The plantar reflex is a reflex elicited when the sole of the foot is stimulated with a blunt instrument, and this procedure tests the integrity of the corticospinal tracts [1]. In infants, stimulation of the lateral plantar surface normally elicits plantar flexion of the toes, known as the flexion withdrawal response [2]. As the corticospinal tracts mature, this is replaced by the normal adult plantar reflex where the great toe dorsiflexes downward when the lateral sole is stimulated [1][3].

An upward moving great toe following plantar stimulation is called the Babinski sign, indicating corticospinal tract disease [1][4]. This extensor response is due to contraction of the extensor hallucis longus, best elicited by slow stroking the lateral sole with a pointed reflex hammer [5][6]. The Babinski reflex implies upper motor neuron damage and can even produce crossed dorsiflexion of the opposite great toe in severe bilateral corticospinal disease [4]. It was first described by Babinski in 1896 as an abnormal reflex in adults that persists from the normal infantile pattern [3].