THE RIBS 



139 



from its opponent, exerts its full power on the lung and 

 it collapses. 



5. The Movements of Respiration. — The hinder ends 

 of the ribs are attached to the vertebral column so as to 



Fig. 44.— The Boty "Walls of the Thor.\x. 



a, b, vertebral column ; 1-12, ribs ; c, sternum ; d costal cartilages ; 

 e, united cartilages of lower true ribs. 



be freely movable upon it. The front ends of the first 

 ten pairs of ribs are connected either directly (first seven 

 ribs), or indirectly (next three ribs), by the costal 

 cartilages to the sternum, the connection being therefore 

 flexible (Figs. 41, 44, 45). When left to themselves the ribs 

 take a position which is inclined obliquely do^Tiwards and 

 forwards. 



