Voluntary Movements of Infancy Chapter 11 McGraw-Hill/Irwin © 2012 McGraw-Hill Companies. All Rights Reserved.

11-2 “Voluntary movement is the ultimate expression in the striated muscle of the integrated effects of a host of cortical and subcortical facilitory and inhibitory influences”

11-3 Categorizing the Movements Voluntary movement groups Stability Head control, upright posture Locomotion Crawling, creeping, walking Manipulation Reaching, grasping, releasing

11-4 Categorizing the Movements Cephalocaudal pattern of development Head control Upper body control Lower body control

11-5 Stability ~ Head Control Voluntary movements begin at the head Control is evident by the end of the 1 st month Month 2: infant elevates head when prone Months 2-3: infant positions head from left to right or right to left when prone Month 5: infant elevates head when supine

11-6 Stability ~ Head Control

11-7 Stability ~ Body Control Chest elevation Segmented rolling back to front (vice versa) Crawling Ability to maintain upright posture frees the hands and arms for reaching and grasping

11-8 Voluntary Control of the Body

11-9 Stability ~ Body Control 3 monthsTries to roll from supine to prone; maintains sitting position 5 monthsSits when holding external supporting objects 6 monthsRolls from supine to prone position; maintains standing position when assisted 7 monthsAchieves sitting position from prone or supine position 8 monthsSits alone; rolls from prone to supine position 9-10 monthsPulls self to standing position 12 monthsStands unassisted

11-10 Locomotion ~ Prone Locomotion evolves from children gaining the ability to position their bodies for movement from one location in space to another

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11-12 Locomotion ~ Prone Crawling Precedes creeping Inefficient, highly variable arm and leg movements intended to propel the body forward Body is dragged Creeping Contralateral or homolateral pattern More efficient form of prone locomotion Body is elevated

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11-14 Locomotion ~ Prone Initial crawling Creeping Elevates trunk slightly Forward arm extension/flexion Leg flexion occasionally creates backward crawling

11-15 Locomotion ~ Upright Walking ~ the culmination of the acquisition of voluntary movement There is little evidence demonstrating that early walking will accelerate or refine future skill performance

11-16 Upright Locomotion Stair Climbing

11-17 Locomotion ~ Upright 7 monthsCrawling with slight elevation of trunk; occasional forward movement 7-8 monthsInitial crawling 9-12Creeping; creeping upstairs 8 monthsWalks with considerable assistance 10 monthsWalks laterally around furniture 11 monthsWalks when led 12 monthsWalks unassisted

11-18 Manipulation ~ Reaching, Grasping, Releasing Use of the hands enables children to gather information about their environment in a new way Recall that early manipulation is reflexive Palmar grasp reflex

11-19 Manipulation ~ Reaching, Grasping, Releasing Phase IPhase II Simultaneous reaching and grasping Differentiated reaching and grasping One-handed reachingTwo-handed reaching Visual initiation of the reach Visual initiation and guidance of the reach Visual control of the graspTactile control of the grasp

11-20 Manipulation ~ Reaching, Grasping, Releasing BirthPhase I reaching 1 monthPhase I reaching disappears 4 monthsPhase I reaching reappears 4-5 monthsUnable to receive multiple toys 5-6 monthsThumb used to oppose fingers in grasping 6 monthsReceives two toys while storing one toy in opposite hand 6-8 monthsReceives two toys while storing one toy in opposite hand

11-21 Manipulation ~ Reaching, Grasping, Releasing 9 monthsAdjusts arm and hand tension to object’s weight after grasping 9-10 months Thumb can oppose one finger in grasping 9-11 months Receives three toys; stores first two toys on lap or chair 12 monthsAdjusts arm and hand tension upon repeatedly receiving the same object months Receives three or more toys and crosses midline to hand toys to other person 18 monthsReleases objects with relative ease; anticipates arm and hand tension for repeated presentation of same object; expects unknown long objects to weigh more than short objects

11-22 Anticipation and Object Control in Reaching and Grasping By 18 months, infants exhibit anticipation Given the same object, repeatedly, infants display awareness that an object weighs the same Anticipation is not always accurate Expects unknown long object to weigh more that short object Anticipation and strength of grip develop over several years (2 years to 9 years)

11-23 Bimanual Control Complementary use of two hands to achieve a goal (receiving toys) is evident at 6-8 months

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