460 THE THORAX. 



descend to be attached to the body of the axis, presenting, 

 as seen, in the figure above, a crucial appearance. The use 

 of this ligament is to retain the odontoid process and the 

 atlas in secure connection with each other. 



The anterior atlanto-axoid ligament extends from the ante- 

 rior tubercle and arch of the atlas to the base of the odon- 

 toid process, and is continuous with the anterior vertebral 

 ligament. It is strong and thick. 



The posterior atlanto-axoid is situated between the pos- 

 terior arch of the atlas, and the lamina of the axis ; it 

 corresponds to the ligamenta sub-flava, is a thin, broad, and 

 weak membrane, but not elastic. 



The capsular ligaments are two in number, one on each 

 side, and belong to the oblique processes of the atlas and 

 axis. They surround the margins of these processes, and 

 are loose enough to allow freedom of motion. They are, 

 like all the oblique articulations, lined with synovial mem- 

 brane, which occasionally communicates with the syno- 

 vial membrane of the transverse ligaments and odontoid 

 process. 



The ligaments of the false vertebree the sacrum and 

 coccyx, will be noticed along with those of the pelvis. 



SECTION II. 

 THE THORAX OR CHEST. 



The chest forms the upper part of the trunk, and is com- 

 posed of the sternum and costal cartilages in front the ribs 

 laterally, and the dorsal vertebrae, which have already 

 been considered, behind. Its form is conoidal, flattened in 

 front, rather concave behind, and convex upon the sides. 

 Its summit or superior portion is smaller than the inferior 

 or base, and presents a very oblique opening ; cordiform in 

 its shape, and much lower in front than behind. The base 

 is a large foramen, bounded by the lateral and posterior 

 margins of the lower ribs and their cartilages, marking the 

 situation of the diaphragm. 



The sternum (attpvov, the breast) is situated on the me- 



' : 



