OP THE BONES. 377 



Many bones, broad as well as short, are formed of several 

 principal or original points of ossification, which unite more 

 or less quickly. Frequently these points correspond to dis- 

 tinct bones in other genera or classes of animals. Of this kind 

 are the points of ossification of the vertebrae, the occipital bone, 

 the sphenoid bone, the temporal bone, the maxillary bone, the 

 sternum, the coxal bones, the sacrum, &c. There even occurs 

 in the ruminating animals an example of the collateral union 

 of two long bones to form the cannon bone. 



597. Lastly, a great number of bones, especially of long 

 bones, and some broad and short bones, have accessory or se- 

 condary points of ossification, which are called epiphyses* on 

 account of their being implanted upon the body of the bone, 

 by means of a cartilage which lasts for a longer or shorter pe- 

 riod. The large long bones of the thigh, arm, leg, and fore- 

 arm, have at least one epiphysis at each extremity. 



The clavicle, the metacarpal, metatarsal and phalangeal 

 bones, have epiphyses at one extremity only. 



Of the broad bones, the coxal bones, and the scapulae, have 

 marginal epiphyses analogous to these terminal epiphyses of 

 the long bones. The ribs have epiphyses at their dorsal extre- 

 mity, and at their tubercle. 



Of the short bones, the vertebrae are almost the only ones 

 that have epiphyses; they have them at the two faces of their 

 body, and at the summit of all their processes which are not 

 articular. Of the other short bones, the calcaneum is the only 

 one that has an epiphysis. It is situated at its posterior extre- 

 mity. 



The epiphyses begin to form at very different periods, from 

 about fifteen days before birth, to fifteen or eighteen years 

 after, and remain for a longer or shorter time distinct before 

 uniting with the body of the bone. The periods at which they 

 unite are comprehended between the fifteenth and twenty-fifth 

 year. Of all the epiphyses, the one which ossifies first, is that 

 of the lower extremity of the femur, ossification commencing 



* Plainer. De Ossium Epiphysibus, 1736. Ungebauer. Epistola dc 

 Ossium trunci carp. hum. Epiphysibus Sero Onsets carundemquc Genesi. Lips. 

 1739. Beclard, foe, cit. 



