TERMS USED IN THE DESCRIPTION OF BONES AND JOINTS. 51 



movable upon each other, the substance poured out between 

 them, not having apparently undergone much change. 



The fourth period extends from the fiftieth or sixtieth day, 



to the (ifth or sixth month. Daring this period the callus 

 has been changed from the state of spongy, to that of compact 

 bone. 



— The substance intermediate to the fragments, which present- 

 ed itself under the form of a line or septum between them, 

 becomes more consistent, presents a whiter hue, and is ossified 

 towards the end of this period ; and the permanent callus is 

 now completed. 



— The fifth period extends from the fifth or sixth, to the 

 eighth, tenth or twelfth month, during which time the whole 

 of the provisional callus is entirely removed, the object of its 

 formation having been effected, that of securely holding the 

 bones together like splints till the fractured surfaces become 

 firmly reunited. The periosteum resumes its usual thickness 

 and polish, and the muscles and tendons their entire freedom of 

 motion. 



— The internal plug of callus having been removed by absorp- 

 tion, the central cavity of the bone, the medullary membrane 

 and the marrow itself, present their usual appearance. — 



Of the Terms used in the Description of Bones and their 

 Articulations. 



The study of this subject has been rendered more difficult 

 by the unnecessary introduction of many hard words, but some 

 of these words are so generally used, that they ought to be 

 understood by the student of anatomy. 



The word process signifies any protuberance or eminence 

 arising from a bone. 



Particular processes receive names from their supposed resem- 

 blance to certain objects ; and their names are very often com- 

 posed of two Greek words ; thus the term coracoid, which is 

 applied to a well-known process, is derived from the Greek 

 words xo^«|,, a crow, and eido;^, resemblance. 



