Axial skeleton Flashcards

1
Q

What is the axial skeleton?

A

the portion of the skeletal system that is on the longitudinal axis of the body (runs down the center of gravity)

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2
Q

What are the 6 major components of the axial skeleton?

A

skull
notochord
hyoid (hyobranchial) apparatus
ribs
sternum
vertebral column

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3
Q

What are the major functions of the axial skeleton?

A

act as a framework to support and protect organs

provide a surface for muscle attachments including:
- neck, head, trunk
- respiration
- appendicular skeleton

involved in body movement (works with appendicular skeleton and muscles)

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4
Q

Joints of the axial skeleton are heavily reinforced with what to allow for restricted movement?

A

ligaments

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5
Q

T or F: axial bones are weak

A

false, they are very strong

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6
Q

what is the function of the notochord?

A

provided early vertebrates with non-bony support to allow swimming via lateral movement of spine

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7
Q

Describe the notochord

A

made of vacuolated cells covered by a fibrous and thick sheath

rigid, but also laterally flexible

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8
Q

Where is the notochord located within the body plan?

A

ventral and parallel to the dorsal hollow nerve cord

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9
Q

In what life stages is the notochord present?

A

larval urochordates: present in tail

cephalochordates and vertebrates: present in body and tail

embryo of all vertebrates but may be very reduced in adult

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10
Q

In vertebrates which lose or reduce the notochord in adulthood, what replaces it?

A

the vertebral column

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11
Q

What is the hyoid/hyobranchial apparatus?

A

group of visceral arches supporting the tongue and larynx in tetrapods

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12
Q

What are the functions of ribs and sternum in tetrapods?

A

protect the lungs and heart

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13
Q

Are ribs flexible or rigid? why?

A

flexible, in order to allow the lungs to expand for breathing

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14
Q

Describe the structure of ribs

A

thin
flexible
light
but strong enough to have chest muscles attached

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15
Q

Why must the ribs be thin and light?

A

in order to be flexible to allow lung expansion

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16
Q

What muscles attach to the ribs?

A

chest muslces

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17
Q

what do the chest muscles do?

A

support upper body and forelimbs

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18
Q

What do most of the ribs attach to at their medial (middle) ends?

A

the sternum via bridges of flexible cartilage

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19
Q

How is the sternum modified in amphibians?

A

except for frogs, the sternum is made of cartilage

frogs have cartilage and bone

it is attached to the pectoral girdle only - not to any ribs

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20
Q

What is the sternum attached to in amphibians?

A

the pectoral girdle, not ribs

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21
Q

How is the sternum modified in reptiles such as alligators and lizards?

A

sternum is cartilaginous

attached to ribs

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22
Q

What is the sternum attached to in alligators and lizards?

A

ribs

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23
Q

How is the sternum modified in reptiles such as snakes and turtles?

A

it is absent in both, but replaced by plastron in turtles

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24
Q

How is the sternum modified in flying birds?

A

one large body element articulating with the ribs

contains a strong central keel where flight muscles attach

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25
what is the sternum attached to in flying birds?
multiple ribs and flight muscles
26
How is the sternum modified in mammals? what is it attached to?
it is composed of multiple bones attached to ribs via costal cartilages
27
What are the individual units of the vertebral column?
vertebra
28
What are the basic units of an individual vertebra?
vertebral/neural arch hemal arch neural spine centrum transverse process zygapophysis intervertebral disks
29
What are the 5 regions of the vertebral column?
cervical (atlas and axis) thoracic lumbar sacral caudal
30
Where are the cervical vertebrae?
neck vertebrae (absent in fish), directly under the skull atlas: the first cervical vertebra in terrestrial vertebrates axis: the second cervical vertebra of mammals
31
What is the function of the atlas vertebra?
articulates with the skull and allows nodding movements of the head
32
What is the function of the axis vertebra?
allows rotation of the head
33
Which vertebrates lack the cervical vertebrae?
fish (think about how fish do not have a distinct head that can be moved around up and down and rotated)
34
which order, from the skull, do the cervical vertebrae arise? (if present)
atlas is the first vertebra - articulates with the skull axis is the second vertebra
35
Where are the thoracic vertebrae?
in the chest region these articulate with the ribs
36
What do the thoracic vertebrae articulate with?
the ribs
37
where are the lumbar vertebrae found?
the lower back
38
Where are the sacral vertebrae found?>
lower than the lower lumbar vertebrae
39
What is unique about the sacral vertebrae?
they are fused = called the sacrum
40
How many sacral vertebrae are fused in dogs and cats to create the sacrum? how about humans?
dogs and cats have 3 fused vertebrae making up the sacrum humans have 5
41
Where are the caudal vertebrae?
the tail vertebrae
42
In birds, what forms the attachment for tail feathers to the caudal vertebrae?
the pygostyle
43
How many vertebral regions do fish have? what are they?
2 trunk and caudal
44
How many vertebral regions do amphibians have? what are they?
4 cervical, trunk, sacral, caudal except anurans (tailless), which lack the caudal
45
Compare the vertebral regions of frogs and salamanders
both have cervical, trunk and sacral vertebrae regions frogs do not have caudal
46
How many vertebral regions do non-bird reptiles have? what are they?
5 cervical, thoracic, lumbar, sacral, caudal
47
How many vertebral regions do birds have? what are they?
5 cervical, thoracic, lumbar, sacral, caudal
48
How many vertebral regions do mammals have? what are they?
5 cervical, thoracic, lumbar, sacral, caudal (or coccyx in mammals without tails)
49
Which vertebrate group(s) have trunk vertebrae?
fish and amphibians
50
Which vertebrate group is the only one that lacks cervical vertebrae?
fish
51
What are the major functions of the vertebral column?
enclose and protect spinal cord structural support allows for movement of head points of attachment for ribs and muscles
52
Similarities and differences between axial skeleton of fish and amphibians?
similarities: - both have trunk and caudal (anurans do not though) vertebrae differences: fish only have 2 vertebral regions (trunk and caudal) amphibians have 3-4 (cervical, trunk, sacral, and some have caudal)
53
Differences between axial skeleton of fish and reptiles?
similarities: - both have caudal vertebrae differences: fish have 2 vertebral regions (trunk, caudal) reptiles have 5 vertebral regions (cervical, thoracic, lumbar, sacral, caudal) fish do not have neck vertebrae reptiles have more diversity in their axial skeleton
54
Differences between axial skeleton of fish and birds?
birds have 5 vertebral regions, fish have 2 birds have a lot of fused vertebrae = rigid vertebral column, fish have much more flexible vertebral column for lateral movement
55
Differences between axial skeleton of fish and mammals?
mammals have 5 vertebral regions, fish have 2
56
Differences between axial skeleton of amphibians and non-bird reptiles?
amphibians have 4 vertebral columns, reptiles have 5 both have: cervical, sacral, and caudal amphibians also have trunk reptiles lack trunk, but also have lumbar and thoracic
57
Differences between axial skeleton of amphibians and birds?
amphibians have 4 vertebral columns, birds have 5 both have: cervical, sacral, and caudal amphibians also have trunk birds lack trunk, but also have lumbar and thoracic birds also have pygostyle in caudal region
58
Differences between axial skeleton of amphibians and mammals?
amphibians have 4 vertebral columns, mammals have 5 both have: cervical, sacral, and caudal amphibians also have trunk mammals lack trunk, but also have lumbar and thoracic mammals have a fused sacrum
59
Differences between axial skeleton of non-bird reptiles and birds?
they have the same 5 regions (cervical, thoracic, lumbar, sacral, caudal) birds have pygostyles to attach tail feathers to caudal vertebrae, whereas nonbird reptiles do not birds have very rigid vertebral column, many vertebrae are fused
60
Differences between axial skeleton of non-bird reptiles and mammals?
reptiles do not have spinal curves mammals have thoracic and sacral curves during fetal development after birth, mammals have lumbar and cervical curves (these allow for upright positions)
61
Differences between axial skeleton of birds and mammals?
birds have 5 thoracic vertebrae, 4 of which are fused all thoracic vertebrae in mammals are attached to a pair of ribs
62
What allows the upright position in mammals?
the appearance of secondary curves (lumbar and cervical curves) after birth allows the shift of body weight
63
What are the primary spinal curves in mammals?
thoracic and sacral because they are present during fetal development and accommodate internal organs
64
What is the function of primary spinal curves in mammals?
to support and protect the internal organs during fetal development thoracic and sacral
65
what is the function of secondary spinal curves in mammals?
to compensate for shifting body weight to allow for an upright posture cervical and lumbar