214 ARTICULATION OP THE LOWER JAW. 



of the lower jaw, and which, are covered with cartilage. 

 The other elements of this joint consist of, 



1. A capsular ligament, 



2. External and internal lateral ligaments, 



3. Interarticular cartilage, 



4. Two synovial membranes, 



5. Stylo-maxillary ligament, 



6. Intermaxillary ligament. 



The capsular ligament extends from the glenoid fissure 

 and zygomatic eminence to the neck of the lower jaw. It 

 consists of strong fibres, though it is deficient internally 

 and in front where the external pterygoid muscle is at- 

 tached. This ligament is connected internally with the 

 interarticular cartilage and synovial membranes, and ex- 

 ternally with the external and internal lateral ligaments. 



The external lateral ligament extends from the zygomatic 

 process of the temporal bone at its root, to the neck of the 

 condyle of the lower jaw, at its outer side. It is short and 

 narrow, and is regarded simply as a thickening of the cap- 

 sular ligament upon its external side. This ligament is 

 hid by the parotid gland. 



The internal lateral ligament extends from the spinous 

 process of the sphenoid bone to the spine, which overhangs 

 the posterior mental foramen ; it is longer and thinner than 

 the external, and serves to protect the inferior dental artery 

 and nerve, which are situated between this ligament and 

 the bone. 



The interarticular cartilage is situated within the joint 

 and divides it into two distinct cavities, which sometimes, 

 however, communicate by an opening in the centre. This 

 cartilage is 'oval transversely, and consists of concentric 

 fibres, very compact, and more distinct and thick at the cir- 

 cumference than at the centre. It is attached to the cap- 

 sular ligament, and by presenting a movable socket, is 

 believed to strengthen as well as to guard against dislo- 

 cations. 



Of the two synovial membranes, the larger is superior and 



