Tonic Neck Reflexes

Published July 2, 2026 Read time 2 min read Readers 2

What is the “Tonic Neck Reflexes” used for?

There are both asymmetric and symmetric tonic neck reflexes. Of the two, the asymmetric form is tested more often.

The asymmetric tonic neck reflex is present at birth and normally disappears by 4 to 6 months of age.
The symmetric tonic neck reflex usually is present by 5 to 8 months of age.

To test the asymmetric tonic neck reflex, the infant is placed in the supine position with the head in midline.
To elicit the reflex, the infant’s head is turned to one side (without flexion), maintained in that position for 5 to 10 seconds by holding the chin over the shoulder, and then turned to the opposite side.
With a positive response, the arm on the side to which the chin is rotated becomes rigid and the elbow goes into extension (the leg on that side may also extend). On the opposite side (the “occiput” side), the arm (and sometimes the leg) goes into flexion. This is the classically described “fencer’s position.”
The grasp reflex may be more easily elicited on the flexion side.

The symmetric tonic neck reflex is tested with the infant resting in the prone position over the examiner’s knees (the quadriceps position).
When the head and neck are extended, the upper limbs extend (or extensor tone increases), whereas the lower limbs flex (or flexor tone increases).
When the head and neck are flexed, the upper limbs flex (or flexor tone increases) and the lower limbs extend (or extensor tone increases).

Its absence indicates flaccid paralysis or severe hypotonia.
The reflex is considered abnormal when it occurs every time it is evoked. In pathologic conditions, such as severe cerebral palsy, the reflex persists and may even increase. Increased extensor tone on the “chin” side and increased flexor tone on the “occiput” side may be the only findings when the positive response is weak.

If this reflex is absent, the infant will be unable to assume a four-point kneeling position.
There is no absolute time for its normal disappearance; however, it is often diminished or absent by 12 months of age.
Its persistence can interfere with alternating lower limb motion and prevent crawling or hinder ambulation.
It can also cause adduction and medial rotation, resulting in flexion gait patterns.