TEMPORO-MAXILLARY ARTICULATION, 



1.33 



The internal lateral ligament, thin, loose, and elongated, lies at some 

 distance from the joint. It extends from the spinous process of the 

 sphenoid bone downwards and a little forwards, to be attached to the inner 

 border of the dental foramen in the inferior maxillary bone. Between it 

 and the lower jaw are placed the external pterygoid muscle, the internal 

 maxillary artery, and the inferior dental nerve. It has no immediate connec- 

 tion with the joint, and by some anatomists is not recognised as a ligament. 



The interarticular fibro- cartilage is a thin plate, placed between the 

 articular surfaces of the bones. It is of an oval form, broadest trans- 

 versely, thickest posteriorly, and thinnest at its centre, where it is sometimes 

 perforated. The inferior surface, which is in contact with the condyle, is 

 concave ; the superior is concavo-convex from before backwards, conforming 

 with the articular surface of the temporal bone. Its circumference is 

 connected at the outside with the external lateral ligament, and anteriorly 

 with the external pterygoid muscle. 



Fig. 123. 



Fig. 123. ANTERO-POSTERIOR 

 SECTION OP THE TEMPORO- 

 MAXILLARY ARTICULATION 

 OF THE RIGHT SIDE. 



1, is placed close to the 

 articular eminence, and points 

 to the superior synovial cavity 

 of the joint; 2, is placed 

 close to the articular surface 

 of the head of the lower jaw, 

 and points to the inferior 

 synovial cavity of the joint ; 

 x , is placed on the thicker 

 posterior portion of the inter- 

 articular nbro-cartilage. 



Synovial Membranes. 

 The synovial membrane 

 which lies between the 

 interarticular nbro-carti- 

 lage and the glenoid 



cavity is larger and looser than that which is interposed between the fibro- 

 cartilage and the condyle of the jaw. When the fibro- cartilage is perforated, the 

 upper and lower synovial cavities necessarily communicate one with the other. 



The stylo-maxillary ligament is the name given to a strong or thickened 

 band of fibres connected with the cervical fascia extending from near the 

 point of the styloid process to the posterior border of the ramus of the jaw, 

 where it is inserted between the masseter and internal pterygoid muscles. 

 It separates the parotid from the submaxillary gland. 



It may be proper also to mention in this place the stylo-hyoid ligament t 

 a thin fibrous cord, which extends from the point of the styloid process to 

 the lesser cornu of the hyoid bone, and serves to suspend that bone from the 

 styloid process. A considerable portion of the stylo-hyoid ligament is some- 

 times converted into bone in the human subject, and in animals it is naturally 

 osseous, and constitutes the epihyal bone. 



MOVEMENTS. The jaw is capable of movements of elevation and depression, of 

 some degree of lateral displacement, and of protraction and retraction ; but it is 

 to be observed that when the jaw is depressed, as in opening the mouth, the condyle 

 advances from the glenoid cayity so as to be placed on the articular eminence in front 



