Elbow-joint (Figs. 171, 172). 



The Elbow is a ginglymus or hinge-joint. The bones entering into its forma- 

 tion are the trochlear of the humerus, which is received into the greater sigmoid 

 cavity of the ulna, and admits of the movements peculiar to this joint viz. 

 flexion and extension ; whilst the lesser, or radial, head of the humerus articulates 

 with the cup-shaped depression on the head of the radius ; the circumference of the 

 head of the radius articulates with the lesser sigmoid cavity of the ulna, allowing of 

 the movement of rotation of the radius on the ulna, the chief action of the supe- 

 rior radio-ulnar articulation. The articular surfaces are covered with a thin layer 

 of cartilage, and connected together by a capsular ligament of unequal thickness, 

 being especially thickened on its two sides and, to a less extent, in front and 

 behind. These thickened portions are usually described as distinct ligaments 

 under the following names: 



Anterior. 

 Posterior. 



Internal Lateral. 

 External Lateral. 



The orbicular ligament of the upper radio-ulnar articulation must also be 

 reckoned among the ligaments of the elbow. 



The Anterior Ligament (Fig. 171) is a broad and thin fibrous layer which 

 covers the anterior surface of the joint. It is attached to the front of the internal 



condyle and to the front of the 

 humerus immediately above the 

 coronoid and radial fossae ; below, 



FIG. 171. Left elbow-joint, showing anterior 

 and internal ligaments. 



FIG. 172. Left elbow-joint, showing poste- 

 rior and external ligaments. 



to the anterior surface of the coronoid process of the ulna and orbicular liga- 

 ment, being continuous on each side with the lateral ligaments. Its superficial 



