CHAP. IV.] 



THE SKELETON. 



45 



lower, which lessens the distance through which the child has 

 to be propelled; and lastly, in the bones being thinner and 

 smoother. 



The diameters of an average female pelvis given by King 

 are : 



Antero-posterior diameter of brim or inlet .... 4 inches. 



Transverse diameter of brim or inlet 4 inches. 



Oblique diameter of brim or inlet 4J to 5 inches. 



Antero-posterior of outlet 4J to 5 inches. 



Transverse of outlet 4 inches. 



Oblique of outlet 4 inches. 



The thoracic cavity. The thorax or chest is an elongated, 

 conical-shaped cage, formed by the sternum and costal cartilages 

 in front, the twelve ribs on each side, and the bodies of the 

 twelve dorsal vertebrse behind. It contains and protects the 

 principal organs of respiration and circulation. 



TABLE OF THE BONES. 



HEAD. 



Os hyoides. 



7 cervical. 

 12 dorsal. 

 Vertebrse - 5 lumbar. 



5 sacral, or sacrum. 



4 coccygeal. or coccyx. 

 Ribs. 

 Sternum. 

 Ossa innominata. 



TRUNK. 



