Which sign is indicated by the fanning out of the toes after an infant's foot is stroked?

• A. Sucking reflex
• B. Rooting reflex
• C. Babinski reflex
• D. Plantar grasp

Answer: (C)

A positive Babinski sign reflects how the corticospinal tract interacts with the spinal reflexes. When the sole is stroked, the normal adult response is plantar flexion of the toes. The Babinski pattern—dorsiflexion of the big toe with fanning of the other toes—happens because the corticospinal system hasn’t fully matureited in infants, so this upward toe motion is the typical response in early life.

In infants, this fanning is normal because the corticospinal tract is still developing. As the nervous system matures, the response shifts to the adult pattern of toe curling downward with plantar flexion. If a Babinski sign appears in older children or adults, it suggests an upper motor neuron or pyramidal tract problem.

Other reflexes listed are different responses to other stimulations: a sucking reflex is the automatic sucking movement, a rooting reflex is turning the head toward a stroked cheek, and a plantar grasp is curling the toes when the sole is stroked. The toe fanning after stroking the sole is specifically the Babinski sign.