334 THE ARTICULATIONS 



Anterior Chondro-sternal. Interarticular Chondro-sternal. 



Posterior Chondro-sternal. Anterior Chondro-xiphoid. 



Capsular. Posterior Chondro-xiphoid. 



The Anterior Chondro-sternal Ligament is a broad and thin membranous band 

 that radiates from the front of the inner extremity of the cartilages of the true 

 ribs to the anterior surface of the sternum. It is composed of fasciculi which pass 

 in different directions. The superior fasciculi ascend obliquely, the inferior pass 

 obliquely downward, and the middle fasciculi horizontally. The superficial fibres 

 of this ligament are the longest : they intermingle with the fibres of the ligaments 

 above and below them, with those of the opposite side, and with the tendinous 

 fibres of origin of the Pectoralis major, forming a thick fibrous membrane which 

 covers the surface of the sternum. This is more distinct at the lower than at the 

 upper part. 



The Posterior Chondro-sternal Ligament, less thick and distinct than the 

 anterior, is composed of fibres which radiate from the posterior surface of the 

 sternal end of the cartilages of the true ribs to the posterior surface of the sternum, 

 becoming blended with the periosteum. 



The Capsular Ligament surrounds the joints formed between the cartilages 

 of the true ribs and the sternum. It is very thin, intimately blended with the 

 anterior and posterior ligaments, and strengthened at the upper and lower part of 

 the articulation by a few fibres which pass from the cartilage to the side of the 

 sternum. These ligaments protect the synovial membranes. 



The Interarticular Chondro-sternal Ligaments. These are only found between 

 the second and third costal cartilages and the sternum. The cartilage of the 

 second rib is connected with the sternum by means of an interarticular ligament 

 attached by one extremity to the cartilage of the second rib, and by the other 

 extremity to the cartilage which unites the first and second pieces of the sternum. 

 This articulation is provided with two synovial membranes. The cartilage of the 

 third rib is connected with the sternum by means of an interarticular ligament 

 which is attached by one extremity to the cartilage of the third rib, and by the 

 other extremity to the point of junction of the second and third pieces of the 

 sternum. This articulation is provided with two synovial membranes. 



The Anterior Chondro-xiphoid. This is a band of ligamentous fibres which 

 connects the anterior surface of the seventh costal cartilage, and occasionally also 

 that of the sixth, to the anterior surface of the ensiform appendix. It varies in 

 length and breadth in different subjects. 



The Posterior Chondro-xiphoid is a similar band of fibres on the internal or 

 posterior surface, though less thick and distinct. 



Synovial Membranes. There is no synovial membrane between the first costal 

 cartilage and the sternum, as this cartilage is directly continuous with the sternum. 

 There are two synovial membranes, both in the articulation of the second and third 

 costal cartilages to the sternum. There is generally one synovial membrane in each 

 of the joints between the fourth, fifth, sixth, and seventh costal cartilages to the 

 sternum; but it is sometimes absent in the sixth and seventh chondro-sternal 

 joints. Thus there are eight synovial cavities on each side in the articulations 

 between the costal cartilages of the true ribs and the sternum. After middle life 

 the articular surfaces lose their polish, become roughened, and the synovial 

 membranes appear to be wanting. In old age the articulations do not exist, the 

 cartilages of most of the ribs becoming continuous with the sternum. 



Actions. The movements which are permitted in the chondro-sternal articu- 

 lations are limited to elevation and depression, and these only to a slight extent. 



Articulations of the Cartilages of the Ribs with each other 

 (Interchondral) (Fig. 238). 



The contiguous borders of the sixth, seventh, and eighth, and sometimes the 

 ninth and tenth, costal cartilages articulate with each other by small, smooth, 



