Final answer:
When a ballerina raises onto her toes, she performs plantar flexion. Lowering back to flat feet involves dorsiflexion. These are the primary movements at the ankle joint.
Step-by-step explanation:
When a ballerina raises up onto her toes, the joint movement at the ankle is called plantar flexion. This movement involves lifting the heel of the foot from the ground or pointing the toes downward, which is essential for a ballerina to achieve the tip-toe position. Conversely, as the ballerina lowers back down to the flat of her feet, the joint movement at the ankle is known as dorsiflexion, which occurs when the top of the foot moves toward the anterior leg, allowing the ballerina to gracefully return to a flat-footed stance.