Sophia accidentally steps on a nail. she reflexively pulls her foot up. this movement was done without the involvement of -nerves -the brain -the spinal cord -muscles `kay

Sophia accidentally steps on a nail. She reflexively pulls her foot up. This movement was done without the involvement of the brain.

Explanation:

This reaction to pain and harmful stimuli is called the withdrawal or crossed extensor reflex. Here, the afferent nerve fibers leading away from the stimulated region of the leg, crosses to the opposite or contralateral side of the spinal cord where they synapse with interneurons. These then inhibit or excite alpha motor neurons leading to to the muscles of the opposite leg. So, the flexor muscles in the affected leg contract while its extensors relax, while the opposite occurs in the other leg.