256 



ARTICULATION OF THE RIBS. 



I 



Fig. 61.* — The capsular ligament of 



the costo-vertebral articulation, 

 is not complete. It is much 

 thickest in front and upon the 

 sides, and radiates from its origin 

 on the head of the ribs, whence 

 it is usually called the anterior 

 f^it!^?*'*^^ '''(^diating or stellate ligament. 

 ^'^ — There is also a small inter- 



articulating ligament, in this 

 articulation, which passes from a ridge on the head of the rib to 

 a corresponding line on the intervertebral substance. It thus 

 divides the joint into two halves, each of which has a separate 

 synovial membrane. This ligament does not exist where the 

 ribs are attached to a single vertebra, as the first, eleventh and 

 twelfth. 



— The costo-transverse articulation, besides its feeble capsular 

 ligament and synovial membrane connecting the tubercle of the 

 rib with the facet of the transverse process, includes three other 

 ligaments, the internal transverse, the external transverse, and 

 the middle costo-transverse. 



— The internal transverse, arises from the inferior margin of the 

 transverse process, and is inserted into the upper margin of the 

 neck of the rib below. 



— The external transverse, arises from the extremity of the 

 transverse process, and is inserted into the corresponding rib, just 

 beyond the tubercle. 



— The middle costo-transverse ligament is extended between the 

 neck of the rib and the contiguous transverse process. To be 

 well seen it is necessary to saw longitudinally through the neck 

 of the rib and its transverse process. 



These ligaments permit the motions necessary for respiration, 

 and restrain all others. 



* The anterior ligaments of the vertebraR, and ligaments of the ribs. 1. The 

 anterior common ligament. 2. The anterior costo-vertebral or stellate ligament. 

 3. The anterior costo-transverse ligament. 4. The inler-articnlar ligament con- 

 necting the head of the rib to the intervertebral substance, and separating the 

 two synovial membranes of this articulation. 



