156 



THE RIBS. 



Fig. 38.* At the posterior end of 



each rib, a little head is 

 formed, which is divided 

 by a middle ridge into two 

 flat or hollow surfaces ; 

 the lowest of which is ge- 

 nerally the broadest and 

 deepest. The two surfaces 

 are joined to the bodies of 

 two different vertebrae, 

 and the ridge forces itself 

 into the intervening carti- 

 lages. A little way from 

 this head, we find, on the 

 external surface, a small 

 cavity, where mucilagi- 

 nous glands are lodged ; 

 and round the head, the bone appears spongy, where the 

 capsular ligament of the articulation is fixed. Immediately 

 beyond this, a flattened tubercle rises, with a small cavity at 

 its root, which is surrounded by a roughness, for the articula- 

 tion of the rib with the transverse process of the lowest of the 

 two vertebrae, with which the head of the rib is joined. 

 Advancing farther on this external surface, another smaller 

 tubercle may be observed in most cases, into which ligaments 

 connecting the ribs to each other, and to the transverse pro- 

 cesses of the vertebrae and portions of the longissimus dorsi, 

 are inserted. Beyond this, these bones are made flat by the 

 sacro-lumbalis muscle, which is inserted into the part of this 

 flat surface farthest from the spine, where each rib makes a 

 considerable curve, called by some its angle. Then the rib 



* An anterior view of the thorax. J . The superior piece of the sternum. 2. 

 The middle piece. 3. The inferior piece, or ensiform cartilage. 4. The first 

 dorsal vertebra. 5. The last dorsal vertebra. 6. The first rib. 7. Its head. 



8. Its neck, resting against the transverse process of the first dorsal vertebra. 



9. Its tuberosity. 10. The seventh or last true rib. 11. The costal cartilages of 

 the true ribs. 12. The two last false ribs the floating ribs. 13. The groove 

 along the lower border of the rib for the lodgment of the intercostal vessels and 

 nerve. 



