From Head to Toe: How the Symmetric Tonic Neck Reflex Brings Upper & Lower Body Together

The Symmetric Tonic Neck Reflex helps babies connect the movements of their upper and lower body.

STNR Explained: From Head to Toe (Audio Blog)

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What are primitive reflexes?

A reflex is the body’s automatic way of responding to our environment, like blinking when something comes too close to your eyes. Babies are born with a special set of these responses, called primitive reflexes, that begin developing before they're born. These reflexes act as the body’s early stepping stones that help babies survive and slowly build the strength for movement and coordination.

Primitive reflexes each influence different parts of the body and serve unique purposes. For example, the Asymmetric Tonic Neck Reflex (ATNR) helps babies coordinate the right and left sides of their body, a skill needed later for activities like walking, riding a bike, or even opening a jar. The Symmetric Tonic Neck Reflex (STNR) teaches babies to separate upper and lower body movements and is the topic we will be exploring. As Healthline explains, “the STNR helps your baby get onto their hands and knees, so it’s sometimes referred to as the crawling reflex” [4]. The Spinal Galant Reflex supports crawling motions while the Tonic Labyrinthine Reflex (TLR) links head position to posture and balance. Working together, these reflexes create the foundation for smooth movement and more advanced motor skills as your baby grows.

What is the Symmetric Tonic Neck Reflex?

The Symmetric Tonic Neck Reflex usually appears between 6–9 months of age and plays a very big role in preparing your baby for crawling. When your baby looks down, their arms bend and legs straighten; when they look up, their arms straighten and legs bend. This alternating pattern teaches babies to coordinate the top and bottom halves of their body separately which is such an important step for crawling on all fours, sitting upright, and eventually walking.

By giving babies practice shifting between these positions, the STNR also strengthens their core muscles and helps them learn how to balance their body against gravity, which is necessary when learning to stand. It’s an important transitional reflex that helps bridge the gap from lying on the floor to moving independently all over your home.

What are issues associated with a retained Symmetric Tonic Neck Reflex?

The STNR normally fades by around 11 months, once your baby has mastered sitting and crawling. If it stays active for longer than this, it may create challenges with learning and balance. Children with a retained STNR might slump at a desk, have trouble copying from the board in school, and struggle with tasks that require coordinated eye movements, like reading and writing.

Retention can also show up in physical activities. Kids may find it difficult to swim or play sports because the reflex continues to interfere with how the upper and lower body coordinate. Because posture and visual tracking are closely tied to learning, lingering STNR is also linked to restlessness and poor handwriting.

How to test for a retained Symmetric Tonic Neck Reflex

You can test the STNR by placing your child on their hands and knees. Gently guide their head up and down. If their arms and legs automatically move into the reflex pattern which shows as the arms straightening with the head up and bending with the head down, beyond the typical age, it may suggest that the reflex has not fully integrated.

What can you do about a retained Symmetric Tonic Neck Reflex?

The first step in addressing a lingering STNR is checking it in infancy. By following the steps above, you can see whether your baby's arms and legs follow the reflex pattern. If the reflex doesn’t fade on schedule, you may notice issues as your child grows. This might include trouble focusing in school. Bringing these concerns to a pediatrician is important. Occupational or physical therapists can assess the reflex more closely and recommend activities that help integrate it. Often disguised as playful movements, these exercises work to strengthen the core and improve coordination between the upper and lower body. Early support can help to make these challenges easier to deal with and even heighten the possibility to overcome them, which gives your child so much more confidence.

Sources:

1. Arcilla, C. K., & Vilella, R. C. (2023, May 1). Tonic Neck Reflex. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559210/

2. "Retained Primitive Reflexes as a Sign of Brain Imbalance", Brain Balance Centers, https://www.brainbalancecenters.com/blog/retained-primitive-reflexes-sign-brain-imbalance

3. Understanding Primitive Reflexes: A Dynamic perspective on Sensory Motor Development. (n.d.). https://sensoryhealth.org/node/2060

4. Frothingham, Scott. “All About the Symmetric Tonic Neck Reflex.” Healthline, 30 Sept. 2020, www.healthline.com/health/baby/symmetric-tonic-neck-reflex?utm

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