TEMPORO-MAXILLARY JOINT. 



91 



capsule, which is attached above to the tubercle at the root of the zygoma, 

 and below to the outer side of the neck of the inferior maxilla. 



The internal lateral ligament (h'g. 19, *) is a long, thin, membranous 

 band, which is not in contact with the joint. Superiorly it is connected 

 to a projection inside the glenoid fossa, which consists of the spinous pro- 

 cess of the sphenoid and the vaginal process of the temporal bone ; and 

 interiorly it is inserted into. the orifice of the dental canal in the lower jaw. 

 The ligament lies between the jaw and the internal pterygoid ; and its 

 origin is concealed by the external pterygoid muscle. Between the liga- 

 ment and the jaw the internal maxillary artery intervenes. 



Fit 



Fig. 20. 



LIGAMENTS OP THE JAW AN INNER VIEW 

 (Bourgery and Jacob). 



1. Internal lateral ligament. 



2 Stylo-maxillary. 



3. Stylo-inaxillary ligament. 



A VIEW OF THE INTERIOR OP THE COMPOUND 



TEMPORO-MAXILLARY JOINT (Bourgery and 

 Jacob). 



4. Interarticular fibro-cartilage the dark inter- 

 vals above and below are the hollows con- 

 taining the synovia] membranes. 



Dissection. After the external lateral ligament and the capsule of the 

 joint have been examined, an interarticular fibro-cartilage, with a hollow 

 above and below it, will be exposed by taking away the capsule on the 

 outer side (fig. 20). 



The interarticular fibro-cartilage (fig. 20, *) is adapted to the surfaces 

 of the bones. It is elongated transversely, is thinner in the centre than at 

 the margins, and an aperture is sometimes present in the middle. The 

 upper surface fits into the glenoid fossa, being concavo-convex from before 

 backwards, and the lower is moulded on the convexity of the condyle of 

 the jaw. By the circumference it is connected with the capsule and the 

 external lateral ligament ; and in front the external pterygoid muscle is 

 attached to it. 



This interarticular pad allows greater freedom of movement in the joint 

 without dislocation ; diminishes the injurious effect of pressure ; and dead- 

 ens the sound of the jaw striking the skull. 



Two synovial membranes are present in the articulation one above, 

 and one below the fibro-cartilage. The lower one is the smaller of the two. 



Another structure the stylo-maxillary ligament (fig. 20, 3 ) is described 

 as a uniting band to this articulation. It is a process of the deep cervical 

 fascia, which extends from the styloid process to the hinder part of the 

 ram us of the jaw : it gives attachment to the stylo-glossus muscle, ami 

 separates the parotid and submaxillary glands. i 



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