Which reflex is elicited by stimulating the sole of the foot with a blunt instrument and is characterized by toe movement (curling in adults, fanning in babies)?

• A. Clonus
• B. CN
• C. Babinski
• D. Gait

Answer: (C)

Stroking the sole tests the plantar reflex. In a typical adult, the toes curl downward in response. The distinctive sign you look for with this stimulus is dorsiflexion of the big toe with spreading (fanning) of the other toes—this is the Babinski response. It’s normal in infants because their corticospinal tract isn’t fully myelinated yet, so toe fanning can occur without an underlying problem. In adults, seeing this toe extension with toe spreading indicates an upper motor neuron lesion affecting the corticospinal tract. The other options don’t describe the reflex pattern produced by sole stimulation, whereas Babinski is the classic signs linked to this test.