PECULIAR RIBS. 



23o 



Development. Each rib, with the exception of the last two, is developed by 

 three centres : one for the shaft, one for the head, and one for the tubercle. The 

 last tw have only two centres, that for the tubercle being wanting. Ossification 

 commences in the shaft of the ribs at a very early period, before its appearance in 

 the vertebne. The epiphysis of the head, which is of slightly angular shape, and 

 that for the tubercle, of a lenticular form, make their appearance between the six- 



FIG. 



\\gleat-f 



FIG 



Angle 



slightly marked 



and close to 



htberosity. 



FIG. 189. 

 Single articular facet. 



FIG. 190. 

 Fingle articular facet ^- 



FlG. 191. 

 Single articular facet. 



FIGS. 187-191. Peculiar ribs. 



teenth and twentieth years, and are not united to the rest of the bone until about 

 the twenty-fifth year. 



Attachment of Muscles. The Internal and External intercostals, Scalenus 

 anticus. Scalenus medius, Scalenus posticus, Pectoralis minor, Serratus magnus, 

 Obliquus externus, Obliquus internus, Transversalis. Quadratus lumborum. Dia- 

 phragm, Latissimus dorsi, Serratus posticus superior, Serratus posticus inferior, 

 Ilio-costalis. Musculus accessorius ad ilio-costalem. Longissimus dorsi. Cervicalis 

 ascendens. Levatores costarum, and Infracostales. 



