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Clinical exam · Nervous system

Babinski sign !

  • Sign

When the sole is stroked, the big toe goes up instead of down; in adults it means damage to the brain or spinal cord motor pathway.

Updated 2026-11-01

See it in 3D: Spinal cord · Motor cortex

What it is

The normal adult plantar response is flexion of the toes when the outer edge of the sole is stimulated. The Babinski sign is the extensor response: the big toe extends slowly and the other toes may fan out. It is the classic sign of a corticospinal tract (upper motor neuron) lesion and is normal only in infants.

The anatomy it tests

  • Tests the corticospinal tract from the precentral gyrus to the lumbosacral cord.
  • The plantar reflex arc uses the L5–S1 roots and the tibial nerve.
  • A normal corticospinal tract turns the primitive extensor response into a flexor one; when it is damaged, the primitive response returns.

How to elicit it

  1. Patient lying down with the leg straight and relaxed; warn the patient they will feel a firm stroke.
  2. The examiner steadies the ankle with one hand.
  3. With a blunt object (the hammer handle or a key), stroke the lateral edge of the sole from the heel forward.
  4. On reaching the base of the toes, curve the stroke towards the base of the big toe.
  5. Watch the first movement of the big toe: flexion (normal) or slow extension (Babinski).
  6. Repeat on the other foot and compare.

What a positive result means

  • Positive (big-toe extension, with or without fanning of the others): an upper motor neuron lesion anywhere from the cortex to the spinal cord.
  • Classic causes: stroke, multiple sclerosis, brain tumour or trauma, cervical myelopathy, spinal cord injury, meningitis or encephalitis, amyotrophic lateral sclerosis.
  • Bilateral in metabolic coma or after a seizure.
  • A flexor plantar response does not rule out an upper motor neuron lesion, especially in the acute phase.

Usefulness and limits

  • Fairly specific for an upper motor neuron lesion but only moderately sensitive.
  • Voluntary withdrawal from tickling is mistaken for a Babinski: withdrawal is fast and moves the whole leg.
  • Stimulating the middle of the sole can trigger a toe grasp reflex.

Test yourself

Think of the answer, then tap the question to see it.

Which pathway does the Babinski sign test?

The corticospinal tract (upper motor neuron); damage to it brings back the primitive extensor response.

At what age is an extensor plantar response normal?

In infants, up to about 1 to 2 years of age.

How is a Babinski sign told apart from withdrawal due to tickling?

The Babinski is a slow extension of the big toe; withdrawal is quick, voluntary or ticklish, and moves the whole foot and leg.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

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Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: How To Assess Reflexes (MSD Manual Professional Edition, 2024); Babinski reflex (MedlinePlus, U.S. National Library of Medicine, 2024); 16.4 The Sensory and Motor Exams (OpenStax, Anatomy and Physiology 2e, 2022).

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