Articulator/Muscles of Face Flashcards
What is an articulator?
A mechanical device that simulates mandibular movements of condyles in their fossae
What are the parts of functional anatomy?
- dentition and supportive structures
- skeletal components
- temporomandiular joints
- ligaments
- muscles
What are the parts of the skeleton (face)?
maxillar
mandibule
temporal bone
What are the features of the maxilla?
- 2 maxillary bones (fused at mid-palatal suture)
What is the superior border of the maxilla?
floor of the nasal cavity and orbit
What is the inferior border of the maxilla?
palate and alveolar ridge
What are the components fo the maxilla?
- body
- processes (zygomatic, frontal, alveolar, palatine)
What is the largest and strongest bone on the skull?
mandible
What are the components of the mandible?
body
ramus
What are the parts of the body of the mandible?
mandibular angle
ascending ramus
- coronoid process
- condyle
Where does the condyle of the mandible articulate?
the cranium
What is the mediolateral length of the condyle of mandible?
15-20 mm
What is the anterior-posterior width of the condyle mandible?
8-10 mm
What does the squamous portion of the temporal bone articulate with?
mandibular condyle
What is the articular eminence?
thick dense bone to tolerate heavy forces
What are the four main muscles of mastication?
lateral pterygoids
medial pterygoid
masseter
temporalis
What are the two heads of the masseter?
superficial (fibers run down and back)
deep (fibers run vertical)
What is the origin of the masseter?
zygomatic arch
What are the insertions of the masseter?
lateral surface of ramus
angle of the mandible
What is the function of the masseter?
- elevates the mandible
- provides the force for chewing
What is the function of the superficial head of the masseter?
aids in protrusion
What is the function of the deep head of masseter?
stabilizes the condyle against the eminence
What is the blood supply to the masseter?
muscular branch of the maxillary artery
What is the nerve supply to the masseter?
masseteric nerve of mandibular division of trigeminal nerve
What are the three distinct divisions of the temporalis?
anterior (vertical fibers)
middle (oblique fibers)
posterior (horizontal fibers)
What is the origin for the temporalis?
temporal fossa and lateral surface of the skull
What is the insertion of the temporalis?
coronoid process
anterior border of ascending ramus
What is the action of the anterior temporalis?
mandible is raised vertically
What is the action of the middle temporalis?
elevates and retrudes the mandible
What is the action of the posterior temporalis?
aids in retrusion of the mandible
What is the blood supply of temporalis?
a muscular branch of the maxillary artery
What is the nerve supply of temporalis?
deep temporal nerve of the mandibular division of trigeminal nerve
How many heads does the lateral (external) pterygoid have?
2 heads
- superior lateral pterygoid
- inferior lateral pterygoid
What is the origin of the inferior layeral pterygoid?
outer surface of the lateral pterygoid plate
What is the insertion of the inferior lateral pterygoid
neck of condyle
What are the actions of the inferior lateral pterygoid?
bilateral contraction (mandible is protruded)
unilateral contraction (mediotrusive movement)
What is the superior lateral pterygoid origin?
infratemporal surface of the greater sphenoid wing
What is the superior lateral pterygoid insertion?
disk, capsule, and neck of the condyle
What is the action of the superior lateral pterygoid?
active with elevator muscles (closure of the mandible)
- power stroke
What is the blood supply for the lateral pterygoid?
muscular branch of the maxillary artery
What is the nerve supply for the lateral pterygoid?
branch of the masseteric or buccal nerve of the mandibular division of the trigeminal nerve
What is the origin of the medial (internal) pterygoid?
pterygoid fossa
What is the insertion of the medial (internal) pterygoid?
medial surface of the mandibular angle
What is the function of the medial (internal) pterygoid?
- elevates the mandible
- protrudes the mandible
- unilateral contraction
What is the blood supply to the medial (internal) pterygoid?
muscular branch of the maxillary artery
What is the nerve supply of the medial (internal) pterygoid?
motor branch of the mandibular diviosn of the trigeminal nerve, which reaches the posterior border of the muscle near the base of the skull
What are the two parts of the masseter sling?
masseter
medial pterygoid
What are the suprahyoid muscles?
geniohyoid
mylohyoid
digastric
stylohyoid
What are the functions of the suprahyoid muscles?
- elevate hyoid bone
- depress the mandible when hyoid bone is fixed
What is the origin of the geniohyoid?
inferior genial tubercle on the inner surface of mandibular symphysis
What is the insertion of the geniohyoid?
anterior surface of body of hyoid bone
What is the origin for the mylohyoid?
line from last molar root to mandibular symphysis
What is the insertion of the mylohyoid?
median raphe from chin to hyoid bone
What are the two bellies of the digastric muscle?
anterior
posterior
What are the two origins of the digastric muscle?
- posterior belly from the mastoid process
- anterior belly from a depression on the inner side of the lower border of the mandible, close to the symphysis
What is the insertion of the digastric muscle?
hyoid bone
What muscles depress the mandible via contraction?
- inferior lateral pterygoids
- digastric
What muscles depress the mandible via relaxation?
- masseters
- medial pterygoids
- temporalis
What muscles elevate the mandible via contraction?
- masseters
- medial pterygoid
- temporalis
- superior lateral pterygoid
What muscle elevates the mandible via relaxation?
- inferior lateral pterygoid
- digastric
What muscle provide right lateral movement via contraction?
- left inferior lateral pterygoid
What muscles provide right lateral movement via relaxation?
- right inferior lateral pterygoid
- slight relaxation of elevators
What muscle provides left lateral movement via contraction?
- right inferior lateral pterygoid
What muscles provide left lateral movement via relaxation?
- left inferior lateral pterygoid
- slight relaxation of elevators
What muscles allow for protrusion via contraction?
- inferior lateral pterygoids (mostly)
- assisted by masseters and medial pterygoids
What muscle allows for retrusion via contraction?
temporalis