168 



STUDIES IN PHYSIOLOGY 



each two vertebrae. For this reason the perforations are 

 called in-ter-ver'te-bral fo-ram'i-na (Latin inter = between -|- 

 vertebrce = vertebrae -{-foramina = holes). 



One would search far before finding a more perfect means 

 of securing strength, elasticity, and flexibility than that pro- 

 vided in the structure of the human spinal column. 



The Ribs and Sternum . Attached to the transverse pro- 

 cesses of each of the twelve dorsal vertebrae, is a pair of 



slender, curved 

 bones called the 

 ribs. The first 

 seven pairs bend 

 around the sides 

 of the chest cav- 

 ity and are at- 

 tached by means 

 of cartilage to the 

 dagger-shaped 

 breastbone or 

 ster'num. The 

 cartilages of the 

 eighth, ninth, 

 and tenth pairs 

 are joined on 

 each side into 

 one, and this is 

 attached to the 

 cartilage of the 

 seventh pair. 

 The eleventh and 

 twelfth pairs are 

 called floating ribs because they have no connection with the 

 breastbone (see Fig. 68). The ends of these ribs can easily 

 be felt through the body wall on either side of the trunk. 



The Pectoral Girdle. We began our study of the skeleton 

 by a consideration of the bones of the arm. We are now to 



FIG. 69. Attachment of Ribs. 



6 = body of dorsal vertebra. 



c = cartilage connecting rib to breastbone 



r=rib. 



st = sternum or breastbone. 



tr = transverse process of vertebra. 



