Reflex: Babinski Sign
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Babinski sign
- Great toe extends. Other toes fan out.
Anatomy
- Demonstrates a lesion of the corticospinal tract above L1.
- The reflex, itself, extends from S1 to L1.
Detailed Description
- The very first sign of abnormality is slight contraction of the tensor fascia lata (muscle of the thigh) as the outside of the foot is stroked.
- The little toe abducts rather than adducting and flexing. As the stimulus progresses further up the foot, the great toe extends at the metatarsophalangeal joint in association with extension of the interphalangeal joints.
- The other toes abduct, fan and dorsiflex.
Interpretation
- The reflex is usually slow and unfolds in the manner described but may be jerky and repetitive.
- If the entire foot extends this may be voluntary.
- If only the great toe extends with abduction of the little toe, this is more reliable for a true Babinski sign.
- Frequently, the toe will be extended prior to the reflex being attempted in severe spastic states.
Adapted from: Robert J. Schwartzman, MD Neurologic Examination (2006) Massachusetts, USA: Blackwell Publishing. Permission from Dr. Schwartzman for adaptation of this image.