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