THE EIBS, 



27 



and indented at its lower part, as occurs especially from the pressure of the 

 cobbler's last. 



Two small nodules of bone, o.fm .mpra-^trmaJia, have been found in some rare 

 cases at the sides of the incisura close to the clavicular notches, sometimes being- 

 united by bone, at others by ligament to the sternum. (Breschet. " Annales des 

 Sciences Natui-elles," 2nd series, v. 10, p. 91 ; and Luschka, " Die Halsrippen und 

 die Ossa suprastemalia," Vienna, 185D.) Their position is indicated hy the 

 asterisks (**) in figure 26, E. They derive an additional interest from the occur- 

 rence of suprasternal bones in some animals. 



THE RIBS. 



The ribs (coskc), twelve in number on each side, constitute a series of 

 arched and highly elastic bones, which extend outwards and forwards 

 from the vertebral column, and form the lateral walls of the thorax. 

 Their anterior extremities give attachment to cartilaginous prolonga- 

 tions—the costal cartilages, the first seven pairs of which pass forward 



Fix. 23. 



Fig. 23. — The Fikst, Sixth, and Twelfth Ribs of the Right Side. (A. T.) ^ 



A, the sixth seen from above and the outer side ; B, the same rib viewed from below 

 and within ; C, the first rib viewed from above and without ; D, the twelfth rib viewed 

 from above and witliin. 



1, the head in C & D, the inter- vertebral ridge in B ; * *, the costo-central facets ; 

 2, the neck ; 3, tlie tubercle, in B presenting the rough tubercle and the smooth facet, 

 for articulation with the transverse process ; 4, the lower Ijorder with the ridge and sub- 

 costal groove ; 5, the upper border ; 6, the oval pit for the attachment of the costal 

 cai-tUage ; 7, in the first rib, C, the scalene tubercle or spine, and near it the smooth 

 groove for the subclavian artery. 



to the sternum. On this account the first seven pairs of ribs are called 

 sternal, and the remaining five pairs asternal ribs. Of these asternal 

 ribs each of the upper three has its cartilage attached along its superior 

 border to the cartilage of the rib above it, while the last two being 

 entirely free from such attachment are called floatm/ ribs. 



General characters of the ribs. — These are best marked in the 

 ribs near the middle of the series. The posterior extremity is thick- 

 ened, and is termed the head or capituhnn ; it presents a superior and 

 an inferior oblique articular surface for articulation with the bodies of 



