Bones of the Trunk. 



Tubercultim, 



lum 



90. The First Rib, superior view. 



The first rib shows an upper and an under surface, an outer 

 and an inner border. It has a round head, Capitulum, with a single articular 

 facet, when the first dorsal vertebra alone forms the articular fossa; 

 when the articular fossa is formed by the seventh cervical and first 

 dorsal vertebrae, the articular facet of the head is also a double one. 

 At the inner border there is a tubercle, the Tuberculum Lisfrancii, 

 which is not always very well developed. 



