oral function : muscles Flashcards
masseter action, examined by, origin and insertion
action - elevates mandible
examined by - placing one finger intraorally and one on cheek at points of origin and insertion
origin - zygomatic arch
insertion - lateral surface of angle of mandible
temporalis action, examined by, origin and insertion
action - elevate and retract
examined by - palpating origin whilst patient clenches
origin - floor of temporal fossa
insertion - coronoid process and anterior border of ramus
medial pterygoid action, examined by, origin and insertion
action - elevates and assists protrusion
examined by - no reliable way
origin - (deep head - medial surface of lateral pterygoid plate) (superficial head - tuberosity of maxilla)
insertion - medial surface of angle of mandible
lateral pterygoid action, examined by, origin and insertion
action - protrudes and deviates mandible laterally
examined by record response to resisted movements
origin - lateral surface of lateral pterygoid plate
insertion - anterior border of condoyle (inferior belly) and intra articular disc (superior belly)
trismus
difficulty opening jaw
posselts envelope of movement
shows mandible movement - rotation, translation, closing
TMJ movement - rotation
initial opening , hinge movement
like rotating around axis of the two condoyles
TMJ movement - translation
wider opening , protrusive and retrusive movements
protrusion - condyles leave fossae and slide towards articular eminences
retrusion - condyles leave eminences and slide back into their fossae
where in the mouth is greatest bite force found
between the first molars
positioned close to TMJ and force generating muscles , also wide root area so greater PDL support
what are the 4 suprahyoid muscles
digastric
mylohyoid
geniohyoid
stylohyoid
what are the 4 infrahyoid muscles
sternohyoid
ornohyoid
thyrohyoid
sternothyroid
origin vs insertion of a muscle
origin = attached to a immovable part insertion = attached to a moveable part
