Asymmetrical Tonic Neck Reflex

Definition

The asymmetrical tonic neck reflex (ATNR) is a primitive reflex found in newborn humans, but normally vanishes around six months of age.

When the face is turned to one side, the arm and leg on the side to which the face is turned extend and the arm and leg on the opposite side bend.

It is also known as the "fencing reflex" because of the characteristic position of the infant's arms and head, which resembles that of a classically trained fencer.

Source: http://en.wikipedia.org/wiki/Asymmetrical_tonic_neck_reflex