Locomotor - comparative locomotion Flashcards
Why does locomotion exist?
To move limbs and the centre of mass on different terrains in different directions
To resist ground force reaction
-this increases with speed, incline and lameness
-30% higher on firelimb than hind
What types of environment are there?
Terrestrial - walking, runing, sliding, underground (fossorial) and arboreal (living in trees)
Aerial - flying and soaring
Aquatic - swimming and benthic (walking in water)
What is the significance of leg design?
Length of segments can vary
Postures
Size and location of bony processes and muscle attachments
What are examples of the differences of the length of segments?
Examples
Kangaroos have large strong hindlimbs for hopping and small forearms as they don’t use them as much
Gibbons/primates have brachiation for swinging through trees.
What are examples of posture differences?
Cheetahs have flexible spines to recycle energy and enhance locomotion.
When greyhounds run in a circle, they have their body at an angle for better speed.
What is the significance of where the muscles attach?
Work = force x distance
Torque (rotational force) = muscle force x movement arm
So large arms make it possible to move large loads with smaller forces
Large movement arms mean less absolute movement for given force applied.
Proximal insertion for speed, distal insertion for strength
What is the significance of body size?
Area increases at slower rate than volume so muscle force stays small.
Large animals
-Need large straight limbs with upright posture so force right up the less
-Restricted to slower movements
Small animals
-less energy efficient as need to take more steps
What is plantigrade?
Walks with feet planted flat on the ground e.g. badgers and bears
What is digtigrade?
Walks on toes e.g. cheetahs and dogs
What is unguligrade?
Walks on hooves e.g. horses and ruminants
What are the definitions of bipedals?
Walks on two legs
Less stable support as centre of mass is directly above the support base
This frees forelimbs for other functions e.g. arms/wings
What are the features of quadrupeds?
4 limbs to move across a variety of terrains and provides a big base of support.
Limbs can be adapted for function but primary hindlimbs provide all the power and forlimbs steer.
What are cursorial animals?
Animals that travel longer distances
What are features of cursorial animals?
Distal limbs are lighter, with most of mass proximal. Even lost digits and made of mostly tendons.
Tendons in distal limbs are well adapted for rapid leg protraction
Adapted for long standing
How do the tendons act as power amplifiers?
Biceps brachii stretch when carpus is locked in extension
Lacertus fibrosus/bicep tendon and internal tendons/digital flexors store elastic energy
When the carpal buckles the energy is released as the tendon is rapidly shortened.
System crucial to move the mass
