Definition
Stroking the lateral part of the sole of the foot with a fairly sharp object produces plantar flexion of the big toe; often there is also flexion and adduction of the other toes. This normal response is termed the flexor plantar reflex.
In some patients, stroking the sole produces extension (dorsiflexion) of the big toe, often with extension and abduction ("fanning") of the other toes. This abnormal response is termed the extensor plantar reflex, or Babinski reflex.