Muscles of Mastication Flashcards
skeletal bones (3)
maxilla
mandible
temporal bone
how many maxillary bones?
2
2 maxillary bones are fused together at the
mid palatal suture
superior border
floor of the nasal cavity and orbit
inferior border
palate and alveolar ridge
components of the maxilla
body
processes
maxilla processes (4)
zygomatic
frontal
alveolar
palatine
largest and strongest bone on the skull
mandible
components of the mandible (2)
body
ramus
superior aspect of the mandible
alveolar crest and teeth
body (posterior aspect) of the mandible (4)
mandibular angle
ascending ramus
-coronoid process
-condyle
what does the condyle articulate with
the cranium
condyle poles
medial and lateral
mediolateral length of the condyle
15-20 mm
anterior-posterior width of condyle
8-10 mm
squamous portion of the temporal bone articulates with the
mandibular condyle
temporal bone contains the — fossa
articular or glenoid fossa
articular eminence
thick dense bone to tolerate heavy forces
two heads of masseter
superficial: fibers run downward and backward
deep: fibers run in a vertical direction
masseter origin
zygomatic arch
masseter insertion
lateral surface of ramus and angle of the mandible
masseter function (4)
elevates the mandible
powerful muscle providing the force for chewing
superficial head: aids in protrusion
deep head: stabilizes the condyle against the eminence
masseter blood supply
a muscular branch of the maxillary artery
massester nerve supply
masseteric nerve of mandibular division of trigeminal nerve
temporalis divisions (3)
anterior: vertical directed fibers
middle: fibers run obliquely across lateral aspect of the skull
posterior: horizontal fibers come forward above the ear to join other temporals fibers
temporalis origin
temporal fossa and lateral surface of the skull
temporalis insertion
coronoid process and anterior border of ascending ramps
temporalis action (3)
anterior: mandible is raised vertically
middle: elevates and retrudes the mandible
posterior: aids in retrusion of the mandible
temporalis blood supply
a muscular branch of the maxillary artery
temporalis nerve supply
deep temporal nerve of the mandibular division of trigeminal nerve
lateral (external) pterygoid heads (2)
superior lateral pterygoid
inferior lateral pterygoid
superior lateral pterygoid and inferior lateral pterygoid are almost
2 separate muscles
inferior lateral pterygoid origin
outer surface of lateral pterygoid plate
inferior lateral pterygoid insertion
neck of condyle
inferior lateral pterygoid extends (3)
backward
upward
outward
inferior lateral pterygoid actions (2)
bilateral contraction: causes the condyles to be pulled down the articular eminences and the mandible is protruded
unilateral contraction: causes mediotrusive movement (downward, forward, medially)
smallest of the two bellies
superior lateral pterygoid
superior lateral pterygoid origin
infra temporal surface of the greater sphenoid wing
superior lateral pterygoid insertion
disk, capsule, and neck of the condyle
superior lateral pterygoid action (3)
inactive during mandibular opening
active only with elevator muscles (closure of the mandible)
power stroke
power stroke
this muscle is active during mandibular closure against resistance (chewing or clenching)
lateral pterygoid blood supply
a muscular branch of the maxillary artery
lateral pterygoid nerve supply
a branch of the masseteric or buccal nerve of the mandibular division of the trigeminal nerve
medial internal pterygoid origin
pterygoid fossa
medial internal pterygoid insertion
medial surface of the mandibular angle
medial internal pterygoid function (3)
elevates the mandible
protrudes the mandible
unilateral contraction
medial internal pterygoid function results in
mediotrusion
medial internal pterygoid blood supply
a muscular branch of the maxillary artery
medial internal pterygoid nerve supply
a motor branch of the mandibular division of the trigeminal nerve which reaches the posterior borer of the muscle near the base of the skull
masseter sling (2)
masseter
medial pterygoid
supra hyoids as a group (4)
geniogyoid
mylohyoid
digastric
stylohyoid
supra hyoids function (2)
elevate hyoid bone
depress the mandible when hyoid bone is fixed
geniohyoid origin
inferior genial tubercle on the inner surface of mandibular symphysis
geniohyoid insertion
anterior surface of body of hyoid bone
mylohyoid origin
line from last molar root to mandibular symphysis
mylohyoid insertion
median raphe from chin to hyoid bone
digastric bellies (2)
anterior
posterior
digastric origin (2)
the posterior belly, longer than the anterior, arises from the mastoid process
the anterior belly arises from a depression on the inner side of the lower border of the mandible, close to the kyphosis
digastric insertion
hyoid bone
depression of the mandible:
contraction (2)
relaxation (3)
contraction:
inferior lateral pteryhoids
digastric
relaxation:
masseters
medial pterygoids
temporalis
elevation of the mandible:
contraction (4)
relaxation (2)
contraction: masseters medial pterygoid temporalis superior lateral pterygoid
relaxation:
inferior lateral pterygoid
digastric
right lateral movement:
contraction (1)
relaxation (2)
contraction:
left inferior lateral pterygoid
relaxation:
right inferior lateral pterygoid
slight relaxation of elevators
left lateral movement:
contraction (1)
relaxation (2)
contraction:
right inferior lateral pterygoid
relaxation:
left inferior lateral pterygoid
slight relaxation of elevators
protrusion
contraction:
inferior lateral pterygoids mainly
assisted by masters and medial pterygoids
retrusion
contraction:
temporalis