S 3 r NA R THR OSIS 



263 



The articulations are divided into three classes synarthrosis, or immovable; 

 amphiarthrosis, or mixed; and diarthrosis, or movable joints. 



Synarthrosis (Immovable Articulation) . Synarthrosis includes all those artic- 

 ulations in which the surfaces of the boms are in almost direct contact, being 

 fastened together by an intervening mass of connective tissue, and in which there 



Periosteum 



Sutural ligament 



Cartilage 



Perichondrium 



FIG. 215. Section across the sagittal suture. 



Periosteum 



Fir.. 216. Section through the occipitosphenoid 

 sync'hondrosis of an infant. 



is no joint cavity and no appreciable motion. Examples of synarthrosis are the 

 joints between the bones of the cranium and of the face, excepting those of the 

 mandible. The varieties of synarthrosis are four in number sutura, schindylesis, 

 gomphosis, and synchondrosis. 





Ligament 



Intervertebral disk 



of fibrocartilage 



Articular cartilage 



FIG. 217. Diagrammatic section of a symphysis. 



The sutura is that form of articulation met with only in the skull, where the 

 contiguous margins of flat bones are apparently but not really in immediate 

 contact, a thin layer of fibrous tissue, sutural membrane, being interposed. This 

 membrane is continuous externally with the pericranium and internally with the 



Articular cartilage 



Synovial membrane 

 'rr~Capsular ligament 



FIG. 218. Diagrammatic section of ?, diarthrodial 

 joint. 



Synovial membrane 



Articular cartilage 



Intra-articular 

 fibrocartilage 



Capsular ligament 



FIG. 219. Diagrammatic section of a diarthrodial 

 joint, with an intra-articular fibrocartilage. 



dura. In some of the sutures the sutural membrane gradually disappears as 

 age advances and the two bones form an osseous fusion. Where the articulating 

 surfaces are connected by a series of processes and indentations interlocked, 



