THE HEAD AND NECK 



I2I5 



part of the internal maxillan,'^ arter^'- rests upon it, and separates it 

 from the neck of the mandible; and inferiorly the inferior dental 

 vessels and ner\e and the auriculo-temporal nerve intervene between 

 it and the ramus of the mandible. At its lower attachment it is 

 spread over the upper end of the mylo-hyoid groove, and is here 

 pierced by the mylo-hjoid nerve and artery. This ligament is 

 sometimes spoken of as the long internal lateral ligament, in con- 

 tradistinction to the internal portion of the capsule, which is 

 regarded as the short internal lateral ligament. 



The spheno-mandibular ligament represents a portion of the fibroas invest- 

 ment of Meckel's cartilage. 



The stylo-mandibular ligament is a stout process of the deep cervical 

 fascia, which extends from the styloid process of the temporal bone 

 near its tip to the angle and adjacent portion of the posterior border 

 of the ramus of the mandible. Superiorly it gives origin to a few 

 fibres of the styloglossus, and inferiorly it is implanted between the 

 masseter and internal pterygoid muscles. It separates the sub- 

 maxillary gland from the lower portion of the parotid gland. 



Capsular Ligament 



Styloid Process 



Zygoma 

 Coraooid Process 



Spheno-mandibular 



(Internal Lateral) 



Ligament 



Stylo-mandibalar Ligament— ~— — 



Mylo-hyoid Groove 



Fig. 497. — The Temporo-Mandibolar Joint (Internal View). 



The interarticular fibro-cartilage is an oval plate which is inter- 

 posed between the t\vo articular surfaces. It is thinnest at the 

 centre, where it is occasionally perforated, and thickest posteriorly. 

 Its superior surface is concavo-convex from before backwards, in 

 adaptation to the convexity of the eminentia articularis and the 

 concavity of the glenoid fossa. Its inferior surface is concave, and 

 fits upon the condyle of the mandible. Its circumference is con- 

 nected with the capsular ligament, and anteriorly it gives partial 



