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