Developmental Aspects of the Skeleton

• Birth to adulthood


  -First "long bones" of a fetus are hyaline cartilage

  -Earliest "flat bones" of the fetal skull are fibrous membranes

  -As fetus grows, all bone models are converted to bone
• fetal skull


  -Frontanels are fibrous membranes connecting the cranial bones

  a.)Known as "soft spots"

  b.) Allow skull compression during birth

  c.)Allow the brain to grow during later pregnancy and infancy

  d.) Usually ossify by 2 years of age

  
• Growth of cranium after birth is related to brain growth


  Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways
• Size of cranium in relationship to body

  -2 years old: skull is three-fourths the size of adult skull

  -8 or 9 years old: skull is near adult in size and proportion

  -between ages 6 and 11, the face grows out from the skull

  
• skeletal changes


  -at birth, head & trunk are proportionately much longer than the lower limbs
• during puberty


  a.) Female pelvis broadens

  b.) Entire male skeleton becomes more robust
• By the end of adolescence:

  Epiphyseal plates become fully ossified
• older adults: Osteoporosis


  -Bone thinning disease afflicting:

  a.)50% of women over age 65

  b.)20% of men over age 70

  
• disease


  makes bones fragile, and bones can easily fracture
• Vertebral collapse results in


  kyphosis (also known as dowager's hump)

  
• Estrogen


  aids in health and normal density of a female skeleton