Occlusion I - Ligaments and Muscles of Mastication

What are the functional ligaments of the TMJ region?

collateral, capsular, temporomandibular

What are the accessory ligaments of the TMJ region?

sphenomandibular, stylomandibular

What is the function of the collateral ligaments?

restricts movement of disc away from condyle

What is the function of the capsular ligaments?

- encompasses TMJ

- resist forces that may separate/dislocate articular surfaces

- retains synovial fluid

What is the function of the temporomandibular ligaments?

- IHP: limits posterior movement

- OOP: resists excessive dropping limits mouth opening

What is the origin and insertion of the masseter?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

C) origin - pterygoid fossa / insertion - medial surface of mandibular angle

D) origin - lateral pterygoid plate / insertion - neck of condyle

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

What is the function of the masseter?

elevates mandible

What is the origin and insertion of the temporalis?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

C) origin - pterygoid fossa / insertion - medial surface of mandibular angle

D) origin - lateral pterygoid plate / insertion - neck of condyle

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

What is the function of the temporalis?

elevates mandible

What is the origin and insertion of the medial pterygoid muscle?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

C) origin - pterygoid fossa / insertion - medial surface of mandibular angle

D) origin - lateral pterygoid plate / insertion - neck of condyle

C) origin - pterygoid fossa / insertion - medial surface of mandibular surface

What is the origin and insertion of the inferior lateral pterygoid muscle?

A) A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

C) origin - pterygoid fossa / insertion - medial surface of mandibular angle

D) origin - lateral pterygoid plate / insertion - neck of condyle

D) origin - lateral pterygoid plate / insertion - neck of condyle

What is the origin and insertion of the superior lateral pterygoid plate?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - zygomatic arch / insertion - 2nd molar to mandibular angle

C) origin - infratemporal surface of greater sphenoid wing / origin - articular capsule, disc, neck of condyle

D) origin - lateral pterygoid plate / insertion - neck of condyle

C) origin - infratemporal surface of greater sphenoid wing / origin - articular capsule, disc, neck of condyle

What is the function of the medial pterygoid?

- elevates + protrudes mandible

- unilateral --> mediotrusive movement

What is the function of the inferior lateral pterygoid muscle?

protrudes mandible

What is the function of the superior lateral pterygoid muscle?

especially active during power stroke

What is the origin and insertion of the anterior belly of the digastric?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - mastoid notch / insertion - intermediate tendon attached to hyoid bone

C) origin - fossa on lingual surface of mandible / insertion - intermediate tendon attached to hyoid bone

D) origin - lateral pterygoid plate / insertion - neck of condyle

C) origin - fossa on lingual surface of mandible / insertion - intermediate tendon attached to hyoid bone

What is the origin and insertion of the posterior belly of the digastric?

A) origin - temporal fossa + lateral surface of skull / insertion - coronoid process + anterior border of ascending ramus

B) origin - mastoid notch / insertion - intermediate tendon attached to hyoid bone

C) origin - fossa on lingual surface of mandible / insertion - intermediate tendon attached to hyoid bone

D) origin - lateral pterygoid plate / insertion - neck of condyle

B) origin - mastoid notch / insertion - intermediate tendon attached to hyoid bone

What is the function of the digastric muscle?

depressed mandible and raises hyoid bone

What are the main muscles of mastication?

masseter, temporalis, medial pterygoid, and lateral pterygoid

What are the 2 distinct systems of the TMJ?

1) condyle-disc system that surrounds inferior synovial cavity (responsible for rotational movement of TMJ)

2) condyle-disc system functioning against mandibular fossa

(occurs when mandibular moves forward)

True/False: muscles of mastication are in a mild state of tonus

True

What occurs with disc space when pressure is decreased in the interarticular space?

decrease in pressure = disc space widens

What occurs with disc space when pressure is increased in the interarticular space?

increase in pressure = disc space narrows

What helps maintain the constant contact of the articular surfaces of the TMJ?

muscles of mastication