346 DISSECTION OF THE THORAX. 



A separate band of fibres joins the cartilage of the seventh rib to the 

 xiphoid cartilage, and is named costo-xiphoid ligament. 



Costal cartilage with the rib. The bony part of the rib is hollowed to 

 receive the costal cartilage, and the posterium of the rib is the investing 

 membrane between the two. 



COSTAL CARTILAGES TO ONE ANOTHER. The contiguous surfaces of 

 the costal cartilages from the sixth to the ninth are flattened, and are con- 

 nected by ligamentous fibres; each articulation is provided with a synovial 

 membrane. 



Movement. There is only a limited gliding motion in the chondro- 

 sternal and the interchondral articulations. The second rib-cartilage joint 

 is the most movable. 



ASTERXAL CARTILAGES. The cartilages of the three first false ribs 

 are united only by end-bands of fibrous tissue, and are freer to move than 

 those which are attached to the sternum. The lowest two, which are 

 separate from one another, are the least fixed of all. 



ARTICULATION OF THE STERNUM (fig. 51). As the two pieces of the 

 bone are united by cartilage without any synovial membrane, the kind of 

 articulation is sometimes named synchondrosis. The articulation is 

 strengthened by anterior and posterior longitudinal fibres. 



Movement. In articulations through the medium of cartilage, as here 

 and in the pelvis, there is very little motion to be perceived, even when 

 the osseous pieces are forcibly pulled by the hands. 



ARTICULATION OF THE VERTEBRAE. The vertebrae of the spinal col- 

 umn are united together by two sets of ligaments one for the bodies, and 

 the other for the arch and processes. 



Along the spinal column the ligaments have a general resemblance, and 

 one description will suffice except for those between the first two vertebrae 

 and the head, and in the pelvis. 



Dissection. After the articulations of the ribs have been examined, 

 the same piece of the spinal column will serve for the preparation of the 

 ligaments of the bodies of the vertebrae. The anterior ligament of the 

 bodies will be defined with very little trouble, by removing the areolar 

 tissue. 



It is supposed that the spinal canal has been opened to examine the 

 spinal cord, and that the posterior ligament of the bodies of the vertebrae 

 is laid bare ; but if the canal should not be open, the neural arches of the 

 vertebrae are to be removed by sawing through the pedicles. 



The remaining ligaments between the neural arches, spines, and articular 

 processes of the bones, may be dissected on the piece taken away in open- 

 ing the spinal canal. 



LIGAMENTS OF THE BODIES. The bodies of the vertebras are united by 

 an anterior and a posterior common ligament, with an intervening piece of 

 fibro-cartilage. 



The anterior common ligament (fig. 109, a) reaches from the atlas to 

 the sacrum : it is widest opposite the lumbar vertebrae, and is narrowed 

 upwards. It consists of a central wide and thick part (a), and of a thinner 

 portion (5), on each side of the body of the vertebrae. If the central piece 

 be cut across at intervals it will be seen to be thickest opposite the hollow 

 of the bodies. 



The fibres of the middle part are longitudinal in direction. By detach- 

 ing parts of the ligament, the superficial fibres will be seen to reach three 

 or more vertebrae, whilst the deep extend from bone to bone. A greater 



