Human physiology . external pterygoids; theretraction by the simultaneous movement of the internal ptery-goids ; and the sideway movements by the alternate action of theexternal pterygoids on both sides (Fig. 52, A and B). The masticatory movement is regulated by the tactile sensibilityof the teeth and the buccal mucous membrane, and by the 156 PHYSIOLOGY CHAP. muscular sense of the muscles that come into play ; it is activatedl»y the motor roots of the third branch of the trigeminals, aided bythe hypoglossal and facial nerves. The immediate common centreof the masticatory movements, according
Human physiology . external pterygoids; theretraction by the simultaneous movement of the internal ptery-goids ; and the sideway movements by the alternate action of theexternal pterygoids on both sides (Fig. 52, A and B). The masticatory movement is regulated by the tactile sensibilityof the teeth and the buccal mucous membrane, and by the 156 PHYSIOLOGY CHAP. muscular sense of the muscles that come into play ; it is activatedl»y the motor roots of the third branch of the trigeminals, aided bythe hypoglossal and facial nerves. The immediate common centreof the masticatory movements, according to Schroder van derKolk, lies in the medulla oblongata; this view is not, however,supported by any definite anatomical evidence. Since the move-ment is complex and voluntary, its centre probably lies in the so-called motor zone of the cerebral cortex. In fact, the electricalexcitation of a circumscribed area in the lower lateral part of the(•( irtex of the anterior lobe of the brain in rabbits readily produces. FIG. 52.—A, internal pterygoid muscles viewed from outside. (G. D. Thane.) The massetermuscle, greater part of zygomatic arch, temporal muscle with coronoid process, and a largepart of the ramus of the jaw have been removed ; 1, external pterygoid, the figure is placedon the lower head ; 2, internal pterygoid. B, lower part of skull and face to show attach-ment from behind of pterygoids and some other muscles. (Bonrgery.) a, body of spheroid,beneath which are the posterior nares ; /», section through temporal bone ; c, hard palate ;il, posterior part of condyle and neck of lower jaw, above which are the synovial cavities ofthe joint separated by the inter-articular tibro-cartilage; c, symphysis ; 1, left internalpterygoid muscle; 1, lower part of same muscle, on right side, the middle is cut away toshow external pterygoid ; -I, lower head of external pterygoid ; 2, upper head of the muscle,attached in part to the inter-articular disc; 3, origin of mylo-hyoi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphysiology, bookyear1
