Temporomandibular joint muscles of mastication mimetic muscles DAVID

Temporomandibular joint, muscles of mastication, mimetic muscles DAVID DORA assistant lecturer 2017. 12. 11

Mandible

Condylar process Caput mandibulae Coronoid process Oblique line Mandibular ramus Neck of the mandible Mental formamen Alveolar part Mental protuberance Angulus mandibulae Mandibular foramen Sup. and Inf. Mental spine Mylohyoid line

Zygomatic process Carotid canal Articular tubercle Stylomastoid foramen Mastoid process Petrotympanic fissure Mandibular fossa Styloid process

Temporomandibular joint Articular tubercle Mandibular fossa Two subjoints: disco - temporal articulation (post. ); disco-mandibular articulation (ant. ) The type of joint: by shape: cylindrical joint, by function: restricted joint (rigid) (amphiartrosis) Capsule: relatively lax, allows the protrusion of the mandibular head and its luxation as well Mandibular caput Articular disc • posteriorly it spreads to the petrotympanic fissure (Glaseri), sorrounding the head and the collum • the posterior capsule is abundant in elastic fibers causing the passive retraction of the head during elevation of the mandible (during the closure of the mouth)

• Lateral temporomandibular lig: between the zygomatic process and the mandibular collum • Sphenomandibular lig: between sphenoidal bone and mandibular canal • Stylomandibular lig: between styloid process and mandibular angle Pterygospinal lig. Lateral ligament Articular capsule Sphenomandibular lig. Stylomandibular lig. Pterygoid process lamina lateralis Pterygoid process lamina medialis

Muscles of mastication Temporalis muscle Masseteric muscle superficial part Masseteric muscle deep part Lateral pterygoid muscle

Lateral pterygoid muscle caput sup. et inf. Medial pterygoid muscle Lateral pterygoid muscle Medial pterygoid muscle

Movements of the temporomandibular joint Depression (opening of mouth): 2 phases a) Rotation of mandibular caput in the discomandibular joint –axis: transversal axis going through the 2 caputs max. 15 degrees b) The head of the mandible and the articular disc slide anteriorly onto the articular tubercle in the discotemporal joint –axis: transversal axis between the two mandibular foramens participating muscle: lateral pterygoid Elevation (closing of mouth): Other muscles of mastication: temporalis muscle, masseteric muscle, medial pterygoid so-called „biting muscles”

Articular tubercle Caput mandibulae Closed mouth Lateral pterygoid caput superior Lateral pterygoid caput inferior Open mouth until 15 degrees Articular disc Articular capsule Open mouth after 15 degrees

Protrusion – Retrusion of the mandible: Transversal axis between the two mandibular foramens 1 cm anteriorly, less than 1 mm posteriorly (the mandibular caput hits the external acustic meatus) Protrusion: Lateral pterygoid + (anterior part of temporalis muscle) Retrusion: masseteric muscle, temporalis muscle, medial pterygoid muscle

Lateral movements: The mandibular caput rotates around a vertical axis as well (alternating on the ipsi- and the contralateral side „resting condyle” „swinging condyle”) one condyle is just rotating (resting), the other on the other side (swinging) is pulled anteriorly and medially Muscles: protrusion: Lateral pterygoid; retrusion: temporalis muscle posterior part Bennet angle: 7, 5 -12, 5 degrees

External acustic meatus Mandibular caput Temporalis muscle Articular disc Lateral pterygoid muscle caput sup. and inf. Medial pterygoid muscle Buccinator muscle SCM Mastoid process Masseteric muscle

Mimetic muscles

Muscles of facial expression I. Muscles on the calvaria II. Muscles of the auricle III. Muscles around the eyes IV. Muscles of the nose V. Muscles around the mouth VI. Platysma Mimetic muscles are innervated by the facial (VII) nerve

Occipitofrontalis (epicranius) caput frontalis et occipitalis Sup. auricular m. Galea aponeurotica Temporoparietal m. Ant. Auricular m. Post auricular m. SCM Platysma

Corrugator supercili m. Procerus m. Levator labii superioris aleque nasi m. Nasalis m. Orbicularis oculi m. orbital part Orbicularis oculi m. palpebral part

Levator labii superioris m. Risorius m. Zygomaticus minor m. Zygomaticus major m. Levator anguli oris m. Orbicularis oris m.

Buccinator m. Masseteric m. Depressor anguli oris m. Mentalis m. Depressor labi inferioris m.

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