TMJ and Muscles of Mastication Flashcards
what are the parts of the mandible
body, ramus, angle, coronoid process, condylar process
what is the area between the 2 mandibular processes called
mandibular notch
what is the mental protuberance
prominent part of chin
what is the mental foramina
foramen for nerves and blood vessels
what is the mandibular symphysis
where 2 sides of mandibles fuse
where is the mandibular foramina
in the medial side where IAN travels
how is the mylohyoid line clinically relevant
if dental infection travels inferior to the line it spreads to floor of mouth and submandibular region causing LUDWIGS ANGINA
dentures also need to stop anterior to the line as it attaches to mylohyoid
what is the mylohyoid groove
where the nerve to mylohyoid passes through
where does the mandible articulate with the skull
at the mandibular fossa of the temporal bone just anterior to external acoustic meatus
what is the TMJ comprised of
mandibular fossa of temporal bone and condylar process of mandible
what type of joint is the TMJ
modified hinge synovial joint
how is the TMJ an atypical joint
as fibrocartilage covers the bony surfaces instead of hyalinecartilage
what are the different cavities of the TMJ
superior and inferior articular cavities
what type of dislocation occurs most commonly with the TMJ
anterior dislocation
what are the 2 types of ligament in the TMJ and how many of each are there
2 extrinsic and 1 intrinsic
what are the 2 extrinsic ligaments of the TMJ
sphenomandibular and stylomandibular
what is the intrinsic ligament in the TMJ
lateral ligament
what is the function of the sphenomandibular ligament
primary passive support of the mandible, supports movement as acts as fulcrum
where does the sphenomandibular ligament attach
spine of sphenoid to lingula on medial side of mandible
where does the stylomandibular ligament attach to
styloid process to angle of mandible
what is the function of the lateral ligament
strengthens TMJ laterally, prevents dislocation
what does the lateral ligament work with to prevent dislocation
postglenoid tubercle
when is the TMJ most unstable and why
during depression as condylar processes move anteriorly and lie underneath articular eminences with mandibular head vulnerable to dislocation
what are the 5 movements of the mandible
protrusion, retraction, elevation, depression, lateral movements
what muscle protrudes the mandible
lateral pterygoid
what muscle retracts the mandible and what cavity does it occur in
temporalis, in superior cavity
what muscles elevate the mandible and what cavity does it occur in
temporalis, masseter, medial pterygoid, inferior cavity
what depresses the mandible and what cavity does it occur in
gravity, suprahyoid, infrahyoid, lateral pterygoid, inferior cavity
how do the infrahyoids contribute to the depression of the mandible
they fix/move the hyoid bone to allow suprahyoids to depress the mouth
what muscles allow lateral (chewing) movements
temporalis on same side and pterygoids on opposite side
when there is no movement, what position is the mandible in
heads in retracted position in mandibular fossa and chin elevated by tone of retractors and elevators
what are the gliding movements
protrusion and retraction
what happens during dislocation
the mandible slips forward to articular tubercle but slips too far
why does dislocation happen
excessive contraction of lateral pterygoids (either yawning/large bite) or a sideways blow to the chin whilst mouth is open
what happens once the mandible is dislocated
it remains in a depressed position and cannot close
what nerves are of close relationship to the TMJ
facial and auriculotemporal nerves
what nerve overlies the TMJ
facial nerve
what nerves supply the TMJ
articular branches of the auriculotemporal nerve
how do the articular branches of the auriculotemporal nerve get damaged
trauma and rupture of articular capsule or due to surgery
what happens if the articular branches of the auriculotemporal nerve get damaged
the jaw is even more lax and unstable
what are the muscles of mastication supplied by
CNV3
what is the origin and insertion of the temporalis
origin - temporal fossa and fascia
insertion - coronoid process of mandible and anterior border of ramus of mandible near last molar
what is the function of the temporalis
retracts and elevates mandible
what is the temporalis innervated by
deep temporal nerves from anterior trunk of CNV3
what is the origin and insertion of the masseter
origin - maxillary process of zygomatic bone and anterior 2/3rd of inferior border of zygomatic arch
insertion - angle of lateral surface of ramus of mandible
what is the function of the masseter
elevation of the mandible
what is the masseter innervated by
masseteric nerve from anterior trunk of CNV3
what is the origin and insertion of the medial pterygoid
origin - medial surface of lateral pterygoid plate and maxillary tuberosity and pyramidal process of palatine bone
insertion - medial surface of ramus and angle of mandible
what is the action of the medial pterygoid
elevates mandible and assists with lateral movements
what is the innervation of the medial pterygoid
nerve to medial pterygoid from main trunk of CNV3
what is the clinical relevance of the medial pterygoid
when giving an IDB the needle can pierce the medial pterygoid and cause trismus
what is the origin and insertion of the lateral pterygoid
origin - infratemporal surface of greater wing of sphenoid bone and lateral surface of lateral pterygoid plate
insertion - front of neck of mandible
what is the action of the lateral pterygoid
protrudes mandible, assists medial pterygoid with lateral side to side movements and depresses mandible
what is the innervation of the lateral pterygoid
nerve to medial pterygoid and buccal nerve from anterior trunk CNV3
