0350 ch 23-Tab 10/12/04 12:19 PM Page 1 Chapter 23: The Temporomandibular Joint 1 TABLE 23-1 Muscles and Nerves of the Mandible MUSCLE AND NERVE (N) ORIGIN INSERTION FUNCTION Digastric N: trigeminal Anterior belly: depression Common tendon to the Mandibular depression and and facial on inner side of inferior hyoid bone elevation of hyoid border of mandible (in swallowing) Posterior belly: mastoid notch of the temporal bone Temporalis N: Temporal fossa and deep Medial and anterior Elevates mandible to close the mandibular division surface of temporal coronoid process and mouth and approximates teeth of trigeminal nerve fascia anterior ramus of (biting motion); retracts the mandible mandible and participates in lateral grinding motions Masseter N: Superficial: zygomatic Angle and lower half of Elevates the mandible; active in up mandibular division arch and maxillary process lateral ramus and down biting motions and of trigeminal nerve Deep portion: zygomatic Lateral coronoid and occlusion of the teeth arch superior ramus in mastication Medial pterygoid N: Greater wing of sphenoid Medial ramus and angle of Elevates the mandible to close mandibular division and pyramidal process mandibular foramen the mouth; protrudes the mandible of trigeminal nerve of palatine bone (with lateral pterygoid). Unilaterally, the medial and lateral pterygoid rotate the mandible forward and to the opposite side Lateral pterygoid N: Superior: inferior crest of Articular disk, capsule, and Protracts mandibular condyle and mandibular division greater wing of sphenoid condyle disk of the temporomandibular of trigeminal nerve bones Neck of mandible and joint forward while the mandibular Inferior: lateral surface of medial condyle head rotates on disk; aids in pterygoid plate opening the mouth. Joint action of the medial and lateral pterygoid rotates the mandible forward and to the opposite side Mylohyoid N: Medial surface of Body of the hyoid bone Elevates the hyoid bone and mylohyoid branch of mandible, entire (floor of the mouth) tongue for swallowing; depresses the trigeminal nerve length the mandible when fixed Geniohyoid N: Mental spine of mandible Body of the hyoid bone Assists in depression of the ventral ramus of C1 mandible; elevates and protracts through hypoglossal the hyoid bone; moves the tongue nerve forward Stylohyoid N: facial Styloid process of Body of the hyoid bone Draws the hyoid bone upward temporal bone and backward in swallowing; assists in opening the mouth and participates in mastication Hall & Brody: Therapeutic Exercise: Moving Toward Function, 2nd Edition © 2005, Lippincott Williams and Wilkins.