Final answer:
The joint movement being performed when standing on the tips of the toes to reach something high is plantar flexion, which lifts the heel by pointing the toes downward.
Step-by-step explanation:
When you stand on the tips of your toes to reach the top shelf, you are performing plantar flexion. This movement involves bending at the ankle to lift the heel off the ground and point the toes downward. It is distinct from dorsiflexion, which moves the top of the foot toward the anterior leg; inversion, where the bottom of the foot angles toward the midline; and eversion, which turns the bottom of the foot away from the midline. In this scenario, plantar flexion is the action that allows you to raise your body higher.