APA 3121 lec 4 early motor development

Two categories of newborn movements

Infantile reflexes and random or spontaneous movements.

Infantile reflexes

Involuntary, stereotypical movement responses to specific stimuli.

Random or spontaneous movements

Infant movements that occur without any apparent stimulation.

Subcortical areas in newborns

Control infantile reflexes and life-sustaining processes like breathing and heart rate.

Estimated number of major infant reflexes

Approximately 27 major infant reflexes.

Timeline of most infantile reflexes

Suppressed by 6 months of age; few are observable after the first year.

Importance of infant reflexes

Stimulates CNS and muscles; serves as a diagnostic tool for neurological maturity.

Three main types of infantile reflexes

Primitive reflexes, postural reactions, and locomotor reflexes.

Primitive reflexes

Associated with survival and protection; functional prenatally and suppressed around 3-4 months.

Postural reactions

Reactions to gravitational forces and equilibrium changes to maintain appropriate posture.

Locomotor reflexes

Resemble later voluntary locomotor movements; suppressed by month 5 or 6.

Sucking reflex trigger and timeline

Elicited by lip touch; evident in 4-month fetus and lasts until 6-9 months.

Rooting (search) reflex

Activated by light cheek touch, turning head toward stimulus; persists until 9th month.

Moro reflex

Startle/fall response causing arms and legs to extend outward; disappears by 3rd month.

Startle reflex

Appears at about 7 months; response is to flex arms and legs.

Palmar grasp reflex

Fingers fold tightly around an object placed in the hand; suppressed by 4 months.

Palmar grasp reflex peak strength

Present by 7th fetal month, peaks about 2 weeks after birth, then weakens.

Tonic neck reflex timeline and forms

Appears at about 7 fetal months and disappears by 5 months of age; has asymmetric and symmetric forms.

Asymmetric tonic neck reflex

Supine position and head turn triggers fencer's on guard position: limbs extend on face side and flex on opposite side.

Symmetric tonic neck reflex

Semi-standing position with head tipped backward extends neck/arms and flexes legs; tipping forward does the reverse.

Babkin (palmar-mandibular) reflex

Elicited by pressure to both palms, causing mouth to open, eyes to close, neck to flex, and head to tilt forward; disappears by 3rd month.

Babinski reflex

Elicited by stimulating the sole of the foot, causing the infant to fan out and extend its toes; suppressed by 4th month.

Plantar grasp reflex

Toes contract or flex as if attempting to grasp an object; persists through the first year of life.

Postural reactions overview

Gravity reflexes that help infants automatically maintain posture in a changing environment; appear after 2 months.

Head and body righting reflex

Basis for future voluntary rolling movements; turning the body in supine position causes the head and body to follow.

Labyrinthine righting reflex

Enables infant to maintain an upright body posture; appears around 2 months.

Labyrinthine righting timeline

Becomes stronger during the first year and normally disappears by 12 months.

Pull-up reaction

Involuntary attempt to stay upright when tipped; appears around 3 months.

Parachute reaction

Appears around 4 months; provides protective and supportive movements during sudden drops.

Parachute propping milestones

Sideward propping appears around 6 months; backward propping at 10-12 months.

Crawling reflex

Observed from birth; disappears by 4th month and builds muscle tone for voluntary crawling.

Stepping reflex

Elicited by holding infant upright with feet touching a flat surface; persists through 4th month.

Locomotor reflex: Swimming

Elicited during second week by holding infant horizontally in water; responds with rhythmic swimming movements; disappears by 4th month.

Primitive reflex modification

Primitive reflexes start to weaken or become modified after about 2 weeks.

Reflex adaptation example

Infants learn to adapt reflexes to modify movement outcomes, such as faster sucking leading to a faster milk supply.

Deviations from typical reflex patterns

Can reflect a pathological condition by exhibiting a reflex when not expected, or showing weak/no response when expected.

Babinski sign after head injury

A positive Babinski sign indicates the infantile reflex has returned, most likely pointing to an injury to the CNS.

Caution in reflex assessment

Individual, environmental, and task constraints mean infants develop differently without necessarily having a pathological condition.

Pathological warning sign for reflexes

Only when a reflex persists for several months past the average might it constitute a warning sign of pathology.

Structural purpose of reflexes

Reflect the structure of the nervous system and the way humans are wired.

Functional purpose of reflexes

Exist to help the infant survive—to eat, breathe, and grasp.

Applied purpose of reflexes

Suggest a role in future volitional movements, allowing the infant to practice coordinated limb movements beforehand.

Direct relationship view of reflex behavior

Assumes stimulation positively affects later voluntary control and that resembling reflexes must disappear before voluntary behavior occurs.

Indirect relationship view of reflex behavior

Postural and locomotor reflexes become supportive elements; they do not disappear but are suppressed and integrated into a hierarchy.

Spontaneous movements definition

Repetitive motions appearing without known stimuli; considered transitional behaviors before goal-oriented actions.

Spontaneous movement timeline

Observed as early as the 10th fetal week and peak between 6-10 months of age.

Abnormal spontaneous movements

Persistent rocking, waving, and non-purposeful spontaneous movements are considered abnormal in older children and adults.

Supine kicking coordination

Movements are rhythmical and coordinated, resembling adult walking step positioning and muscle activity, though infant timing is more variable.