Crossed Extension Reflex

Published July 2, 2026 Read time 1 min read Readers 1

What is the "Crossed Extension Reflex" used for?

The crossed extension reflex, also known as Philippson reflex, is present at birth and normally disappears by 1 to 2 months of age:

If it is absent at birth, the neonate may have flaccid paralysis.
Its presence beyond 2 months of age is indicative of a partial or incomplete spinal lesion or neurologic dysfunction.

The infant is placed supine with the lower limbs in midline and the hips and knees extended.
The reflex is elicited by holding one lower limb in extension at the knee and applying firm pressure by rubbing or stroking the sole.

The opposite, free hip will initially flex and abduct, then adduct and extend, as if the infant were trying to push away from the stimulus.
There may be associated fanning of the toes of the stimulated leg.
Stimulation of the sole of the foot causes flexion of the ipsilateral limb, moving it away from the stimulus, and extension of the contralateral limb, moving it toward the stimulus.
In neonates, a similar response can be elicited by applying strong pressure in the inguinal region, which causes flexion of the ipsilateral limb and extension of the contralateral hip and knee.