1.14 Comparative locomotion Flashcards
Describe the relationship between mass of animal and energy needed to move the animal
20x more energy needed to move a horse than a mouse
- so the higher the mass of the animal the more energy required to move them
Describe the relationship between speed and limb force/bone strain
Both increase with speed
How does the distal limb act?
Linear elastic spring
- length change is due to linked extension of the MCP and DIP joints
Are there advantages to having a highly/passive elastic limb?
- adjustment for different gaits/speeds
- slowing down/absorbing energy
- compensation for injury/pain
- adaptation to different ground surfaces
- leg is susceptible to vibration
Describe the fibre length of the lateral and medial heads of the biceps?
Medial = longer fibres Lateral = extremely short fibres, significant passive properties
What limits acceleration?
- Lower speed = geometry limited
- Higher speed = power limited
What limits deceleration?
Geometry limited
How is a moment created at a joint?
As the force vector is a distance away from the DIP joint the GRF creates a moment at the joint
How is a moment arm created at a joint?
Distance between the PZM and the centre of rotation of the DIP joint is termed the moment arm
What is navicular disease?
Inflammation or degeneration of the navicular bone and the surrounding tissues, usually forelimb
What is a potential hypothesis for navicular disease?
Compressive stress on navicular bone is greater in horses with navicular disease than in normal horses
- due to contraction of DDF muscle to avoid concussion of painful heel region
Why does an increase in DDFT force due to toe landing first occur?
Normal force pattern is due to passive loading via the accessory ligament
- difference in DDFT force between normal and navicular horses = 3kN
- contraction of the deep digital flexor muscle can account for this difference
