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Topic 11: Support & Locomotion on Land

� What forces is the body subjected to on land?

� How do vertebrates move?

� Balance

� Posture

� Gait

� How is the vertebral column involved in

locomotion?

� Support

� Movement

� How are the limbs involved in locomotion?

Musculoskeletal Integration

Muscles act on the skeleton to

exert forces on the environment

www.merckmanuals.com, Body Worlds

What forces is a body subjected to on land?

� When moving

� ________ – impact from pushing off the ground

� ___________ component

� F = ma = mg = 9.81 x m

� ___________ component

� Landing

� What are some adaptations

for resisting forces an animal is subjected to on

land?

Photo PJB

� What are some adaptations

for resisting these forces?

Liem et al. Fig. 11-11

What forces is a body subjected to on land?

� What are some adaptations

for resisting these forces?

© www.breg.com, www.medicalook.com

What forces is a body subjected to on land?

� GRF at impact is

influenced by:

� ______________

� Footwear

Lieberman et al. 2010

What forces is a body subjected to on land?

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� GRF at impact is

influenced by:

� Running technique

� Footwear

� Shoes

� Decrease ____________

� Not impact force

� Fore-Foot Strike decreases

� _____________

� _____________

Lieberman et al. 2010

What forces is a body

subjected to on land? How do vertebrates move?

� _______________

� In balance – COM within triangle of stability

� Out of balance – COM falls outside of triangles

� Stability is proportional to width of triangles

� Who is more stable? Sprawling or erect posture?

Liem et al. Fig. 11-19

� _____________� Sprawling

� Erect (can be bipedal)

� Differ in orientation of limbs relative to body

� Vertebral function also differs

Photos © PJB, S Yamamoto

How do vertebrates

move?

� What posture does the chameleon have?

Photos © KP Bergmann

How do vertebrates move?

� ____________

� Components

� ____________

� ________________

� ____________

� Symmetrical gaits� Left & Right limbs are

~50% out of phase

� Asymetrical gaits� Left & Right limbs

become in phase

Liem et al. Fig. 11-19

How do vertebrates move?

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Gait

What do you notice happens as velocity increases?

Liem et al. Fig. 11-20

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Gaits

� Gaits are often poorly defined in sprawling vertebrates

� Crocodylus johnstoni

� Can gallop

� More upright posture

� Often only two feet on the ground

© A Britton

What is the role of the vertebral column?

Kardong Fig 8-30; Liem et al. Fig. 11-9, 11-8

� ____________________� Suspension of viscera

� Connecting front & hind limbs

� Restriction of ___________ _____________

� Zygapophyses and torsion

� Centra and bending

� Neural spines with ligaments and bending

Pough et al. 2004, Fig. 10-2; PJB

� Movement

� ___________ displacement

� Spralwers

� Enhanced stride length

What is the role of the

vertebral column?

Vertebrate Life Fig 24-2; Liem et al. Fig. 11-26

� Movement

� ___________ displacement

� Erect posture

� Also enhances stride length

� Fast locomotion

� Gallop

� Bounding

What is the role of the vertebral column?

Pough et al. Fig. 10-11; PJB

� Extreme lateral movement

What is the role of the vertebral column?

Liem et al. Fig. 11-27

� ______________ of movement

� Frogs

� Evolution of urostyle

� Reduction in vertebral number

� Bending only at sacroiliac joint

What is the role of the vertebral column?

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What is the role

of the limbs?

� Interface with substrate

� Minimize contact with

substrate� Decreased friction with body

� How do the roles of the front

& hind limbs compare?

� Terrestrial

� Arboreal

� Jumping

Photos © KP Bergmann, National Geographic

� Adaptations for speed

� Lengthening of distal

elements

� Increase ________

� Increase ________ _________

Liem et al. Fig. 11-22

�Arc length is the same

- Distance travelled is

proportional to limb length

What is the role of the limbs?

� The further distally you go:

� The longer the distance moved

� The greater the velocity

Liem et al. Fig. 11-24

What is the role of the limbs?

� Trade-off between speed and power

� What class of lever is this?

� How do the limbs differ in

in-lever and out-lever?

Liem et al. Fig. 11-21

What is the role of the limbs?

� Consider the following:

� Fi x Li = Fo x Lo

� Fo = (Fi x Li) / Lo

� How do you increase force morphologically?

� Vo x Li = Vi x Lo

� Vo = (Vi x Lo) / Li

� Ho do you increase velocity morphologically?

� Gear Ratio = Lo / Li

� What does a low Lo / Li mean?

� What does a high Lo / Li mean?

Liem et al. Fig. 11-21

What is the role of

the limbs?