Symmetrical Tonic Neck Reflex (STNR)

The Symmetrical Tonic Neck Reflex (STNR) typically appears around 6-9 months of age and is usually integrated by 9-11 months of age. This reflex is activated when the infant’s head is flexed or extended, causing the arms and legs to respond in a coordinated manner—when the head is flexed forward, the arms bend, and the legs straighten; when the head is extended backward, the arms straighten, and the legs bend. The STNR plays a crucial role in helping the baby learn to crawl by enabling the separation of upper and lower body movements. This reflex is essential for transitioning from lying to sitting and for the development of crawling, which is important for hand-eye coordination and overall motor development.

If the STNR remains unintegrated or becomes reactivated in adulthood, it can lead to several motor and postural challenges. Adults with an unintegrated STNR may experience difficulties with activities that require coordinated movements between the upper and lower body, such as swimming, running, or even sitting for extended periods. An unintegrated STNR can lead to poor posture, particularly a tendency to slouch or hunch over, as the body struggles to maintain a balanced position when the head is flexed or extended. 

This reflex can also affect the ability to focus visually, as the connection between head movement and limb response may interfere with tasks that require stable eye-hand coordination, such as reading or typing. In some cases, persistent STNR can contribute to difficulty in tasks requiring smooth transitions between movements, leading to clumsiness or discomfort during physical activities.

• Appears: 6-9 months
• Integrated by: 9-11 months
• Muscles Involved: Neck flexors and extensors, Shoulder girdle muscles, Abdominals, Quadriceps
• Extraordinary Meridians: Du, Yang Wei
• The Du channel governs the spine and central axis, essential for the coordinated movements of the upper and lower body in STNR.
• The Yang Wei channel influences the lateral body and supports these movements.
• Acupuncture Points: DU14 (Dazhui), GB21 (Jianjing), ST36 (Zusanli)
• Myofascial Line: Deep Front Line (DFL)

Cranial Nerves: Accessory nerve (CN XI)