Primitive reflexes

General

Brainstem-mediated, complex, automatic movement patterns that commence as early as the 25th week of gestation.

Fully present at birth in term infants, and disappear with CNS maturation (when voluntary motor activity and thus cortical inhibition emerges).

Infants with cerebral palsy have been known to demonstrate persistence of primitive reflexes or a delay in their disappearance.
Persistence of obligatory primitive reflexes beyond 12 months of age is an indicator of a poor prognosis regarding ambulation.

Plantar response:

Different types of responses have been elicited in infants, varying from flexor to extensor according to the intensity of the stimulus used but it is generally accepted and that extensor plantar response matures to flexor by the end of the first year in most normal infants.
Babinski sign refers to the extensor toe response observed in corticospinal tract pathology but there is ongoing debate as to whether a true Babinski sign (dorsiflexion of the great toe and fanning of the remaining toes) is present as a primitive reflex in infants where it is part of flexion withdrawal of the leg.

Reflex list

Reflex	Position	Method	Response	Age at Disappearance
Palmar grip	Supine	Placing the index finger in the palm of the infant	Flexion of fingers, fist-making	6 months
Plantar grip	Supine	Pressing a thumb against the sole just behind the toes	Flexion of toes	15 months
Galant	Prone	Scratching the skin of the infant's back from the shoulder downward, 2-3 cm lateral to the spinous processes	Incurvation of the trunk, with the concavity on the stimulated side	4 months
Asymmetric tonic neck	Supine	Rotation of the infant's head to one side for 15 s	Extension of the extremities on the chin side and flexion of those on the occipital side	3 months
Suprapubic extensor	Supine	Pressing the skin over the pubic bone with the fingers	Reflex extension of both lower extremities, with adduction and internal rotation into talipes equinus	4 weeks
Crossed extensor	Supine	Passive total flexion of one lower extremity	Extension of the other lower limb, with adduction and internal rotation into talipes equinus	6 weeks
Rossolimo	Supine	Light tapping of toes 2-4 at their plantar surfaces	Tonic flexion of the toes at the first metacarpophalangeal joint	4 weeks
Heel	Supine	Tapping on the heel with a hammer, with the infant's hip and knee joints flexed and the ankle joint in neutral position	Rapid reflex extension of the lower extremity in question	3 weeks
Moro (startle reflex)	Supine	Sudden head extension produced by a light drop of the head	Abduction followed by adduction and flexion of upper extremities	6 months
Babinski	Supine	Striking along the lateral aspect of the sole, extending from the heel to the head of the fifth metatarsal	Combined extensor response: simultaneous dorsiflexion of the great toe and fanning of the remaining toes	Presence abnormal always