Lecture 8: TMJ Joint Final?

Question 1

Key considerations for mastication

Answer 1

involves chewing, tearing, teeth grinding, speaking, and swallowing

interaction between CNS and muscles

TMJ = one of the most used joints of the body

Question 2

bones involved in mastication

Answer 2

mandible
maxilla
temporal bone
sphenoid bone
hyoid bone

Question 3

where can you palpate the mandibular condyle

Answer 3

just anterior to the external auditory meatus

Question 4

what is the temporal fossa

Answer 4

slightly concave region

formed by parietal, temporal, frontal, sphenoid, and zygomatic bones

attachment for temporalis muscle

Question 5

describe characteristics of the mandible

Answer 5

largest of facial bones
very mobile
suspended by ligaments/capsule and muscles
many landmarks

Question 6

describe characteristics of the maxilla

Answer 6

R and L sides fuse
it is fixed
forms the floor of nasal cavity and the orbit of the eyes

Question 7

key considerations for the sphenoid bone

Answer 7

it does not contribute to the TMJ structure

it does provide proximal attachments for medial and lateral pterygoid muscles

Question 8

hyoid bone is anterior to what

Answer 8

C3

Question 9

describe the osseous structures of the TMJ joint

Answer 9

flattened front to back (condyle) thin dense layer of fibrocartilage (better at absorbing force than hyaline with superior reparative process)

medial and lateral poles

Question 10

describe the mandibular fossa

Answer 10

it is articular (sloped anterior wall), load bearing, thin/compact bone, and lined with fibrocartilage

full opening - they condyle slides forward (~50 degrees) across this opening with shear and compression forces

superior and posterior areas are non-articular, thin, and non load bearing

Question 11

capsular structures in the TMJ joint

Answer 11

loose fibrous capsule
synovial membrane
capsule is firm medially/laterlaly and provides support

lax anterior to posterior to allow mouth opening

Question 12

ligamentous estrutures of the TMJ joint

Answer 12

lateral ligaments stabilize

have oblique and horizontal fibers

Question 13

what osteokinematics take place at the TMJ joint

Answer 13

protrusion: mandible translates anterior without rotation
recursion: reverse

lateral excursion: side to side (contralateral and ipsilateral); average 11mm max unilateral

depression and elevation: avg opens about 45-50 mm; typical mastication is 18mm

Question 14

describe the arthrokinematics of the TMJ joint

Answer 14

combo of rotation and translation

rotation: mandibular condyle rotates relative to the inferior surface of the disc

translation: the mandibular condyle and disc slide together

Question 15

what arthrokinematics take place in the TMJ joint with protrusion and retrusion

Answer 15

mandibular condyle and disc translate anterior/posterior

1.25 max

follows the slope of articular prominence (i.e. protrusion = anterior and downward)

Question 16

describe the arthrokinematics of the TMJ joint with lateral excursion

Answer 16

side to side translation

mandibular condyle on the lateral excursion serves as a pivot point with contralateral condyle making a wider arc of rotation

Question 17

describe the arthrokinematics of the TMJ joint with depression and elevation

Answer 17

combo of rotation and translation
axis is constantly moving
no set radio of rotation/translation

early and late phase movements

Question 18

describe the arthrokinematics of the TMJ joint with depression and elevation

Answer 18

combo of rotation and translation
axis is constantly moving
no set radio of rotation/translation

early and late phase movementsdesci

Question 19

describe the arthrokinematics of the TMJ joint doing the early phase of depression/elevation

Answer 19

35-50% primarily rotation

posterior rotation on concave inferior surface of the disc

mandible goes inferior/posterior

Question 20

describe the arthrokinematics of the TMJ joint during the late phase of depression/elevation

Answer 20

final 50-65%

primarily translation (1.5-2mm)

condyle and disc slide forward and inferior along the articular eminence

closing is reverse (tension in retrodiscal lamina helps)

Question 21

innervation of the muscles of the TMJ joint

Answer 21

primary muscles = mandibular nerve (division of the trigeminal nerve- CN V)

sensory is from 2 branches of the mandibular nerve

Question 22

what are the primary muscles of mastication

Answer 22

masseter
temporalis
medial pterygoid
lateral pterygoid

Question 23

describe the masseter

Answer 23

thick, strong,
zygomatic arch to ramus of mandible,
line of force is perpendicular
large forces to crush food

Question 24

describe the temporalis muscle

Answer 24

flat fan shaped
through space to anterior and medial ramus
elevates

Question 25

describe the medial pterygoid

Answer 25

nearly parallel to the masseter

internal surface of ramus

bilateral elevation and unilateral/contralateral excursion

Question 26

describe the lateral pterygoid

Answer 26

2 heads

travels horizontally

unilateral is contralateral excursion

bilateral strong protrusion

Question 27

max human biting force

Answer 27

422 N (95 lbs)

Question 28

what are the secondary muscles of mastication

Answer 28

supra hyoid: can assist with depression of mandible, speech/tongue movement, swallowing, and managing food bolus

infra hyoid: stabilizes

Question 29

describe TMJ disorders

Answer 29

broad and vague
impairment of muscles, joints, ligaments, and discs
often from teeth grinding or FHP (and sometimes OA)
most cases are self limiting

Question 30

what are signs and symptoms of TMJ disorders

Answer 30

popping
reduced bite force
reduced open range
locking
headaches
tinnitus
facial/scalp pain