466 LIGAMENTS OF THE CHEST. 



These cartilages are the longest in the body ; they are, 

 in middle life, white, flexible, and extremely elastic. In old 

 age they are much disposed to ossify, the costal being 

 more subject to this change than the sternal end. When 

 this occurs they become opaque, and assume a similar or- 

 ganization with the ribs. The costal cartilages contain no 

 vessels or nerves, but are covered by a vascular, fibrous 

 membrane, called the perichondrium. 



LIGAMENTS OP THE CHEST. 



The ribs are articulated behind to the vertebrae, and in 

 front to the sternum. 



The vertebral articulation takes place at two points of 

 the posterior extremity of the rib, viz: at its head, and at 

 the neck and transverse process. 



The head has the capsular and the inter-articular liga- 

 ment, and two synovial membranes. 



The capsular, anterior, stellate, or radiating ligament (Fig. 

 132) arises from the front margin of the head of the rib, 

 and radiates by three short bands of ligamentous fibres, the 

 superior of which to the vertebra above the middle to the 

 intervertebral substance, and the inferior to the vertebra 

 below. These bands are so connected as to form an imperfect 

 capsule, hence one of the names of this ligament, capsular. 



The intervertebral ligament is attached to the ridge divi- 

 ding the articular surfaces on the head of the rib, and goes 

 to be inserted into the intervertebral substance. This lig- 

 ament is short, strong, and somewhat yellow, and also 

 separates the two synovial membranes which belong to the 

 head of each rib, except the first, eleventh, and twelfth. 



Internal or anterior cos to-trans verse ligament, (Fig. 140.) 

 This ligament arises narrow from the lower margin of the 

 transverse process, and has a broad insertion upon the crest 

 of the upper edge of the neck of the rib below. 



External costo-transverse or posterior ligament, (Fig. 140,) 

 arises from the extremity of the transverse process, and pro- 

 ceeds externally to be inserted into the non-articular portion 

 of the tubercle of the rib. It is a short, flat plane of fibres. 



