1. Developmental Aspects

2. At birth, the skull bones are still incomplete The un-ossified remnants of fibrous membranes between skull bones are called fontanels

3. Developmental Aspects Fontanels – Allow for infant’s head to be slightly compressed during birth – Allows for growth of brain of fetus and infant

4. Developmental Aspects A baby’s pulse may be felt in fontanels – – Fontanel means little fountain

5. 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 1 st year

6. Developmental Aspects Fetal Skull Bones such as the mandible and maxilla are unfused in fetal skeleton – fuse by about 2 years Figure 7.33

7. At birth, the cranium is huge relative to the face Mandible and maxilla are short - but lengthen with age Developmental Aspects Growth Rates Figure 7.34

8. 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

9. 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

10. 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

11. 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.

12. 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

13. Intervertebral discs become thin, less hydrated, and less elastic Risk of disc herniation increases Developmental Aspects: Old Age

14. 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

15. 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

16. Our skeleton is the protector and supporter of other body systems All systems are connected

17. 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

18. Our integumentary system provides vitamin D needed for proper calcium absorption Skeletal and Integumentary Systems

19. Skeletal system protects brain and spinal cord and provides calcium ions needed for neural function Skeletal and Nervous Systems

20. 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

21. 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

22. Skeletal system protects lungs with ribs Respiratory system provides oxygen and disposes of carbon dioxide Skeletal and Respiratory Systems

23. Digestive system provides nutrients needed for bone health and growth Skeletal and Digestive Systems

24. Urinary system activates vitamin D and disposes of nitrogenous wastes Skeletal and Urinary Systems

25. Quiz – Next time! Study Guide