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