Symmetrical Tonic Neck Reflex (STNR)

The symmetrical tonic neck reflex (STNR), or crawling reflex, is an infant reflex that shows up between 6 and 9 months of age. It supports a baby’s movement from lying down to getting onto their hands and knees. It helps them learn how to crawl by coordinating their upper and lower body.

When they look up, their arms straighten, and their legs bend. When they look down, their arms bend and their legs straighten.

As crawling develops, the STNR gradually fades before your baby’s first year. Their brain gets better at controlling this movement on its own.

What is the purpose of the STNR?

This reflex helps your baby learn how to control their body as they grow. It supports the following during movement:

• Coordination
• Focus
• Posture

It helps babies move between their upper and lower bodies. It’s also part of activities like sitting upright, crawling and playing with toys or a ball.

What triggers the STNR?

There isn’t a formal test for this reflex. It shows up naturally when it’s active. You or your child’s provider can watch for it this way:

• When your baby is on their hands and knees and tucks their chin down, their arms may bend and their legs may straighten.
• When your baby lifts their head to look up, their arms may straighten and their legs may bend.

It’s easiest to notice this during tummy time or when your baby tries to push up from the floor. You’re only watching natural movement. You shouldn’t pull, push or force your baby’s head or body.

At what age does the STNR disappear?

The STNR usually fades between 9 and 11 months of age. During this time, your child gains better control over their body and starts making more intentional movements.

Don’t panic if your baby’s reflex isn’t going away exactly on schedule. Some kids develop sooner or later than others. Talk to their provider if you have any concerns.

What is a retained STNR?

A retained STNR means the reflex doesn’t fade when it’s supposed to. This reflex usually turns off before your child’s first year, as their brain matures. When it stays active, bending or lifting their head can still cause automatic movements in their arms and legs.

STNR is a primitive reflex. This means it’s an automatic movement babies have. If it stays active past early development, it may interfere with how they move and function when they grow. This might affect skills that need good posture, coordination and body control.

What conditions are the STNR associated with?

If this reflex stays active past infancy, it may offer information to providers about how your child’s nervous system is developing. Studies suggest this pattern is seen more often in some children who also have common neurodevelopmental conditions like:

• ADHD
• Autism
• Cerebral palsy

This doesn’t mean STNR causes these conditions. Providers look at it as one piece of information, along with many others, when understanding a child’s development. This isn’t used to make a diagnosis on its own.

If you notice that your child isn’t crawling, getting onto their hands or knees or meeting other developmental milestones for their age, reach out to their pediatrician.

What are STNR exercises?

A physical therapist or occupational therapist may help with retention. They’ll create a plan based on your child’s needs. This varies from person to person.

Here are some examples of activities a therapist may use to help your child meet their goals:

• Lizard walk: Your child starts on their stomach or in a very low crawl position with their belly close to the floor. They use their arms to pull forward while keeping their body low. One arm moves forward with the opposite leg. They keep alternating sides in a slow, steady way.
• Starfish jumps: Your child stands with their feet together and arms at their sides. They jump and spread their arms and legs wide like a starfish. They land with control and repeat the movement in a steady rhythm.
• Single-leg hopping: Your child stands on one foot and lifts the other foot off the floor. After holding balance for a moment, they hop forward using small hops. Then, they switch feet and repeat.

Your child’s provider may recommend practicing exercises in their office and at home with supervision. They’ll show you how to do each activity safely to prevent injury.