82 



OSTEOLOGY 



representing the handle, is called the manubrium; 

 the middle and larger portion, which resembles the 

 blade, is the gladiolus; and the inferior piece, which 

 resembles the point of the sword, is called the ensiform. 



The Ribs (Costse). There are twelve pairs, one on 

 each side. They are obliquely placed, running forward 

 and downward. The obliquity increases from above 

 downward to the ninth rib, when it reaches the 

 maximum; from this point downward it decreases. 



The first seven pairs, attached by costal cartilages 

 to the sternum, are called sternal, true, or vertebro- 

 sternal ribs, the remaining lower five pairs are asternal 

 or false ribs; each of the upper three pairs of false 

 ribs has its cartilage attached to the cartilage above 

 it, and are called vertebrochondral ribs; the last two 

 pairs are attached to the vertebra behind and their 

 anterior extremity is free; they are called floating or 

 vertebrarribs. 



FIG. 41 



For posterior costotransverse ligament. 



For anterior costotransverse ligament. 



Facet for body of 

 upper thoracic vertebra. 

 Ridge for inter- 

 articular ligament. 

 Facet for body of 

 lower thoracic vertebra. 



For transverse process of 

 lower dorsal vertebra. 



Vertebral extremity of a rib; external surface. (Gray.) 



A Typical Rib. Each rib has an anterior and pos- 

 terior extremity. The anterior extremity is hollowed 

 into a pit for union with the costal cartilage. The 

 posterior extremity is divided into a head, a neck, and 

 a tuberosity. The head has an upper and lower artic- 

 ular facet for articulation with the two vertebrae, 

 above and below; and between the two facets a ridge 

 for the attachment of the interarticular ligament. 



