PTA 230: typical motor development Birth to 3 months
Describe an asymmetric tonic neck reflex, seen when the baby turns the head to one side
The arm on the side to which the head is turned may extend and may allow the infant to see the hand *the other arm is flexed (fencing pos.)
The newborn's legs are flexed under the pelvis and prevent
contact of the pelvis with the supporting surface *unable to lift head from prone *birth to 3m0
Weight bearing through the arms and shoulders provide
proprioceptive feedback (greater sensory awareness to those structures) allows infant to view hands in prone *birth to 3mo
By 2-3 moths, eyes and hands are sufficiently linked to allow for
reaching grasping & shaking a rattle
During the primitive neck righting reflex, what motion is missing
separation of upper & lower trunk segments around the long axis of the body
When in supine position, the 1-3 month old will exhibit these random movements
Arm & leg movements *limbs remain flexed, never extending completely
What does a 3 month baby look like in prone
Upper trunk flexion weight bearing thru forearms Flat pelvis Hips externally rotated & abducted Knees flexed Feet Together (desensitization for future standing)
Being in prone promotes strengthening of spinal extensors, which allows the infant to
bring the arms under the body into a position to support himself on the forearms *birth to 3mo
The important stages of motor development in the first year of life are those associated with these months
even months 4, 6, 8, 10 and 12
By 3 months, forearm weight bearing helps initiate the 1st coordinated action between the
extensors (neck) flexors (shoulders) *helps build stability of the shoulder complex
Typical motor behavior of a 4 month old infant is characterized by
head control, support on arms and hands, and midline orientation.
By 3 months of age, the infant can
lift the head to 45° *maintain midline pos.
As neck & spinal extension develop and allow the infant to
lift the head to one side, to lift and turn the head, and then to lift the and hold the head in midline *birth to 3mo
During the first 3 months, while in supine the infants head is kept in this position
one side or the other *because neck muscles are not yet strong enough to maintain midline
Newborns assume a flexed posture regardless of their position because
physiologic flexor tone dominates at birth *ankle, knees, hips, elbows
Prior to 4 months of age, an infant pulled to sitting from supine will demonstrate this head/neck posture
the head lags behind the body, but attempts neck flexion *postural control of the head has not been established.
Primitive rolling may be seen, prior to 4 months, as the infant preforms this movement
the infant runs the head strongly to one side *body rotates as unit with head in same direction
the infant must wait for gravity to help lower the pelvis and for the neck muscles to strengthen to be able
to lift the head when in the prone, first unilaterally then bilaterally *birth to 3mo