-402 GENERAL ANATOMY. 



633. The supernumerary articulations* have long been 

 known. They occur after fractures in which the fragments 

 have not been brought together, and those of which the frag- 

 ments have been frequently moved on each other. Sometimes 

 also the defect of union depends upon a constitutional affection. 

 The ends of the bones, which have a different configuration, 

 and have become compact and closed as after amputation, are 

 covered with a thin layer of imperfect or fibrous cartilage. 

 They are covered and enveloped by a synovial membrane, 

 surrounded by a fibrous capsule, generally incomplete and 

 with irregular ligamentous cords. This kind of articulation 

 has been observed, with a great number of variations, in al- 

 most all the long bones of the limbs, and several times in the 

 lower jaw and ribs. 



634. The supplementary articulations have also been often 

 observed. They follow unreduced luxations, and especially 

 those of the femur and humerus. Foville and Pinel Grand- 

 champ presented me with an anatomical preparation which re- 

 presents an articulation of this kind that had been formed after 

 an unreduced luxation of the bones of the fore-arm behind the 

 humerus. 



In the articulations of which we here speak, there occurs 

 a depression in the point against which the head of the 

 luxated bone rests. The circumference of this point is 

 raised by an accidental ossification. Sometimes even there 

 also occurs a circular fibro-cartilaginous rim in it. This newly 

 formed cavity is covered with an imperfect or fibrous cartilage. 

 The head of the luxated bone is commonly flattened. The in- 

 terior of the articulation is lined by a very distinct synovial 

 membrane and moistened by synovia. There is a fibrous 

 capsule, formed by the remains of the old capsule, adhering 

 to the luxated bone, by the surrounding cellular tissue, and by 

 a new production. The old cavity contracts and becomes su- 

 perficial, and the cartilage diminishes, or even entirely disap- 



* J. Salzmann. De JLrthul. Analogis, quce fracturls Ossium superveniunt. 

 Argentor, 1718. Langenbech, Uber die Slldung wider naturlicher Geknkc 

 nach Knochcnbruchen, in der Neuen Biblfur die Chirurg. Getting 1 . 1815. 



