THE LIGAMENTS. 101 



Movements of the lower jaw; a. downwards. The condyles, 

 together with the menisci, roll from behind, forwards ; Ligam. 

 later, extern, is stretched; Lig. lat. intern, remains unchanged. 

 Drawing down the lower jaw too strongly, as for example in gap- 

 ing, may produce luxation, that is, a slipping of the condyle out 

 of the foss. glenoidal. into the zy go matic fossa. 



b. Upwards, that is, in closing the mouth. The movements of 

 the condyle the reverse of a. Luxation backwards is prevented 

 by the anterior wall of the auditory meatus, to which point the 

 condyles may roll, for example, in edentulous old age. 



c. Forwards (and backwards] horizontally: the articular head 

 comes below the transverse root of the proc. zygomat. But it 

 must be preceded by the movement downwards. All the liga- 

 ments are stretched. In too great extension the coronoid process 

 is opposed by the upper jaw, and farther luxation rendered im- 

 possible. 



d. From side to side. The condyle of one side passes side- 

 ways from its cavity, stretching its ligaments ; that of the other 

 sinks more deeply into its articular cavity, where a luxation in- 

 wards is prevented by proc. styloideus and its sheath, as well as 

 by proc spinosus. 



The movements c and d are more limited than a and b. 



115. Connections of the Thoracic cavity, Chest. 

 I. Vertebra with the ribs, Jlrticul. costo-vertebralis. 



a. Capitulum costse has a divided articular surface, which lies 

 in ihefovese costales, formed by the bodies of two dorsal vertebrae, 

 unites with the cartil. intervertebr., and forms a free articulation, 

 enarthrosis, not ginglymus. Its synovial capsule is single on 

 the first, eleventh and twelfth ribs, double on the rest ; articular 

 capsule incomplete. Instead of it : 



1. Lig. capituli anterius s. radiatum, stellate on the anterior surface of the 

 joint. 



2. Lig. capituli inferarticulare, on the second and to the tenth ribs, from 

 the cm/a of capituli to the cartil. inlerartic. , flat, oval, and separating the 

 two synovial capsules. 



b. Tubercuhim costse has a convex articular surface which 

 unites with one concave, on the proc. transvers. in a close joint. 

 Moreover, ligaments pass from collum costx to the proc. trans- 

 versi. 



1. Synovial capsule. 



2. Lig. tuberculi s. transversarium poslerius, quadrangular, behind the 

 joint ; ffom the apex of the proc. tramvers. to the posterior surface of the 

 Tutiercul. cos tee of the first to the tenth ribs inclusive. 



3. Lig. transversarium-intermedium, from the anterior surface of the proc. 

 transv. to the posterior of the collum costce very strong. 



