96 PRACTICAL ANATOMY. 



of the external pterygoid plate, except a small strip at its lower and front part 

 It is inserted into the depression in front of the neck of the condyle. (Fig. 58.) 

 The action of this head is to draw the condyle forward ; at the same time the 

 upper head draws the cartilage forward. 



Concerning the noise patients frequently hear on opening the mouth, I would 

 say I can not now recall ever having read or heard a rational explanation of its 

 occurrence. The theory I advance above is more for the purpose of getting the 

 student aroused to the necessity of learning the origins and insertions of the 

 pterygoids than for mere theorizing. If I succeed even in this, the object of this 

 paragraph will have been accomplished. I found a cadaver in which the crack- 

 ing noise attended every time the mouth was passively opened. On dissection 

 I found the cartilage had contracted inflammatory adhesions to the dome of the 

 glenoid cavity. It was on this single case I founded the theory above advanced, 

 in lieu of an explanation for those noises in the temporo-mandibular articulation 

 concerning which every physician and dentist has been consulted by solicitous 



EMINENTIA ARTICULARIS 



POSTERIOR GLENOID TUBERCLE 



CORONOID PROCESS 



GLENOIO SYNOVIAL CAVITIES 



Interarticular flbro-cartil- 

 age into which is in- 

 serted the upper head of 

 the external pterygoid 



Insertion of the lower head 

 of the external pterygoid 



Insertion of the deep layer 

 of the masseter muscle 



Insertion of the superficial 

 layer of the masseter mus- 

 cle 



FIG. 58. SCHEMATIC. TEMPORO-MANDIBULAR ARTICULATION. 



This is assumed to represent the normal relation of condyle of mandible, and interarticular cartilage to the 

 * eminentia articularis when the mouth is closed. 



patients. A single case, however, is a mere bagatelle ; numerous cases by 

 different observers will be necessary to give the theory scientific sanction. 



/// dislocation of the condyle of the mandible, what muscles must be overcome / 



Practically all. Theoretically, the posterior part of the temporal and the deep 

 portion of the masseter. As a matter of philosophy, however, malposition of 

 the head of a bone immediately sets up tonic contraction in all the muscles of 

 the group, since pain in the joint is reported to the brain and contraction follows 

 in all the muscles in the articular nerve circuit. See Hilton's law in the intro- 

 ductory chapter. 



The temporal muscle has practically two portions : an anterior and a pos- 

 terior. The latter pulls the jaw backward ; the former, acting alone, would pull 

 the jaw forward. 



What are tJie propositions in tlic nerve -supply to the mitsc/cs of mastication f 



They are : 



i. Nerve-supply, sensory, both to the pulp of the teeth and to the gum 





