T11 Land Locomotion wrksht.ppt - Clark University
Transcript of T11 Land Locomotion wrksht.ppt - Clark University
1/10/2013
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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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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?