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Comparative Anatomy > Skeletal System 1: The Axial Skeleton > Flashcards

Skeletal System 1: The Axial Skeleton Flashcards

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1
Q

What are vertebrates a subphylum of?

A

Vertebrates are a subphylum within the Chordate phylum

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2
Q

What are the features of a chordate?

A
  1. Pharyngeal slits
  2. Notochord
  3. Dorsal hollow nerve tube
  4. Endostyle (–> thyroid gland)
  5. Post-anal tail
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3
Q

What is an overview of the axial skeleton?

A

Vertebral column

Ribs and sternum

Head

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4
Q

What is the function of the vertebral column: Cervicals?

A

Support/articulate head

Protect spinal cord

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5
Q

What is the function of the vertebral column: Thoracic vertebrae?

A

Anchorage for muscles and ligaments
(locomotion/weight support)

Flexibility for locomotion

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6
Q

What is the function of the vertebral column: Lumbars/Sacrals?

A

Conduct forces from limbs for locomotion/weight support

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7
Q

What are the individual parts of the Axial skeleton?

A

Cervicals
- Cervical ribs

Thoracic vertebrae
- Thoracic ribs
- Gastralia

Sternum
Interclavicle
Procoracoid

Lumbars

Sacrals

Caudals

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8
Q

What are the functions of the ribs and sternum?

A

(Amniotes)
Breathing

Sites for muscle attachment

Shapes and strengthens body wall

Protect organs

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9
Q

What are the components of a general vertebral form?

A

Notochord

Centrum

Only in tail:
- Hemal arch
- Hemal canal
- Hemal Spine

Neural spine

Neural arch

Neural Canal

Spinal cord

Pleurocentrum
- Forms vertebral body in amniotes

Absent in mammals:
- Intercentrum

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10
Q
A
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11
Q

What does apophyses mean?

A

Apo = away
Physis = growth

= Offshoot

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12
Q

What are apophyses?

A

Projections from the vertebrae

e.g.

Zygapophyses
(articular processes)

Diapophysis
(transverse process)

Parapophysis

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13
Q

What do the ribs connect to?

A

The diapophysis and the parapophysis

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14
Q

What is the notochord?

A

The nerve cord/spinal cord that goes through the vertebrae

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15
Q

How do the vertebrae develop?

A

After gastrulation (formation of gut)

NEURULATION (formation of neural tube)

Simultaneously:
- Notochord forms
- Somite form
–> Dermatome (dermis)
–> Myotome (muscles)
–> Sclerotome (vertebrae and ribs)

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16
Q

What do the vertebrae and ribs develop from?

A

Somites which develop into
Sclerotome!!

Sclerotome develops into vertebrae and ribs!!

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17
Q

What are the stages of vertebrae development?

A
  1. Somite formation, split into dermatome, myotome and sclerotomes
  2. Split into primary sclerotome and secondary sclerotome
  3. Both primary and secondary sclerotome wrap around notochord and form the vertebra
  4. Parichordal ring wraps round the notochord and then protrusions form the other parts of the vertebra either side
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18
Q

What are vertebrae and ribs derived from?

A

Sclerotome

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19
Q

What do we know about vertebra in water vs land animals?

A

Water - pressure all around
Land - pressure only down

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20
Q

What must the vertebrae do?

A

Resist axial compression
Some stiffness in lateral bending
But maintain flexibility

+ Resist bending loads
Maintian rigidity between supports

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21
Q

What do we know about land animals and their vertebrae, regarding the dorso-ventral flexion?

A

Must resist dorso-ventral flexion

Large neural spines provide stiffness

Attachment for ligaments

Most prominent when resisting

Large bending torque

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22
Q

What do the zygapophyses do in land animals?

A

Resist bending and torsion

(resist lateral torsion)

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23
Q

Are zygapophyses in acquatic taxa?

A

No, they are usually absent

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24
Q

What do we know about regional specialisation in fish?

A

Two regions

Trunk and caudal

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25
What do we know about regional specialisation in early tetrapods?
Four regions - Cervical - Trunk - Sacral - Caudal Hindlimbs attach to Sacral region Cervical Maintain aquatic adaptations e.g. broad tail
26
Why do early tetrapods have a cervical region?
Planted legs limit head movement due to spinal flexion
27
What is the regional specialisation of primitive amniotes?
4 regions: - Cervical - Thoracolumbar - Sacral - Caudal Ribs shorten towards hindlimbs. Improves hindlimb range of motion Sacral region more robust
28
What is the regional specialisation of early mammals?
5 regions: - Cervical - Thorax - Lumbar - Sacral - Caudal Throacolumbar region further divided into: - Thorax (ribs) - Lumbar (no ribs) --> Promotes rapid locomotion --> Reflects active lifestyle
29
What is the thoracolumbar region further divided into in Early Mammals?
Throacolumbar region further divided into: - Thorax (ribs) - Lumbar (no ribs) --> Promotes rapid locomotion --> Reflects active lifestyle
30
In amniotes, what does the head rotate on?
Two specialised cervical vertebrae Axis Atlas
31
Which, the axis or atlas, is responsible for nodding?
Atlas
32
Which, the atlas or axis, is important for twisting?
Atlas twists on axis
33
What is the avian specialisation of cervical vertebrae?
Birds often have many cervical vertebrae Allows for a greater range of motion and specialisation
34
What are sauropsids and their cervical vertebrae?
Birds, reptiles, and their ancestors Representatives with many cervical vertebrae
35
What are the cervical vertebrae limits in mammals?
Mammals are very limited; always around 7 Adding cervical vertebrae associated with cancer!!
36
Describe the thoracic: ribs:
Usually articulate with vertebrae Absent in tail
37
What do we know about thoracic ribs in fish?
IF PRESENT (not always) Dorsal and/or ventral set Site for muscle attachment Stiffen body wall - Protect viscera - Shape body
38
What do we know about thoracic ribs in amphibians?
Relatively short
39
What do we know about thoracic ribs in amniotes?
Also used in breathing
40
What are the three types of ribs?
True ribs False ribs Floating ribs
41
What are true ribs?
Ribs that attach directly to the sternum
42
What are false ribs?
Attach to the 7th costal cartilage
43
What are floating ribs?
Ribs with no anterior attachment
44
What do we know about the sternum?
Tetrapod feature (not fish) Associated with pectoral girdle
45
What is the sternum like in amphibians?
Simple, not attached to ribs
46
What is the sternum like in amniotes?
Attached to ribs
47
What is the sternum secondarily lost in?
Turtles Snakes Most limbless lizards Caecilians (Snakes, most limbless lizards and caecilians are all limbless)
48
What are the features of the salamander sternum (amphibian)?
Sternal cartilage Scapula Suprascapular cartilage
49
What are the features of the frog sternum (amphibian)?
Episternal cartilage Omosternum Xiphisternum Xiphoid cartilage Procoracoid Clavicle Suprascapular cartilage Cleithrum Scapula
50
What are the features of a lizard (amniote) sternum?
Interclavicle Procoracoid Fenestrae Scapula Glenoid fossa Sternal cartilage Ribs
51
What are the features of a human sternum?
Manubrium Body Sternebrae Xiphoid process Xiphisternum Xiphoid cartilage Clavicle Scapula
52
What do we know about the shape of the bird sternum?
Has large carina ("Keel") for flight muscle attachment
53
What do we know about the shape of the bat sternum?
Bats have a slight keel on sternum Scapula is more well-developed
54
Do birds and bats have the same flight style?
NO Different muscle recruitment Pectoralis not as powerful in bats, but longer stroke
55
What are the features of bird sternums?
Carina Sternum Xiphisternal process Procoracoid Furcula (wishbone) Humerus Scapula Uncinate process Caudal vertebrae Pygostyle
56
What are the features of bat sternums?
Sternebrae Manubrium Clavicle Coracoid process Acromion Rib Lumbar region
57
What do we know about the thorax of turtles, their ribs and vertebrae?
Turtles have a carapace - Expanded ribs - Fused vertebrae - Dermal bones No sternum Appendicular skeleton within the rib cage (only in turtles)
58
What is a Carapace?
In turtles Expanded ribs Fused vertebrae Dermal bones
59
What do we know about Draco and the thorax?
Has evolved multiple times Ribs can expand outwards to "puff out" their chests and retract inwards to be skinny
60
What are the structures to the side of the vertebrae in fish?
Diapophyses
61
What is in the lumbar region of the vertebrae?
No ribs Transverse processes: site of ligament attachment Thought to be indicative of locomotor mode
62
How does the lumbar region affect speed (FAST)?
Cheetah gallop - collected fore-hind contacts --> MORE SPINE FLEXION Increases stride length Recruits axial musculature / ligaments
63
What does increased spinal flexion of the lumbar region do?
Increases stride length Recruites axial musculature/ligaments Faster!
64
How does the lumbar region affect speed (SLOW)?
Elephant amble: More distributed foot contacts --> Little spinal flexion
65
What does limited spinal flexion of the lumbar region do?
More distributed foot contacts SLOWER
66
What is the mammal sacrum?
Fused vertebrae Transmit force from hindlimbs to body via axial skeleton
67
What is the role of the mammal sacrum?
To transmit force from the hindlimbs to the body via the axial skeleton
68
What are the features of the mammal sacrum?
Wings of sacrum Auricular surface (articulates with the ilium) Sacral foramen Spinous processes
69
How many sacral foramen are fused in horses?
5
70
How many sacral foramen are fused in dogs?
3
71
How many sacral foramen are fused in humans?
Women: 5 Men: 5
72
What does the cervical region specialisation in avians do?
Allows their neck and beak to function like an arm
73
What happens to somites during vertebrae development?
Somites split apart and then rejoin with another somite to form the secondary sclerotome Secondary somites start to migrate back up to form the neural tube
74
What do we know about the sacrum of birds?
Portions of thoracic, lumbar and sacral region fused to form the Synsacrum Reduce musculature for stabilisation - less weight Also houses the lumbosacral organ.
75
What is the Synsacrum?
Portions of thoracic, lumbar and sacral region fused together
76
What is the role of the lumbosacral organ?
Fluid filled region Helps with balance, like the inner ear
77
What is the caudal region?
One of two main regions in fish - So VERY important Preserved in many reptiles Tails reduced in birds, terrestrial mammals - Other hip extensors - Reduced or absent chevrons
78
What is the main feature of the caudal region (think chevron)?
Hemal Arch - Chevron bones For muscle attachment
79
What is the primary hip extensor in the caudal region of reptiles?
Caudofemoralis longus
80
What do we know about the caudal region in Whales?
Whales re-evolved the chevron for muscle attachment No cordofemoralis longus = No femur!!!
81
What do we know about the frog skeleton?
SUPER WEIRD No more than 9 pre-sacral vertebrae Single scaral vertebra Post-sacrally, the urostyle - Fusion of post-sacral vertebrae Part of a large suite of adaptations for SALTATION (hopping)
82
What do we know about the snake skeleton?
Majority of vertebrae are thoracic and caudal No sternum
83
What do we know about snake locomotion?
All locomotion derived from axial musculature via axial skeleton Extremely versatile "Sidewinding" "Swimming" "Gliding" "'Lasso' climbing"
84
Describe snakes vs limbless lizards:
Snakes are mostly thoracic vertebrae and some lumbar and caudal Limbless lizards have a much longer tail
85
How can you tell where the non-thoracic vertebrae start?
Lack of ribs
86
What do we know about legless lizards and sternum?
They sometimes retain a sternum (and oftern vestigial legs)
87
What are the horizontal projections on the caudal vertebrae?
Transverse processes

Comparative Anatomy (10 decks)

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