TMJ and Face Muscles Flashcards
TMJ movements?
- depression (of mandible)
- elevation (of mandible)
- protraction (protusion)
- retraction (restrusion)
- lateral
depression of mandible
opening jaw
elevation of mandible
closing jaw
Protraction (protrusion)
pushing mandible forwards
Retraction (retrusion)
pulling mandible backwards)
Lateral
side to side movements
muscles involved in smiling?
- zygomaticus major and minor (4)
- Orbicularis oculi (2)
- Levator labii superioris (2)
- Levator anguli oris (2)
- Risoris (2)
zygomaticus major/minor
the smiling muscle.
- raises the mouth upward and outward – smiling, laughing
Orbicularis oculi
the squinting muscle.
-closes the eyelids, compresses the eye opening, encircles the eye – close, wink, tired.
Levator anguli oris
elevates the angles of the mouth at each corner
rasises the corners of the mouth
Risorius
the lower lip stretching muscle
- draws the lower lip down and outward – neck muscle – crying, terrified.
Masseter
the clenching muscle.
- used to clench teeth and with lower jaw – fear, yawn
Levator labii superioris
– the sneering muscle.
- raises the upper lip beneath the nostrils – disgust, disdain.
Triangularis
– the facial shrug muscle.
-pulls the corner of the mouth downward – sadness, crying, miserable
Depressor labii inferioris
– the lower lip curl muscle.
-pulls the lower lip down and out – around the lips – surprise
Mentalis
– the pouting muscle.
- raises and tightens the chin - sadness, fear
Orbicularis oris
– the lip tightener muscle.
- compress and purses the lips – circles the mouth – disdain, repulsion
Corrugator
– the frown muscle.
- compresses the skin between the eyebrows – frown, concern, concentration
Frontalis
– the brow lifting muscle.
- draws the scalp down, wrinkles, two sides – fear, smile.
Risorius/platysma
– the lower lip stretching muscle.
- draw the lower lip down and outward – neck muscle – crying, terrified.
facial nerves innervation
Muscles of Mastication
V (mandibular branch of trigeminal nerve) – motor and
sensory roles
• Muscles of facial expression
VII (facial nerve)
• Facial/skull sensory supply by cervical nerves
what are the muscles of mastication?
- temporalis
- masseter
- medial and lateral pterygoid
temporalis
actions on mandible:
- elevate and retract–>posterior, middle, anterior
attachments: temporal fossa to the coronoid process of the mandible
masseter
actions on mandible:
- elevate (superior superficial+deep)
- retract (deep)
attachments:
superficial: maxillary process of zygomatic bone to ramus of mandible
deep: zygomatic arch of temporal bone to ramus of mandible
lateral pterygoid
actions on mandible: protrusion/depression
attachments:
disk at the superior head: greater wing of sphenoid to neck of mandible
-inferior head: lateral pterygoid plate of sphenoid to neck of mandible
medial pterygoid
- more vertical than the horizontal (lateral pterygoid)
- actions on mandible: elevate/protrude (jaw closing muscle)
attachments
- superficial head: maxilla to internal surface of angle of mandible
- deep head: lateral pterygoid plate of sphenoid to internal mandible angle
what is the innervation for muscles of mastication?
innervated by the mandibular branch of trigeminal nerve CN V (jaw muscles)
what is the innervation for muscles of facial expression?
VII (facial nerve)
what does the TMJ allow movement for?
allows movement of the mandible (lower jaw) relative to the movement of the maxilla (upper jaw)
what are the articular surfaces of the TMJ
temporal bone: articular tubercle and mandibular fossa
mandible: condylar process (head)
TMJ position of rest?
3-4mm teeth separation
TMJ range of motion
40-50mm (3 fingers)
what happens when the jaw opens/closes?
no muscle contractions –>muscles relaxed
jaw closed –>muscles contracted
TMJ joint
synovial biaxial condylar joint
- loose but strong joint capsule
- attaches to margins of mandibular fossa on the temporal bone and the neck of the condylar process (of mandible)
TMJ joint is divided by?
an articular disc with 2 synovial membranes lining each cavity
TMJ articular disc
- wedge of fibrocartilage (not squishy but cushions joint)
- divides TMJ into superior and inferior compartments
- increases range of motion, congruency, absorbs shock
- concavoconvex shape to create better fit
what are the attachments of the TMJ articular disc?
lateral pterygoid (anteriorly) head of mandible (anteriorly) joint capsule (circumferentially)
TMJ ligaments
lateral TMJ ligament –>stretches TMJ joint capsule laterally –>prvents inferoposterior condylar displacement
stylomabindobular/sphenomandibular ligament –> accessory ligaments –> prevents excessive mandibular opening
what are the movements withing the TMJ
first stage: rotation
second stage: translation movement
first stage movement TMJ
hinge like rotation of mandibular condyle pm disc inferior compartment
-the articular disc and mandible move together
second stage movement of TMJ
anterior gliding of mandibular condyle and disc onto articular tubercle within fossa
-lateral pterygoid inserts into mandibular head and articular disc –>both pulled onto the articular tubercle
resting position of TMJ
- open packed jaw position, connective tissue loose
- medial/lateral pterygoid musles relaxed
- teeth not in contact, mouth slightly open
rotation of TMJ –> first half of mouth opening
condylar process rolls anteriorly
eccentric contraction of temporalis
-inferior lateral ptergyoid tenses, superior relaxed
TMJ Translation –>second half of mouth opening
dislocation can occur
-disc and condylar process glide anteriorly
superior/inferior lateral pterygoid contract
connective tissue is taught posteriorly
TMJ closure
disc and condylar process glide posteriorly
connective tissue returns to rest
stability at the TMJ
- mandible position most stable –>maximum congruency
- disc shape and attachments –> strongle attached, allows rotation/sliding movements
- lateral ligament prevents dislocation
- temporalis and lateral pterygoid muscles provide dynamic stability
