302 SYNDESMOLOGY 



The Ligament of the Neck of the Rib (ligamentum colli costce; middle costotransverst 

 or interosseous ligament). The ligament of the neck of the rib consists of short 

 but strong fibers, connecting the rough surface on the back of the neck of the rib 

 with the anterior surface of the adjacent transverse process. A rudimentary 

 ligament may be present in the case of the eleventh and twelfth ribs. 



The Ligament of the Tubercle of the Rib (ligamentum tuberculi costce; posterior 

 costotransverse ligament). The ligament of the tubercle of the rib is a short but 

 thick and strong fasciculus, which passes obliquely from the apex of the transverse 

 process to the rough non-articular portion of the tubercle of the rib. The ligaments 

 attached to the upper ribs ascend from the transverse processes; they are shorter 

 and more oblique than those attached to the inferior ribs, which descend slightly. 



Movements. The heads of the ribs are so closely connected to the bodies of the vertebra 

 by the radiate and interarticular ligaments that only slight gliding movements of the articular 

 surfaces on one another can take place. Similarly, the strong ligaments binding the necks and 

 tubercles of the ribs to the transverse processes limit the movements of the costotransverse 

 joints to slight gliding, the nature of which is determined by the shape and direction of the articular 

 surfaces (Fig. 314). In the upper six ribs the articular surfaces on the tubercles are oval in shape 

 and convex from above downward; they fit into corresponding concavities on the anterior sur- 

 faces of the transverse processes, so that upward and downward movements of the tubercles are 

 associated with rotation of the rib neck on its long axis. In the seventh, eighth, ninth, and tenth 

 ribs the articular surfaces on the tubercles are flat, and are directed obliquely downward, medial- 

 ward, and backward. The surfaces with which they articulate are placed on the upper margins 

 of the transverse processes; when, therefore, the tubercles are drawn up they are at the same 

 time carried backward and medialward. The two joints, costocentral and costotransverse, move 

 simultaneously and in the same directions, the total effect being that the neck of the rib moves 

 as if on a single joint, of which the costocentral and costotransverse articulations form the ends. 

 In the upper six ribs the neck of the rib moves but slightly upward and downward; its chief 

 movement is one of rotation around its own long axis, rotation backward being associated with 

 depression, rotation forward with elevation. In the seventh, eighth, ninth, and tenth ribs the 

 neck of the rib moves upward, backward, and medialward, or downward, forward, and lateral- 

 ward; very slight rotation accompanies these movements. 



VI. Sternocostal Articulations (Articulationes Sternocostales ; Costosternal 



Articulations) (Fig. 315). 



The articulations of the cartilages of the true ribs with the sternum are 

 arthrodial joints, with the exception of the first, in which the cartilage is directly 

 united with the sternum, and which is, therefore, a synarthrodial articulation. 

 The ligaments connecting them are : 



The Articular Capsules. The Interarticular Sternocostal. 



The Radiate Sternocostal. The Costoxiphoid. 



The Articular Capsules (capsules articulares; capsular ligaments'). The articular 

 capsules surround the joints between the cartilages of the true ribs and the 

 sternum. They are very thin, intimately blended with the radiate Sternocostal 

 ligaments, and strengthened at the upper and lower parts of the articulations by a 

 few fibers, which connect the cartilages to the side of the sternum. 



The Radiate Sternocostal Ligaments (ligamenta sternocostalia radiata; chondro- 

 sternal or Sternocostal ligaments} . These ligaments consist of broad and thin mem- 

 branous bands that radiate from the front and back of the sternal ends of the 

 cartilages of the true ribs to the anterior and posterior surfaces of the sternum. 

 They are composed of fasciculi which pass in different directions. The superior 

 fasciculi ascend obliquely, the inferior fasciculi descend obliquely, and the middle 

 fasciculi run horizontally. The superficial fibers are the longest; they intermingle 

 with the fibers of the ligaments above and below them, with those of the opposite 

 side, and in front with the tendinous fibers of origin of the Pectoralis major, form- 



