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Developmental Aspects
Developmental Aspects
• At birth, the skull bones are still incomplete • The un-ossified remnants of
fibrous membranes between skull bones are called fontanels
Developmental Aspects
• Fontanels–Allow for infant’s head to be slightly compressed during birth–Allows for growth of brain of fetus and infant
Developmental Aspects
• A baby’s pulse may be felt in fontanels – –Fontanel means little fountain
Developmental Aspects• The large
diamond shaped fontanel called anterior fontanel is soft up to 2 years old.
• Other fontanels are replaced by bone by the end of 1st year
Developmental AspectsFetal Skull
• Bones such as the mandible and maxilla are unfused in fetal skeleton –fuse by about 2 years
Figure 7.33
• At birth, the cranium is huge relative to the face
• Mandible and maxilla are short - but lengthen with age
Developmental AspectsGrowth Rates
Figure 7.34
• By 9 months, the cranium is half of its adult size
• By 8 or 9 years, cranium has almost reached adult proportions
• Between 6 and 13, face grows more rapidly to adult proportions
• Only thoracic and sacral curvatures are present at birth
• The primary curvatures are convex posteriorly, causing the infant spine to arch like a four-legged animal
Developmental Aspects: Spinal Curvature
• Secondary curvatures – cervical and lumbar – are convex anteriorly and are associated with the child’s development–Cervical at 3 months when infant starts to raise head, and lumbar at 12 months when baby starts to walk
Developmental Aspects: Spinal Curvature
Growth Rates
• At birth, the head and trunk are about 1 ½ times as long as the lower limbs
• The arms and legs grow at a faster rate than the head and trunk, leading to adult proportions, so…
• By 10, the head and trunk are approximately the same height as the lower limbs.
Growth Rates
• During puberty, female pelvis broadens
• During puberty, male skeleton becomes more robust
• Once adult height is reached, skeleton changes very little until old age
• Intervertebral discs become thin, less hydrated, and less elastic
• Risk of disc herniation increases
Developmental Aspects: Old Age
• Loss of stature by several centimeters is common after age 55
• Further shortening can be produced by osteoporosis or by kyphosis
• Costal cartilages ossify causing the thorax to become rigid
Developmental Aspects: Old Age
• All bones lose mass – cranial bones lose less mass than most, but changes in facial contours with age are common
• As bones become more porous, they are more likely to fracture – especially the vertebrae and the neck of the femur
Developmental Aspects: Old Age
Our skeleton is the protector and
supporter of other body systems
All systems are connected
Skeletal and Muscular Systems
• Without our skeletal system, our muscles would be almost useless
• Muscle pull on bones increases bone strength and viability, and helps determine bone shape
• Skeletal system provides levers for our muscles and ionic calcium for muscle activity
• Our integumentary system provides vitamin D needed for proper calcium absorption
Skeletal and Integumentary Systems
• Skeletal system protects brain and spinal cord and provides calcium ions needed for neural function
Skeletal and Nervous Systems
• Endocrine system provides hormones that regulate uptake and release of calcium frm bone and hormones that promote long bone growth and maturation
Skeletal and Endocrine Systems
• Bone marrow cavities provide site for blood cell formation
• Cardiovascular system delivers nutrients and oxygen to bones and carries away wastes
Skeletal and Cardiovascular Systems
• Skeletal system protects lungs with ribs
• Respiratory system provides oxygen and disposes of carbon dioxide
Skeletal and Respiratory Systems
• Digestive system provides nutrients needed for bone health and growth
Skeletal and Digestive Systems
• Urinary system activates vitamin D and disposes of nitrogenous wastes
Skeletal and Urinary Systems
Quiz – Next time!
Study Guide
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