SKELETAL SYSTEM

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SKELETAL SYSTEM
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Functions of Bones

• Support hard framework that supports and
  anchors body bones of legs act as pillars to
• Protection fused bones of the skull provide a
  snug enclosure for the brain vertebrae surround
  the spinal cord rib cage protects vital organs
• Movement skeletal muscles attach to bones by
  tendons and act as levers to move the body
• Storage bone matrix (calcium, phosphorus,
  potassium, sodium, sulfur, magnesium, copper)
  deposits and withdrawals are constant
• Blood cell formation hematopoiesis occurs
  within the marrow cavities of certain bones

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Bone Markings

• Projections
• Tuberosity large, rounded projection that may
  be roughened
• Crest Narrow ridge of bone
• Trochanter Very large, blunt, irregularly
  shaped process (only on the femur)
• Spine sharp, slender, often pointed projection
• Process any bony prominence

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Bone Markings (ctd.)

• Projections That Help Form Joints
• Facet smooth, nearly flat, articular surface
• Condyle rounded articular projection
• Ramus Arm-like bar of bone

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Bone Markings (ctd.)

• Depressions and Openings
• Meatus canal-like passageway
• Sinus Cavity within a bone filled with air and
  lined with mucous membrane
• Fossa Shallow, basin-like depression in a bone
  often serving as an articular surface
• Fissure Narrow, slit-like opening
• Foramen Round or oval opening through a bone

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Bone Fractures, Development, and Degeneration
http//www.youtube.com/watch?vMz2UuhbtrwY
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Bone Fractures

• Fracturebreak in a bone
• Types of bone fractures
• Closed (simple) fracturebreak that does not
  penetrate the skin
• Open (compound) fracturebroken bone penetrates
  through the skin
• Bone fractures are treated by reduction and
  immobilization

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Common Types of Fractures
Table 5.2
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Stages in the Healing of a Bone Fracture
Step 1 Hematoma (blood-filled swelling) is
formed
Figure 5.5, step 1
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Stages in the Healing of a Bone Fracture
Step 2 Break is splinted by fibrocartilage to
form a callus
Figure 5.5, step 2
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Stages in the Healing of a Bone Fracture
Step 3 Fibrocartilage callus is replaced by a
bony callus
Figure 5.5, step 3
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Stages in the Healing of a Bone Fracture
Step 4 Bony callus is remodeled to form a
permanent patch (spongy bone to compact bone)
Figure 5.5, step 4
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Skeletal Changes Throughout Life

• Ossification Centers in a 12-week-old Fetus

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Skeletal Changes Throughout Life

• Fetus
• Long bones are formed of hyaline cartilage
• Flat bones begin as fibrous membranes
• Flat and long bone models are converted to bone
• Birth
• Fontanels remain until around age 2

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Bone Growth (Ossification)

• Bones are remodeled and lengthened until growth
  stops
• Bones are remodeled in response to two factors
• Blood calcium levels
• Pull of gravity and muscles on the skeleton
• Bones grow in width (called appositional growth)

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Long Bone Formation and Growth
Figure 5.4a
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Long Bone Formation and Growth
Figure 5.4b
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The Fetal Skull

• The fetal skull is large compared to the infants
  total body length
• Fontanelsfibrous membranes connecting the
  cranial bones
• Allow the brain to grow
• Convert to bone within 24 months (2 years) after
  birth

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The Fetal Skull
Figure 5.13a
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The Fetal Skull
Figure 5.13b
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Skeletal Changes Throughout Life

• Adolescence
• Epiphyseal plates become ossified and long bone
  growth ends. These plates become an Epiphyseal
  line and can be seen on an X-ray.
• Size of cranium in relationship to body
• 2 years oldskull is larger in proportion to the
  body compared to that of an adult
• 8 or 9 years oldskull is near adult size and
  proportion
• Between ages 6 and 11, the face grows out from
  the skull

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Skeletal Changes Throughout Life
Figure 5.33a
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Skeletal Changes Throughout Life

• Osteoporosis
• Bone-thinning disease afflicting
• 50 of women over age 65
• 20 of men over age 70
• Disease makes bones fragile and bones can easily
  fracture
• Vertebral collapse results in kyphosis (also
  known as Dowagers Hump)
• Estrogen aids in health and normal density of a
  female skeleton

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