Asymmetrical Tonic Neck Reflex (ATNR): The Primitive Spiral of Reach and Recoil

Asymmetrical Tonic Neck Reflex (ATNR): The Primitive Spiral of Reach and Recoil

The Asymmetrical Tonic Neck Reflex (ATNR) emerges around 18 weeks gestation and should be fully integrated by 6 months of age. Often called the “fencer’s pose,” ATNR is activated when the infant’s head turns to one side. The result is a distinct asymmetrical pattern: the limbs on the face side extend, while the limbs on the skull side flex. This creates a rotational spiral across the body, preparing for visual–motor mapping, crossing midline, and later voluntary reach.

ATNR links early eye–hand coordination, visual tracking, and spatial mapping. It is vestibular- and proprioceptive-driven, building on the labyrinthine tone shifts of TLR. It allows the infant to begin differentiating left from right, self from other, and prepares the spine for complex contralateral movement.

Adults with an unintegrated ATNR may experience difficulties with activities that involve crossing the midline, such as reading, writing, or certain sports, as the reflex may cause involuntary movements or disruptions in coordination. Anecdotally, for me, this deeply affects emotional states while driving, where turning the head to check blind spots inadvertently cause one arm to extend and the other to flex.  To my vestibular system at that moment it feels like I am driving off a cliff.  Yes, this engenders road rage. 

Additionally, the persistent influence of ATNR can contribute to postural issues, difficulties with balance, and challenges in visual tracking, which may result in headaches or neck pain due to the strain placed on the body during everyday tasks.

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Neurological and Autonomic Profile

ATNR is mediated via:

• Cervical proprioceptors
• Vestibular system (CN VIII)
• Spinal interneurons spanning cervical and thoracic levels
• Motor output through reticulospinal and vestibulospinal tracts

Its role is primarily sensorimotor, not autonomic—but when retained, it causes compensatory postural bracing, leading to chronic sympathetic load. Left unintegrated, it fragments bilateral motor planning and undercuts vestibular-cortical communication.

Developmental Role and Reflex Hierarchy

ATNR builds on the flexion/extension tone patterns of TLR, adding a rotational component. It is essential for:

• Establishing hand–eye coordination
• Learning to roll and shift weight
• Building visual-perceptual reach
• Laying the foundation for cross-pattern movement

If ATNR persists past 6 months, it interferes with:

• Crawling
• Gait sequencing
• Reading and writing (visual tracking, hand dominance)
• Spatial orientation and midline control

ATNR must integrate before STNR and Landau Reflex can stabilize quadruped and upright positioning.

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Clinical Presentation of Retained ATNR

In older children or adults, retained ATNR presents as:

• Loss of balance when turning the head
• Visual tracking issues or eye fatigue
• Difficulty crossing midline (e.g., touching opposite shoulder or crossing legs)
• Neck or low back pain during rotation
• Asymmetrical gait or arm swing
• Postural twist under load (esp. in sitting, driving, cycling)

Clinically, the body often adapts with scoliosis-like spirals, core torsion, and compensatory fascial fixation through thoracic and pelvic lines.

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Somatic and Energetic Architecture

ATNR’s reflex arc travels diagonally across the body. It coils the fascial and postural system into opposing spirals, creating tension between reach and recoil.

Muscles Involved:

• Cervical rotators and flexors
• Shoulder flexors/extensors (deltoid, triceps, biceps)
• Obliques and QL
• Spinal rotators (multifidi, rotatores)
• Pelvic stabilizers and hip rotators

Cranial and Autonomic Structures:

• CN VIII (vestibular tracking)
• CN XI (head and neck tone)
• Cervical sympathetic ganglia
• Reticular formation and spinal motor tracts

Myofascial Lines:

• Large Intestine sinew channel (arm extension and neck rotation) — Superficial Back Line (SBL), Superficial Fr
• Small Intestine sinew channel (scapular retraction and cervical torsion) — Deep Front Line (DFL)
• Liver sinew channel (hip adduction on flexed side) — Spiral Line (SL)
• Gallbladder sinew channel (lateral stability of extended side) — Lateral Line (LL)
• Dai Mai (trunk rotation integration) — transverse stabilizer

Acupuncture Zones and Meridians:

• Gallbladder and Liver channels: rotation, eye tracking
• Small Intestine and Triple Burner: shoulder rotation and neck coiling
• DU20, GB20, SI13, LI15, GB31, LIV3, Taiyang

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Energetic Interpretation

ATNR reflects the body’s first polarity mapping. It is the template for differentiation, not unification. In TCM terms, ATNR mimics an unresolved Shao Yang pattern: pivoting between extremes, unable to reconcile rotation with groundedness.

In retained states, this spiral results in:

• One-sided dominance or weakness
• Visual–vestibular mismatch
• Energetic “torque” across the Dai Mai and GB channel
• Postural asymmetry mirrored in affect, behavior, or identity rigidity

Patients often present with complaints “on one side” or a “twisted core” that resists resolution despite structural work—indicating reflex-level imprinting.

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Summary Table

Feature	Asymmetrical Tonic Neck Reflex (ATNR)
Appears	~18 weeks gestation
Integrated by	5–6 months
Primary Movement	Head turn causes ipsilateral limb extension, contralateral limb flexion
Neuroanatomy	Vestibular + cervical proprioception → spinal motor output
ANS Effect	Indirect sympathetic load via postural compensation
Fascial Pattern	Spiral Line dominance; contralateral shearing
TCM Systems	Shao Yang, Gallbladder, Liver, Dai Mai
Clinical Red Flags	Loss of balance with head turn, scoliosis, midline instability, visual–postural mismatch