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 Aspects
Fetal Skull
• Bones such as
the mandible
and maxilla are
unfused in fetal
skeleton
–fuse by about
2 years
Figure 7.33
Developmental Aspects
Growth Rates
• At birth, the
cranium is huge
relative to the
face
• Mandible and
maxilla are
short - but
lengthen with
age
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
Developmental Aspects: Spinal
Curvature
• 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
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
Developmental Aspects:
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
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
Skeletal and Integumentary
Systems
• Our integumentary system provides
vitamin D needed for proper
calcium absorption
Skeletal and Nervous Systems
• Skeletal system protects brain and
spinal cord and provides calcium
ions needed for neural function
Skeletal and Endocrine 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 Cardiovascular
Systems
• Bone marrow cavities provide site
for blood cell formation
• Cardiovascular system delivers
nutrients and oxygen to bones and
carries away wastes
Skeletal and Respiratory
Systems
• Skeletal system protects lungs with
ribs
• Respiratory system provides oxygen
and disposes of carbon dioxide
Skeletal and Digestive Systems
• Digestive system provides nutrients
needed for bone health and growth
Skeletal and Urinary Systems
• Urinary system activates vitamin D
and disposes of nitrogenous wastes
Quiz – Next time!
Study Guide