What is Symmetrical Tonic Neck Reflex - STNR

 

STNR stands for Symmetrical Tonic Neck Reflex.

It is a primitive reflex seen in infants that helps prepare the body for crawling.

How STNR Works:

When the baby's head moves, the arms and legs respond in a specific way:

• Head bends forward (flexion):
  → Arms bend (flex) and legs straighten (extend)

• Head tilts back (extension):
  → Arms straighten (extend) and legs bend (flex)

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🕒 When does STNR appear and disappear?

• Emerges: Around 6 to 9 months of age

• Inhibits (disappears): By 11 to 12 months

This timing helps the baby transition from lying to crawling.

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🚩 If STNR persists beyond 12 months:

It may indicate neurological immaturity and can affect:

• Crawling

• Sitting posture

• Hand-eye coordination

• Classroom skills like copying or writing