A22- Muscles of Massication Flashcards
What is the process of chewing?
Mastication
Why do we need to break down food stuff?
- in preparation of swallowing
- increase surface area for digestion
- to release chemicals for the sense of taste
What does saliva do?
neutralises acid from food and plaque
What muscle originates from the zygomatic arch and inserts into the angle of the mandible?
masseter
what is the primary and secondary function of the masseter?
primary - jaw elevation
secondary - minor protrusion
What is he innervation of masseter?
Vc motor root
What is the origin and instertion of temporalis?
origin - inferior temporal lines
insertion - coronoid process
what is the function of temporalis?
jaw elevation and retrusion
The CN V3 motor root supplies innervation to which muscles of mastication?
masseter temporalis medial and lateral pterygoids mylohyoid anterior belly of digastric
The upper head of the lateral pterygoid originates and inserts where?
origin - infra-temporal surface of the greater wing if the sphenoid
insertion - capsule and articular disc of TMJ
What is the only muscle that does not cause jaw elevation and what does it do?
lateral pterygoid, it assists opening
What muscle inserts into the head of the condyle and originates from the lateral aspect of the lateral plate?
the lower head of the lateral pterygoid
What is the complex action of the lateral pterygoid inferior head?
it pulls the condyle forward
bilaterally - protrusion and opening
unilaterally - lateral excursion
What is the origin and insertion of the medial pterygoid?
origin - medial aspect of the lateral plate
insertion - medial aspect of the angle of the mandible
What is the function of the medial pterygoid?
jaw elevation (protrusion and lateral excursion)
What muscles attach from the mandible to the hyoid?
genohyoid
mylohyoid
anterior belly of digastric
What is the origin and insertion of the genohyoid?
origin - inferior mental spine an inferior genial tubercle
insertion - hyoid bone
Describe the action of the genohyoid when the hyoid is fixed and loose.
fixed - jaw opening
loose - raises the hyoid up and out
What is the innervation of the genohyoid
C1 (with hypoglossal)
What is the origin and insertion of the mylohyoid?
origin - mylohyoid line on the internal aspect of the mandible
insertion - via the median raphe into the hyoid
Describe the action of the mylohyoid when the hyoid is fixed and loose.
fixed - jaw opening
loose - raise the hyoid and the floor of mouth
What are the other accessory muscles involved in mastication?
orbicularis oris
buccinator - keeps food in the mouth and directs food
What is the origin and insertion the anterior belly of digastric?
origin - digastric fossa
insertion - hyoid bone
Describe the action of the anterior digastric when the hyoid is fixed and loose.
fixed - jaw opening
loose - raise hypoid
What are the hyoid stablisers?
stylohyoid
posterior belly of digastric
infrahyoids (omohyoid, strernohypid, thyrohyoid)
