Muscles of Mastication Flashcards
where does the condyle sit?
glenoid fossa
behind articular eminence
what bone is the articular eminence apart of?
temporal bone
what TMJ movement is jaw opening?
hinge
what TMJ movement is wide jaw opening?
hinge and slide
what TMJ movement is protrusion?
slide
what TMJ movement is lateral excursion?
lateral movement and rotation around vertical axis
translation
dentate chewing forces?
70-150N
edentulous chewing forces?
4-55N
maximum clenching forces between molars?
500-700N
where do you find the muscles of mastication?
between skull and mandible
what are the muscles of mastication?
masseter
temporalis
medial pterygoid
lateral pterygoid
origin and insertion of the superficial masseter?
origin: zygomatic arch
insertion: angle/ ramus of mandible
action of the superficial masseter?
jaw elevation (closing)
minor protrusion
innervation of superficial masseter?
Vc motor root - masseteric nerve
origin and insertion of the deep masseter?
origin: inner aspect of zygomatic arch
insertion: angle/ ramus of mandible
action of deep masseter?
jaw elevation (closing)
innervation of deep masseter?
Vc motor root - masseteric nerve
origin and insertion of temporalis?
origin: inferior temporal line and fascia
insertion: coronoid process
action of temporalis?
jaw elevation and retrusion (posterior fibres)
innervation of temporalis?
Vc motor root - deep temporal nerve
origin and insertion of upper head lateral pterygoid?
origin: infratemporal surface of greater wing of sphenoid
insertion: capsule and articular disc of TMJ
origin and insertion of lower head of lateral pterygoid?
origin: lateral aspect of lateral pterygoid plate
insertion: pterygoid fovea below head of condyle
action of lateral pterygoid?
initial opening (hinge in lower joint space, suprahyoids only)
wide opening (anterior and inferior translation of condyle, assisted by inferior lateral pterygoids)
innervation of lateral pterygoid?
Vc motor root - nerve to lateral pterygoid
function of lower head of lateral pterygoid?
pulls condyle forward
bilateral protrusion and assisted opening
unilateral excursion
function of super head of lateral pterygoid?
active during retrusion and closing
origin and insertion of medial pteryoid?
origin: medial aspect of lateral pterygoid plate and maxillary tuberosity
insertion: medial aspect of ramus/ angle of mandible
action of medial pterygoid?
jaw elevation
assists protrusion and lateral excursions (unilateral)
innervation of medial pterygoid?
Vc motor root - nerve to medial pterygoid
origin and insertion of geniohydoid?
origin: inferior mental spine and inferior genial tubercle
insertion: hyoid bone
action of geniohyoid?
when hyoid fixed: jaw opening and retrusion
when hyoid not fixed: raise and forward hyoid
innervation of geniohyoid?
C1 (with hypoglossal)
where is the mylohyoid?
median raphe
action of mylohyoid?
when hyoid fixed: jaw opening
when hyoid not fixed: raise hyoid and FOM
innervation of mylohyoid?
Vc motor root - nerve to mylohyoid (branch of IAN)
origin and insertion of anterior belly of digastric?
origin: digastric fossa
insertion: intermediate tendon
action of anterior belly of digastric?
hyoid fixed: jaw opening
hyoid not fixed: raises hyoid
innervation of anterior belly of digastric?
Vc motor root - via nerve to mylohyoid (branch of IAN)
what are the hyoid stabalisers?
infrahyoids
posterior digastric
stylohyoid
what are the infrahyoids?
omohyoid
thyrohyoid
sternohyoid
what are other muscles involved in mastication?
orbicularis oris (oral sphincter)
buccinator (along with the tongue)
