Upper Jaw
The upper jaw, or the maxilla with the upper teeth, is thestructure fixed to the skull, forming the palatal dome onthe arch of the alveolar process with the teeth. It formsa fixed wall of the vocal tract and does not belong to thearticulatory organs: yet it is a critical structure for speecharticulation because it provides the frame of referencefor many articulatory gestures. The structures of the upper jaw offer the location for contact or approximation bymany parts of the tongue such as the apex, blade, and dorsum. The phonetics literature describes the place of articulation as classified according to the locations of lingualapproximation along the upper jaw for dental, alveolar,and palatal consonants. The hard palate is covered bythe thick mucoperiosteum, which has several transverselines of mucosal folds called thepalatine rugae.
The lower jaw, or the mandible with the lower teeth, isthe largest rigid motor organ among the speech production apparatus. Its volume is about 100 cm3. As well asplaying the major role in opening and closing the mouth,it provides attachments for many speech muscles andsupports the tongue, lips, and hyoid bone.
Figure10 shows the action of the jaw and the muscles used in speech articulation. The mandible articulateswith the temporal bone at the temporomandibular joint(TMJ) and brings about jaw opening–closing actions byrotation and translation. The muscles that control jawmovements are generally called the masticatory muscles. The jaw opening muscles are the digastric andlateral pterygoid muscles. The strap muscles, such asthe geniohyoid and sternohyoid, also assist jaw opening.The jaw closing muscles include the masseter, temporalis, and medial pterygoid muscles. While the largermuscles play major roles in biting and chewing, comparatively small muscles are used for speech articulation.The medial pterygoid is mainly used for jaw closing inarticulation, and the elastic recoil force of the connective tissues surrounding the mandible is another factorfor closing the jaw from its open position.
Figure 10a,b:Actions of the temporomandibular joint andmuscles for jaw opening and closing.(a) The lower jawopens by rotation and translation of the mandible at thetemporomandibular joint. Jaw translation is needed for wideopening of the jaw because jaw rotation is limited by the narrow space between the condyle and tympanic bone.(b) Jawopening in speech depends on the actions of the digastricand medial pterygoid muscles with support of the strapmuscles. Jaw closing is carried out by the contraction ofthe lateral pterygoid muscle and elastic recoil forces of thetissues surrounding the jaw
版权声明：本文为博主原创文章，未经博主允许不得转载。
，不然你大概会一直好奇和不甘吧——家门前的那条小路，
