Growth and Development: Sequence of Motor Development

body systems and organs arise from 3 main germ layers, what are they?

ectoderm

mesoderm

endoderm

what gestational week does most early organ system formation occur by?

16

when does essential maturation for survival begin? what forms at this time?

week 24

pulmonary surfactant

what occurs at weeks 26-29?

pulmonary vasculature is able to participate in gas exchange and CNS is capable of controlling respiration

birth before ___ weeks of gestation leads to exceedingly low chance of survival

22

pervivable period where survival is possible with intensive care in NICU

22-25 weeks

relevance of premature birth to PTs

infants born at edge of viability have a higher risk of long-term motor/cognitive/sensory impairment --> early developmental surveillance and PT becomes highly important

primitive reflexes

automatic, stereotyped motor responses to specific sensory stimuli that are present at birth

what does the presence of primitive reflexes indicate

signals are traveling from the brainstem/spinal cord outward

important marker of neurological health throughout the lifespan

how do we elicit the rooting reflex? what should occur?

stroke infants cheek

infant turns head toward stimulated side and opens mouth

when should the rooting reflex integrate (go away)

around 1 year

how do we elicit the sucking reflex? what should we see?

touch roof of infant's mouth

rhythmic sucking pattern

sucking reflex works with ___ reflex to coordinate ___

rooting

early feeding

what elicits the moro reflex? what should we see? what is the purpose?

dropping head and neck backwards, sudden loud noise, abrupt temp change

arms/legs extend outwards, fingers open, limbs flex and pull back in

protective response to move away from threats

when do we become concerned if the moro reflex is still present

6 months

how do we elicit the tonic labyrinthine reflex (TLR)? what should we see?

move the head and neck fwd and bkwd relative to the trunk

when the head moves towards the chest, arms and legs bend and when it moves back, arms and legs straighten

when should the TLR integrate (go away) by

6-9 months

how do we elicit the asymmetrical tonic neck reflex (ATNR)? what should we see?

turning infant's head to one side while they are on their back

arm and leg on side that head is facing towards straighten while arm and leg on the other side bend (fencer posture)

purpose of ATNR? when do we get concerned if it persists?

aids in birthing process, initiation of reciprocal crawling

6 months

what does retention of primitive reflexes beyond the expected age indicate

cortex is not adequately inhibiting brainstem level reflexes, could indicate cerebral palsy/some other UMN conditions

what does diminished/absent reflexes in infancy indicate

early hypotonia/decreased neurological responsiveness indicator

what may cause primitive reflexes to reappear in adults

UMN lesion

what do righting reactions do

automatically orient head and trunk in upright/aligned position relative to gravity and each other

help us maintain posture as BOS constantly shifts

what is head righting? when does it onset? when is it integrated?

orientation of head in space so that eyes and mouth remain in horizontal plane regardless of body position

2.5-6 months (doesn't complete until ~10 months of age when head/neck control improves)

maintained throughout adult life

how do we measure/track head righting

standardized muscle scales for head/neck control strength

what are parachute reactions

protective extension reactions that automatically extend limbs to catch the body and prevent injury when there is LOb

parachute reactions emerge from integrated input from ___

vestibular, somatosensory, and visual systems

describe forward parachute reaction

how do we assess it?

when does it emerge?

child extends arms, head, and fingers outwards

hold infant upright w/ hands around waist and plunge downwards toward a flat surface

describe sideways parachute reaction

how do we assess it?

when does it emerge?

child reaches out and extends w/ arm opposite the push

child is sitting to start, push on one shoulder

7-8 months

describe backward parachute reaction

how do we assess it?

when does it emerge?

child extends both arms back and takes weight onto extended arms

push sitting child backward bruh

9-10 months

what are equilibrium reactions? how do they differ from protective reactions?

set of automatic postural adjustments that allow the body to maintain/regain balance

protective reactions are a RESPONSE to LOB while equilibrium reactions are proactive and continuous adjustments to muscle tone/body position

types of equilibrium reactions in the order they develop

prone, sitting, quadruped, standing

what does the systems model of postural development say

postural control doesn't occur all at once, emerges as multiple sensory systems progressively map as more muscles are needed for control (neck first --> trunk --> legs)

describe early sensorimotor mapping

visual, somatosensory, and vestibular systems each individually connect to neck muscles for early head control

they then combine into multisensory control of the head and later extend down to trunk/leg muscles

what do we see with sensorimotor mapping as children mature?

reliance on vision declines and the somatosensory system becomes increasingly dominant, we begin to see active hip strategies for standing balance

T/F: there is a fixed sequence of motor development milestones

F, motor development follows recurring organizational principles that explain how control is gained over the body

cephalocaudal development

development in a head-to-feet direction (head control before shoulder before trunk and so on)

T/F: control of head doesn't need to be fully perfected before lower regions begin to develop

T, stages overlap

proximal to distal development

stability develops proximally first (trunk, shoulders) and provides a postural base for distal segments to develop fine, controlled movement

flexion, extension, flexion development

fetus is in physiological flexion d/t confines of uterus

after birth, gravity's influence and increasing extensor tone allows for increased active extension against gravity

around 4-6 months infant develops active, controlled antigravity flexion

define postural stability

postural control to hold a body segment steady

define postural mobility

ability to move a body segment through space

asymmetry --> symmetry --> controlled asymmetry development

newborns are initially asymmetrical d/t reflexes like ATNR dominating their posture (asymmetry)

by 3-4 month, infants develop ability to hold symmetrical midline posture (symmetry)

by 5-6 months infants can voluntarily move in and out of symmetry while maintaining postural control (controlled asymmetry)

define dissociation

ability to move one body segment independently of another

rotation definition

movement of one body part around a fixed axis

what do dissociation and rotation both depend on

prior establishment of midline stability and controlled asymmetry

define weight bearing

ability of body part to resist/support weight

define weight shifting

shifting of body weight from one supporting body part to another, required for movement to occur