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Anatomy II Exam 1: Lectures 1-8 > Lecture 5: Jaws And Teeth > Flashcards

Lecture 5: Jaws And Teeth Flashcards

1
Q

Describe the relative size and position of the temporalis muscle in humans vs. chimps

A

Smaller in humans

More muscle on medial side in chimps

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2
Q

Describe the possible and impossible range of mandibular excursion

A

The lateral view of the temporalis suggests 30 mm of movement, but the bipennate structure only permits 15 mm

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3
Q

Compare the masseter muscle in humans vs. other primates

A

In primates it is much larger and more complex - they have superficial and deep component

It is multipennate in both so there is not a lot of movement but it is very strong

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4
Q

Of the muscles of mastication: medial and lateral pterygoid, which has dual heads?

A

Lateral pterygoid

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5
Q

True or false: the medial pterygoid is multipennate

A

True

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6
Q

The lower head of the lateral pterygoid acts as a ________________ ______________

A

Protruder depressor

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7
Q

In terms of the depressors of the jaw or elevators of the hyoid, the _____________ is associated with the jaw and the ___________ is associated with the chin

A

Mylohyoid

Geniohyoid

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8
Q

The ______ and ______ hyoid muscles can both depress the jaw and elevate and protrude the hyoid bone

A

Supra

Infra

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9
Q

It is important to note that jaws don’t just hinge, they also protrude. Excursion happens onto __________ _________. Condyle rotates AND slides forward onto this structure and takes __________ ________ with it. As a result, the jaw drops down and forward with full mouth opening

A

Articular eminence

Articular disc

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10
Q

What muscle allows the excursion of the condyle of the mandible?

A

Lateral pterygoid

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11
Q

The temporalis elevates the mandible with its _____________ fibers.

It retracts the protruded mandible with its ____________ ___________ fibers.

___________ __________: mastication that moves the mandibular head on the balance side forward

A

Vertical

Horizontal posterior

Unilateral contraction

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12
Q

The masseter ______ and ______ the mandible

A

Elevates and protrudes

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13
Q

The medial pterygoid ________ the mandible

A

Elevates

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14
Q

___________ ____________ of the lateral pterygoid: initiates mouth by ___________ the mandible and moving the articular disk forward.

____________ __________ of the lateral pterygoid: ________ the mandible to the opposite side during mastication

A

Bilateral contraction; protruding

Unilateral contraction; elevates

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15
Q

What are the glenoid variations among hominids?

A

Medial translation
Medial excursion

In Parathropus boisei

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16
Q

What are the types of mandibular strain?

A

Symphysial shear and compression

Twisting and bending of corpora

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17
Q

During __________ mandibular strain, it is counteracted with __________ symphyseal height

A

Shear; greater

18
Q

________________ during “wishboning” in mandibular strain is counteracted with ___________ symphyseal AP depth

A

Compression; Greater

19
Q

During ___________ mandibular strain, it is counteracted with __________ corpus breadth

A

Twisting; Greater

20
Q

During ____________ mandibular strain, it is counteracted with _________ corpus height

A

Bending; Greater

21
Q

Describe the structures of TMJ when chewing

A

The horizontal band is taut on the working side after balancing side excursion during chewing

22
Q

What happens to the center of rotation during TMJ excursion?

A

Articular disc drops vertically when fully abducted

23
Q

Compare the symphyseal anatomy of the mandible between humans, orangutan and A. afarensis

A

Humans and orangutan have simian shelf to reinforce bone on jaw
A. Afarensis does not have a simian shelf

24
Q

Compare the hominid corpora and the size of the mandible

A

Overall size of mandible is reflected by cross sectional area
In overall build, the mandibles of Homo are less robust than those of other hominids

25
Q

Compare the shape and size of the hominin mandible and teeth between males and females in A. afarensis

A

In females: have smaller mandible and the last molar lies wide of the dental arcade and creates the v shaped arch
In males: posterior teeth form straight rows and dental arch is narrow

26
Q

To avoid discussion of TMJ the ________ of all muscle force vectors must stay within a triangle of support

A

Resultant

27
Q

The jaw is actually two ______ class levers attached _______

A

third; anteriorly

28
Q

The jaw moves ______ if the amount of force does not _______ on the balancing side when biting

A

out; decrease

29
Q

What is the adult dental formula?

A

2.1.2.3/2.1.2.3

30
Q

What is the deciduous dental formula?

A

2.1.0.2/2.1.0.2

31
Q

True or false:

You can still make enamel after it emerges from the mandible.

A

False

Ameloblasts and odontoblasts make enamel shape in the mandible and emerges. Cannot make more enamel

32
Q

What is the purpose of the interlocking enamel prisms?

A

Increase toughness of enamel

33
Q

Describe the dentition and diet of fruit eaters

A

Broad incisors
Low rounded molar cusps
Long small intestine

34
Q

Describe the dentition and diet of leaf eaters

A

Small incisors
Developed molar crests for shearing and grinding
Complex stomach or enlarged large intestine

35
Q

Describe the dentition and diet of insect eaters

A

Sharp cusps

Short, simple gut

36
Q

What is the pattern of hominin molars?

A

5Y pattern in lower molar

37
Q

What is the relationship between molars and bite force in hominins?

A

The bigger the molar teeth, the harder you can bite

38
Q

How can shearing efficiency improve in hominins?

A

Through wear

39
Q

What does it appear the wear was due to in neanderthals?

A

Para masticatory behavior

40
Q

What are some hominin characteristics of dentition?

A
  1. Thick enamel layer
  2. Modified keyhole pattern of enamel points
  3. Anterior dentition reduced in size
  4. Canines wear at tip
  5. All premolars bicuspid
  6. Molars greatly enlarged in early hominids
41
Q

What is the dental arcade shaped like in hominins?

A

Parabolic in shape

42
Q

Describe the hominin characteristics of the human skull

A
  1. Chewing involved significant lateral motions of the mandible
  2. Expansion of the brain and braincase

Anatomy II Exam 1: Lectures 1-8 (10 decks)

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