TIIK SKKI.I h >N 



4' 



cl 



\ciiebra. In tin ( ase of most of them also each rib just touches 



the hotly of tlu- vi-rtcbra above that to which it belongs. These 



joints allow movement up and down. As the ribs leave the 



\ciu-ln.il column and sweep round to form the wall of the 



thorax, they slope a little downwards. The first ten ribs an 



connected to the sternum. The last portion of each 



before it meets the sternum, consists of 



cartilage, not bone. These are called 



the costal cartilages. The first seven 



ribs join the sternum separately, but the 



cartilages of the next three are connected 



liiM to each other, and then to that of the 



seventh rib ; so that they join the sternum 



indirectly only. The last two ribs, the 



eleventh and twelfth, are short and do 



not reach the sternum. They are called 



floating ribs (see Fig. 4, page 23). 



The sternum is a flat bone rather 

 more than six inches long, and two and 

 a half inches broad above, but narrow 

 below. It is something like a dagger in 

 shape. The cartilages of the first seven 

 ribs meet it on each side, but it projects 

 a considerable way beyond the place 

 where the seventh rib meets it. The 

 collar bone on each side is attached to it 

 above. 



The Pelvic Girdle. The pelvic 

 girdle, to which the thigh bones articu- 

 late, is a stron- arch springing from the 

 sacrum. It is formed by a large irregular i, , . . . 7, place 

 bone, the hip bone, on each side, which 

 arches round the lower part of the 

 abdomen, and meets its fellow in the 

 middle line in front. Each hip bone is 



firmly attached to the side of the sacrum, so that the sacrum 

 is wedged in between the two hip bones, like the keystone of 

 an arch. Ka< h hip bone has a large flat surface, which forms 

 put of the \\all of the lower part of the abdomen at the sides, 

 and gives attachment to the large muscles of the buttock. 



Kic;. 14. Sternum viewed 

 from in fmtit. 



I attach- 

 :ven rib.-.; 

 cl, places of attacliment of 

 clavicle;. ; jr, lower project 

 ing end of sternum. 



