Brent Cornell

    
Muscles connect to bones (via tendons) and contract to provide the force required to produce movement

• The muscle connects a static bone (point of origin) to a moving bone (point of insertion)

Skeletal muscles exist in antagonistic pairs (when one contracts, the other relaxes) to enable opposing movements 

• Opposing movements may include: flexion vs extension, abduction vs adduction, protraction vs retraction, etc.

    
Many types of insects (including grasshoppers and praying mantises) have hind legs that are specialised for jumping

• The jointed exoskeleton of the hind leg is divided into three parts: femur (upper leg), tibia (middle leg) and tarsus (lower leg)
• The femur and tibia are connected by two antagonistic muscles: flexor tibiae muscle and extensor tibiae muscle

When the flexor muscle contracts, the extensor muscle relaxes and the tibia and femur are brought closer together

• This retracts the hind quarters in preparation for pushing off the ground

When the extensor muscle contracts, the flexor muscle relaxes and the tibia is pushed away from the femur

• This extends the hind quarters and causes the insect to jump

Antagonistic Muscle Pairs in an Insect Leg

Jumping Motion of a Praying Mantis