LIGAMENTS OP THE RIBS. 



113 



Fig. 49.* 



of several fasciculi, which ascend from the crest upon the neck of 

 the rib, to the transverse process immediately above. This liga- 

 ment separates the anterior from the posterior branch of the inter- 

 costal nerves. 



The middle costo-transverse ligament is a very strong interosseous 

 ligament, passing directly between the posterior surface of the neck 

 of. the rib, and the transverse process against which it rests. 



The posterior costo-transverse ligament is a small but strong fasci- 

 culus, passing obliquely from the tubercle of the rib, to the apex of 

 the transverse process. The articulation between the tubercle of the 

 rib and the transverse process is provided with a small synovial 

 membrane. 



There is no anterior costo-transverse 

 ligament to the first rib ; and only rudi- 

 mentary posterior costo-transverse to the 

 eleventh and twelfth ribs. 



Actions. The movements permitted by 

 the articulations of the ribs, are upwards 

 and downwards, and slightly forwards and 

 baclavards; the movement increasing in 

 extent from the head to the extremity of 

 the rib. The forward and backward 

 movement is very trifling in the seven 

 superior, but greater in the inferior ribs ; 

 the eleventh and twelfth are very mo- 

 vable. 



7. Articulation of the Ribs with the Sternum, and with each other. 

 The ligaments of the costo-sternal articulations are, 



Anterior costo sternal, 

 Posterior costo-sternal, 

 Superior costo-sternal, 

 Inferior costo-sternal, 

 Synovial membranes. 



The anterior costo-sternal ligament is a thin band of ligamentous 

 fibres, that passes in a radiated direction from the extremity of the 

 costal cartilage to the anterior surface of the sternum, and inter- 

 mingles its fibres with those of the ligament of the opposite side, 

 and with the tendinous fibres of origin of the pectoralis major 

 muscle. 



The posterior costo-sternal ligament is much smaller than the an- 

 terior, and consists of only a thin fasciculus of fibres situated on the 

 posterior surface of the articulation. 



* A posterior view of a part of the thoracic portion of the vertebral column, showing 

 the ligaments connecting the vertebrae with each other and the ribs with the vertebras. 

 1. The supra-spinous ligament. 2, 2. The ligamenta subflava, connecting the laminse. 

 3. The anterior costo-transverse ligament. 4. The posterior costo-transverse liga- 

 ments. 



15 



