300 



SYNDESMOLOGY 



ment does not exist; but the fibers of the ligament in each case are connected to 

 the vertebra above, as well as to that with which the rib articulates. 



The Interarticular Ligament (ligamentum capituli cosies, interarticulare) . The in- 

 terarticular ligament is situated in the interior of the joint. It consists of a short 

 band of fibers, flattened from above downward, attached by one extremity to the 

 crest separating the two articular facets on the head of the rib, and by the other 

 to the intervertebral fibrocartilage; it divides the joint into two cavities. In the 

 joints of the first, tenth, eleventh, and twelfth ribs, the interarticular ligament does 

 not exist; consequently, there is but one cavity in each of these articulations. 

 This ligament is the homologue of the ligamentum conjugate present in some 

 mammals, and uniting the heads of opposite ribs, across the back of the inter- 

 vertebral fibrocartilage. 



Anterior 



costotransverse 



ligaments 





Interarticular ligament 



Intervertebral fibrocartilage 



FIG. 312. Costovertebral articulations. Anterior view. 



Synovial Membranes. There are two synovial membranes in each of the articulations where 

 an interarticular ligament exists, one above and one below this structure; but only one in those 

 joints where there are single cavities. 



2. Costotransverse Articulations (articulationes costotransversarice) (Fig. 313). 

 The articular portion of the tubercle of the rib forms with the articular surface 

 on the adjacent transverse process an arthrodial joint. 



In the eleventh and twelfth ribs this articulation is wanting. 

 The ligaments of the joint are : 



The Articular Capsule. The Posterior Costotransverse. 



The Anterior Costotransverse. The Ligament of the Neck of the Rib. 



The Ligament of the Tubercle of the Rib. 



