Final answer:
Contraction of the calf muscles, including the gastrocnemius and soleus, causes plantar flexion of the foot, lowering the sole to the ground and assisting in movements like jumping and maintaining posture.
Step-by-step explanation:
The contraction of the calf muscles, specifically the gastrocnemius and soleus muscles, causes plantar flexion of the foot.
This movement lowers the sole of the foot to the ground as when foot-tapping, jumping, or standing on one's toes.
The calf muscles attach to the heel bone via the Achilles tendon, which, when pulled, allows for this action.
A simplified lever system is involved in this process. Additionally, these muscles help maintain posture while walking and assist in the rotation of the leg at the knee and thigh.
During a withdrawal reflex, such as when stepping on a tack or sharp object, the motor neurons responsible for the contraction of the tibialis anterior muscle are activated, causing dorsiflexion of the foot, which counteracts the plantar flexion that might be in progress to avoid further injury.