Understanding the Asymmetrical Tonic Neck Reflex (ATNR)
The human body goes through various developmental stages, particularly during infancy, where primitive reflexes play a crucial role in early movement and neurological development. One such reflex is the Asymmetrical Tonic Neck Reflex (ATNR), an essential component in the early stages of motor development. While it is a normal and expected reflex in newborns, its persistence beyond infancy can lead to developmental challenges.
What is ATNR?
The Asymmetrical Tonic Neck Reflex (ATNR) is a primitive reflex that emerges in utero and is typically present at birth. It is characterized by an automatic movement pattern where passively turning a baby’s head to one side causes the arm and leg on that side to extend while the opposite limbs flex. This reflex is sometimes referred to as the “fencing reflex”because it resembles a fencer’s stance. 
What is the purpose of ATNR?
ATNR serves several critical functions in early development:
– Assists in Birth Process: Helps the baby navigate through the birth canal during delivery.
– Facilitates Hand-Eye Coordination: Encourages visual tracking by linking head movements with arm extension.
– Aids in Early Motor Development: Lays the groundwork for rolling, reaching, finding mid-line, developing dominance and perceptual development
When Should ATNR Integrate?
ATNR is typically active from birth to about 4–6 months of age. As the central nervous system matures, this reflex should gradually integrate between the 6-7th month of age into the whole motor system, allowing for more voluntary and refined motor movements.
What Happens if ATNR Persists?
If ATNR is not properly integrated and remains active beyond six-seven months, it may interfere with development.
Persistent ATNR can contribute to:
– Delayed Motor Development: Difficulty with crawling (cross lateral movements), throwing and catching
– Poor Handwriting and Fine Motor Skills: Struggles with holding a pencil, cutting, or using utensils. Difficulty crossing the midline
– Coordination Issues: Difficulty in bilateral coordination (using both hands together effectively).
– Reading and Learning Challenges: Trouble with left-to-right tracking, affecting reading fluency.
– Attention and focus: Problems maintaining attention, focus, and memory
How to integrate the ATNR
For children (or even adults) with retained ATNR, specific exercises and therapies can help integrate the reflex. These may include:
– Cross-Lateral Movements: Activities like crawling, cross-body marches, climbing walls or bilateral coordination games.
– Neuromodulation Therapy: Guided exercises focusing on reflex integration, active and/or passive
– : Working with therapists to develop motor skills and coordination.
Conclusion
ATNR is a vital reflex for neuromotor development, but if it persists beyond the typical age range, it can create challenges in movement, coordination, and learning. Recognizing and addressing retained ATNR through targeted exercises and therapy can help individuals overcome these difficulties and support their overall development. If you suspect a retained ATNR in your child, consulting a healthcare professional or therapist with specialist training can provide guidance and intervention strategies.
Understanding reflex integration is key to fostering smoother motor development and learning pathways, setting the foundation for a child’s future growth and success.
Lara Cawthra BSc. MChiro. MCSc (Paeds.) FRCC (Paeds.)
Chiropractor and MNRI Core Specialist
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