1 E: Mastication Flashcards
Where are the muscles of mastication located?
What do they attach to?
- At various depths in the parotid and infra temporal regions of the face
- They attach to the mandible & receive their MOTOR innervation
What controls the motor innervation of the muscles of mastication?
The mandibular division of the trigeminal nerve CN V3
What are the muscles of mastication and name the most powerful one?
1) Masseter (Most powerful)
2) Temporalis
3) Medial Pterygoid
4) Lateral Pterygoid
What is the innervation of the Masseter muscle?
Masseteric branch of mandibular nerve
What is the innervation of the Temporalis?
Deep temporal branches of the mandibular nerve
What is the innervation of the Lateral Pterygoid?
Lateral Pterygoid branch of the mandibular nerve
What is the innervation of the Medial Pterygoid ?
Medial Pterygoid branch of the mandibular nerve
What is the action of the Masseter muscle?
Closes jaw by elevating mandible
What is the action of the Temporalis?
Elevates mandible and closes jaw
What is the action of the Lateral Pterygoid?
Opens mouth.
- Together= protrudes
- Alternately= grinding action
What is the action of the Medial Pterygoid ?
Elevates mandible, closing jaw
Together= protrudes mandible Solo= protrudes one side
What is Mastication?
The mechanical breakdown of ingested material by the teeth
What is chemical breakdown?
Ingested material is mixed w/ saliva
What is a bolus?
A soft, cohesive mass to be swallowed
What is the Masticatory Cycle?
Complex 3-dimensional movement resulting in a “looping” pattern
List the movements involving the jaw
1) Depression & elevation
2) Lateral movement
3) Anterior-posterior movement
***The TONGUE and HYOID BONE move in coordination w/ jaw movement
What are the 3 phases of jaw movement?
1) Opening
2) Closing
3) Occlusal
What occurs during “opening”?
The relaxation of jaw elevators; contraction of jaw openers
What occurs during “closing”?
Jaw elevates & turns to working side
What occurs during “Occlusal phase” ?
Jaw nears closure; STRONGEST forces are exerted; represents the LONGEST comment of the cycle
What is involved in Protrusion?
Lateral pterygoid assisted by medial pterygoid
What is involved in Retraction?
Posterior fibers of termporalis, deep part of masseter, & geniohyoid and digastric
What is involved in Elevation?
Temporalis, masseter, medial pterygoid
What is involved in Depression ?
Gravity, Digastric, geniohyoid, & mylohyoid muscles
