194 



ALUS. [Vol. XVIII. 



hind end of this fascia a strong tendon runs directly backward, 

 and, separating at its hind end into two heads, is inserted on the 

 adjoining inner surfaces of the preoperculum and quadrate. The 

 two heads of the tendon here straddle the internal surface of the 

 svmplectic, one being inserted in front of that bone and the other 

 behind it. The rami mandibularis externus and internus facialis 

 pass between the two heads of this tendon and then reach the 

 lateral surface, or lower edge of the tendon. The two nerves thus 

 lie antero-lateral to the preopercular head of the tendon, and 

 postero-mesial to its quadrate head. Immediately dorsal to the 

 point where this tendon has its origin from the fascia on the inner 

 surface of A^ , that fascia is joined by parts of the tendons of 

 A^, A2 and A^, as already described. From the lateral or deep 

 surface of the fascia, part of the fibers oi A^ arise. Other fibers 

 of the muscle arise from one of the two tendons of An ; others 

 directly from, and as a continuation of, the fibers oi A^; and still 

 others, a small bundle at the postero-ventral corner of the muscle, 

 from a tendon that has its origin on the inferior end of the 

 preoperculum. The dorsal fibers of the muscle run upward and 

 forward, the middle ones forward, and the ventral ones down- 

 ward and forward. All of them are inserted on the inner sur- 

 faces of the articular and dentary, on the skin that covers the 

 lower edge of the dentary, and on a strong membrane that covers 

 Meckel's cartilage throughout its entire length. This latter 

 membrane seems much too strong to be simply the perichondria! 

 membrane of the cartilage, but it apparently includes that mem- 

 brane. The cartilage lies in it, imbedded in the outer, lateral 

 surface of A ^, none of the fibers of the latter muscle being in- 

 serted directly onto the cartilage. 



/4i is innervated by a branch of the ramus maxillaris inferior 

 trigemini given oft" just as that nerve passes outward around the 

 anterior edge of the levator arcus palatini. AnA^ is innervated 

 by another branch of the same nerve, given off at the same place. 

 The branch to A^ enters that muscle on its mesial surface. The 

 branch to /^a^s enters that muscle on its lateral surface. The 

 maxillaris inferior, after giving off these two branches, continues 

 downward and forward between the two muscles and enters the 

 mandible, where branches are sent to A ^. 



