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Module 2 > Oral Biology: Muscles of Mastication > Flashcards

Oral Biology: Muscles of Mastication Flashcards

1
Q

What does “mastication” mean?

A

Chewing

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2
Q

What does the breakdown of food stuffs via mastication involve? (3)

A

1) preparation for swallowing
2) increase surface area for chemical digestion
3) release of chemicals for sense of taste

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3
Q

What is stimulated by mastication?

A

salivary flow

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4
Q

Where do masticatory movements take place?

A

The temporomandibular joint (TMJ)

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5
Q

What does the TMJ comprise of?

A

1) Glenoid Fossa of the Temporal Bone
2) Articular Eminence
3) Condyle of the Mandible

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6
Q

What movement occurs at the TMJ with a slight jaw opening?

A

A simple hinge movement

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7
Q

What movement occurs at the TMJ with a wide jaw opening?

A

Hinge and Slide

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8
Q

What movement occurs at the TMJ when the jaw protrudes?

A

Slide movement

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9
Q

What three groups of muscles are involved in mastication?

A

1) Muscles between the skull and mandible
2) muscles between mandible and hyoid
3) hyoid stabilisers

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10
Q

What group of muscles acts across the TMJ and is considered the main group of muscles of mastication?

A

Muscles between the skull and the mandible

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11
Q

Name the four muscles under the “Skull-Mandible” group

A

1) Masseter
2) Temporalis
3) Medial Pterygoid
4) Lateral Pterygoid

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12
Q

What is the:

1) origin
2) insertion

of the SUPERFICIAL MASSETER?

A

1) Origin: zygomatic arch/bone

2) Insertion: angle/ramus of the mandible

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13
Q

What is the action of the superficial masseter muscle?

A

Jaw elevation (closing), minor protrusive action

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14
Q

What nerve innervates the superficial masseter?

A

Masseteric nerve of the Motor Root of CNVc

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15
Q

What is the:

1) origin
2) insertion

of the DEEP MASSETER?

A

1) Origin: Inner aspect of the zygomatic arch

2) Insertion: angle/ramus of the mandible

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16
Q

What is the action of the deep masseter muscle?

A

Jaw elevation (closing)

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17
Q

What is the innervation of the deep masseter muscle?

A

Masseteric nerve of the motor root of CNVc

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18
Q

What is the:

1) origin
2) insertion

of the TEMPORALIS?

A

1) Origin: inferior temporal line and fascia

2) Insertion: coronoid process

19
Q

What is the action of the Temporalis muscle?

A

Jaw elevation and retrusion (due to it’s posterior fibres)

20
Q

What innervates the Temporalis muscle?

A

Deep Temporal Nerve of the Motor Root of CNVc

21
Q

What is the:

1) origin
2) insertion

of the UPPER HEAD of the LATERAL PTERYGOID?

A

1) Origin: Infratemporal surface of the greater wing of sphenoid
2) Insertion: capsule and articular disc of TMJ

22
Q

What is the:

1) origin
2) insertion

of the LOWER HEAD of the LATERAL PTERYGOID?

A

1) Origin: lateral aspect of the lateral pterygoid plate

2) Insertion: pterygoid fovea below head of condyle

23
Q

What is the action of the lateral pterygoid?

A

A complex action which ultimately leads to jaw opening.
Initial opening: hinge in lower joint space with help from suprahyoids only.
Wide opening: anterior and inferior translation of condyle assisted by inferior lateral pterygoids

24
Q

What innervates the lateral pterygoid?

A

CNVc motor root - nerve to lateral pterygoid

25
Q

What does the inferior head of the lateral pterygoid do:

1) bilaterally?
2) unilaterally?

A

Bilaterally:

1) pulls condyle forward
2) assists opening
3) protrusion

Unilaterally:
1) facilitates lateral excursion

26
Q

When is the superior head of the lateral pterygoid active?

A

During retrusion and closing

27
Q

What is the:

1) origin
2) insertion

of the MEDIAL PTERYGOID?

A

1) Origin: medial aspect of lateral pterygoid plate of the sphenoid bone and maxillary tuberosity
1) Insertion: Medial aspect of ramus/angle of the mandible

28
Q

What is the action of the medial pterygoid? (2)

A

1) jaw elevation

2) assists protrusion and lateral excursions (unilateral)

29
Q

What innervates the medial pterygoid muscle?

A

CNVc Motor Root - nerve to medial pterygoid

30
Q

What are the three muscles that fall under the Mandible-Hyoid group?

A

1) Geniohyoid
2) Mylohyoid
3) Digastric (anterior)

31
Q

What is the:

1) origin
2) insertion

of the geniohyoid muscle?

A

1) Origin: inferior mental spine and inferior genial tubercle
2) Insertion: Hyoid bone

32
Q

What is the action of the geniohyoid muscle when:

1) the hyoid is fixed
2) the hyoid is not fixed

A

1) hyoid fixed: jaw opening (and retrusion)

2) hyoid not fixed: raise (and forward) hyoid

33
Q

What innervates the geniohyoid muscle?

A

C1 spinal nerve (with hypoglossal)

34
Q

What is the:

1) origin
2) insertion

of the MYLOHYOID muscle?

A

1) Origin: mylohyoid line of the mandible

2) upper border of the hyoid bone

35
Q

What innervates the mylohyoid muscle?

A

CNVc Motor Root - nerve to mylohyoid

36
Q

What is the raphe that lies inferiorly to the mylohyoid muscle called?

A

the median raphe

37
Q

What is the action of the MYLOHYOID muscle when:

1) hyoid is fixed?
2) hyoid is not fixed?

A

1) Hyoid Fixed: jaw opening

2) Hyoid not fixed: raise hyoid and floor of mouth

38
Q

What is the:

1) origin
2) insertion

of the anterior belly of digastric?

A

1) Origin: Digastric Fossa of the mandible

2) Insertion: intermediate tendon (secured to the hyoid bone by a fibrous loop

39
Q

What is the action of the anterior belly of digastric when:

1) hyoid is fixed
2) hyoid is not fixed

A

1) Hyoid fixed: jaw opening

2) Hyoid not fixed: raise hyoid

40
Q

What innervates the anterior belly of digastric?

A

CNVc Motor Root - via nerve to mylohyoid

41
Q

What are the three muscles that fall under the “Hyoid Stabliser” group?

A

1) Infrahyoids (thyrohyoid, omohyoid, sternohyoid)
2) Posterior Digastric
3) Stylohyoid

42
Q

What other two muscles are involved in mastication?

A

1) obicularis oris (oral sphincter)

2) buccinator (along with the tongue, helps control the bolus of food and direct it to posterior teeth)

43
Q

What are the physiological chewing forces (N) in:

1) dentate patients?
2) edentulous patients?

A

1) dentate patients: 70-150N

2) edentulous patients: 4-55N

44
Q

What is the maximum clenching force between molars (N)?

A

500-700N

Module 2 (6 decks)

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