TMJ and Muscles of Mastication

Question 1

what is the function of the condylar process

Answer 1

its the articular process of the TMJ

Question 2

where does the nerve and vessels to the masseter muscle pass through on the mandible

Answer 2

the mandibular notch

Question 3

what is the mandibular symphis

Answer 3

where the two halves of the mandible have fused

Question 4

where is the IAN and its associated artery and vein housed

Answer 4

mandibular foramen

Question 5

what is the relevance of the mylohyoid line with regards to infections and what condition can this cause

Answer 5

infections in lower teeth may spread to below mylohyoid line and into flood of the mouth and submandibular region (LUDWIG’S ANGINA)

Question 6

where does the nerve to the mylohyoid branch off from the IAN

Answer 6

the mylohyoid groove

Question 7

what comprises the TMJ

Answer 7

the mandibular fossa of temporal bone and condylar process of mandible

Question 8

what type of joint is the TMJ

Answer 8

a modified hinge (atypical) synovial joint

Question 9

what are the articular surfaces of the TMJ covered with

Answer 9

fibrocartilage

Question 10

what type of dislocation in the TMJ is most common

Answer 10

anterior

Question 11

how many ligaments are in the TMJ

Answer 11

3 (2 extrinsic and 1 intrinsic)

Question 12

what are the functions of the TMJ ligaments

Answer 12

connect mandible to cranium

Question 13

what are the two extrinsic ligaments

Answer 13

sphenomandibular and stylomandibular

Question 14

what ligament provides passive support to the mandible and runs from the spine of sphenoid to the lingula

Answer 14

sphenomandibular ligament

Question 15

what ligament is a thickening of the capsule of the parotid and runs from the styloid process to angle of the mandible and is not consider to contribute to strength

Answer 15

stylomandibular ligament

Question 16

what is the function of the lateral ligament

Answer 16

strengthens TMJ laterally

Question 17

how many types of movements can the mandible produce and what are they

Answer 17

5 - protrusion, retraction, elevation, depression and lateral

Question 18

what muscles aid the protrusion of the mandible

Answer 18

lateral pterygoid and medial pterygoid

Question 19

what are protrusive and retractive movements

Answer 19

gliding movement between temporal bone and articular disc

Question 20

what muscles aid in retraction of the mandible

Answer 20

posterior fibres of temporalis, deep part of masseter and geniohyoid and digastric

Question 21

what muscles aid in elevation of the mandible

Answer 21

temporalis, masseter and medial pterygoid

Question 22

what muscles aid in depression of the mandible

Answer 22

digastric, geniohyoid and mylohyoid

Question 23

what are elevation/ depression movements

Answer 23

hinge and rotational movements between head of mandible and articular disc

Question 24

what are lateral movements and what muscles aid in this

Answer 24

grinding and chewing and this is aided by temporalis on the same side and pterygoids on opposite side

Question 25

when is TMJ most unstable

Answer 25

during depression as the condylar process moves anteriorly and lies under the articular eminences with mandibular head vulnerable to anterior dislocation

Question 26

what is the position of the mandible at rest

Answer 26

the heads of mandible are held in a retracted position in the mandibular fossae and chin is elevated by tonus of the retractors and elevators of mandible

Question 27

how does anterior dislocation of the mandible occur

Answer 27

through excessive contraction of lateral pterygoids through yawning (or sometimes a punch to the chin when the mouth is open)

Question 28

what occurs when the TMJ is dislocated

Answer 28

the mandible remains depressed and the person cant close their mouth

Question 29

why is posterior dislocation uncommon

Answer 29

it is resisted by postglenoid tubercle and strong intrinsic lateral ligament

Question 30

what occurs when there is injury to the articular branches of auriculotemporal nerve supplying the TMJ

Answer 30

laxity and instability of TMJ

Question 31

what muscles are involved in elevation of mandible

Answer 31

temporalis, masseter and medial pterygoid

Question 32

what muscles are involved in depression of the mandible

Answer 32

lateral pterygoid, suprahyoid and infrahyoid muscles

Question 33

what muscles are involved in protrusion of the mandible

Answer 33

lateral pterygoid, masseter and medial pterygoid

Question 34

what muscles are involved in retrusion of the mandible

Answer 34

temporalis

Question 35

what pharyngeal arch are the muscles of mastication derived from

Answer 35

first pharyngeal arch

Question 36

what is the origin and insertion of the temporalis

Answer 36

O = temporal fossa and fascia I = coronoid process of mandible and anterior border of ramus

Question 37

what is temporalis innervated by

Answer 37

deep temporal nerves from anterior trunk of CN V3

Question 38

what is the origin and insertion of the superficial part of the masseter

Answer 38

O = maxillary process of zygomatic bone and anterior 2/3rd of inferior border of zygomatic arch I = angle and lateral surface of ramus of mandible

Question 39

what is the masseter innervated by

Answer 39

masseteric nerve from anterior trunk of CN V3

Question 40

what is origin and insertion points of the superficial head of the medial pterygoid

Answer 40

O = maxillary tuberosity and pyramidal process of palatine bone I = angle of mandible

Question 41

what is the origin and insertion points of the deep head of the medial pterygoid

Answer 41

O = medial surface of lateral pterygoid plate I = medial surface of ramus

Question 42

what is the medial pterygoid innervated by

Answer 42

nerve to the medial ptergoid from main trunk of CN V3

Question 43

what is the origin and insertion point of the upper head of lateral ptergoid

Answer 43

O = infratemporal surface of greater wing of sphenoid bone I = capsule of TMJ and articular disc

Question 44

what is the origin and insertion points of the lower head of the lateral pterygoid

Answer 44

O = lateral surface of lateral pterygoid plate I = front of the neck of the mandible (pterygoid fovea)

Question 45

in relation to muscles of mastication, what can cause trismus

Answer 45

an IAN block piercing the medial pterygoid causing it to contract reflexively and close the mouth

Question 46

what is the lateral pterygoid innervated by

Answer 46

nerve to the lateral pterygoid and buccal nerve from anterior trunk of CN V3