Motor Development

Summary of important motor milestones

Overview of motor development

Motor development involves function and myelination of neurons, development of proprioception, and muscular strength.

• Disorders in neuronal functions that lead to delay or inability to attain motor milestones (or regression)
  • Cerebral palsy
  • Traumatic or Hypoxic/Ischemic brain injury
  • Rett syndrome
• Myelination disorders that lead to delay or inability to attain motor milestones (or regression)
  • Niemann-Pick
  • Tay-Sachs
  • Krabbe disease
  • Gaucher disease
  • Metachromatic leukodystrophy
• Disorders of muscular strength that lead to delay or inability to attain motor milestones (or regression)
  • Muscular dystrophy
• What is meant by the term developmental coordination disorder
  • This is the acquisition of motor skills below that which is expected at a given chronoigical age, interfering with daily life
  • Signs and symptoms: clumsiness and incoordination
  • Not otherwise explained by an intellectual disability or neuromuscular condition affecting movement

Motor development

• Neonate
  • Tends to lay in flexed position; will turn head from side to side
  • Some head sagging on horizontal suspension (but neonate should not be hypotonic)
  • All primitive reflexes are present (Moro, grasp, rooting, tonic neck, etc.)
  • By 1 month of age should raise head off table (head sagging decreased)
  • When head is manipulated infants will not maintain contact (”doll’s eyes”)
  • Should reattain birthweight by 2 weeks of age, and grow 30g/day until 4 months
• 2 months
  • Head lag gone (head and trunk held in same plane on horizontal suspension)
  • Should be able to hold head steady while sitting in lap
  • Should be able to raise head slightly when lying in prone position (tummy time is important to develop neck tone)
• 4 months of age
  • Infant should be able to lift head above plane when held in horizontal suspension
  • Infant should be able to grasp objects like a rattle (and may reach for objects held above him/her as visual acuity improves)
  • Primitive reflexes may begin to disappear (may manipulate objects with both hands as palmar grasp reflex disappears, able to inspect hands at midline – hand obsessed)
  • Infants show more purposeful motor activity
  • Growth slows to 20 g/day until 1 year of age; birthweight should have doubled
• 6 months of age
  • Infants should be able to sit up without support
  • May be able to roll over and crawl
  • Primitive reflexes should be gone
  • Infant should be able to transfer objects from hand to hand
• 8 months of age
  • Should be able to sit up straight without support
  • Infant should be able to crawl and roll over
  • Pincer grasp develops
  • Infant is able to walk with assistance (holding one or both hands/arms)
  • Baby will often **“cruise” (**helps baby develop muscle strength for walking)
• 12 months of age
  • Birthweight should have tripled by first birthday; length increased by 50%; head circumference increased by 10cm
  • Baby is able to stand on his/her own
  • Baby is cruising by this point (able to walk with one hand held)
  • Able to turn pages of a book (hand eye coordination)
• 16 months of age
  • Child should be walking by 15 months of age, and is able to run (albeit awkwardly)
  • Child is able to crawl up a stair(s)
  • Should be able to scribble with a crayon
  • Classically, by 16 months, the child should be able to build a tower of 2 or 3 blocks (reflects gross and fine motor development)
• 18 months of age (1.5 years)
  • Child should be able to run by this point
  • Should be able to walk up and down stairs with hands held (with alternating steps)
  • Often will be able to sit on a small, child-sized chair
  • Classically, should be able to build a tower of 4 blocks
• 24 months of age (2 years old)
  • Development of coordination
  • Should be able to jump in place
  • Often able to insert small objects into holes
  • Classically, should be able to build a 7 block tower
• 30 months of age (2.5 years)
  • Birth weight should have quadrupled
  • Child should be able to properly ascend stairs with alternating feet
  • Child should be able to stand on one foot
• 3 years of age
  • Child should be able to descend the stairs with alternating feet
  • Should be able to properly draw or copy a circle
  • Left– or right-handedness is developed
  • Should be able to ride a tricycle if trained
• 4 years
  • Child should be able to hop in place
  • Should be able to overhand throw
  • Should be able to copy a square