bone fractures, development, and degeneration
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Bone Fractures, Development, and Degeneration
http://www.youtube.com/watch?v=Mz2UuhbtrwY
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Bone Fractures
• Fracture—break in a bone• Types of bone fractures
– Closed (simple) fracture—break that does not penetrate the skin
– Open (compound) fracture—broken 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
Figure 5.5, step 1
Hematoma
Hematomaformation
Step 1: Hematoma (blood-filled swelling) is formed
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 2
Hematoma
Externalcallus
Newbloodvessels
Internalcallus(fibroustissue andcartilage)
Spongybonetrabecula
Hematomaformation
Fibrocartilagecallus formation
Step 2: Break is splinted by fibrocartilage to form a callus
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 3
Hematoma
Externalcallus
Bonycallus ofspongybone
Newbloodvessels
Internalcallus(fibroustissue andcartilage)
Spongybonetrabecula
Hematomaformation
Fibrocartilagecallus formation
Bony callusformation
Step 3: Fibrocartilage callus is replaced by a bony callus
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Stages in the Healing of a Bone Fracture
Figure 5.5, step 4
Hematoma
Externalcallus
Bonycallus ofspongybone
Healedfracture
Newbloodvessels
Internalcallus(fibroustissue andcartilage)
Spongybonetrabecula
Hematomaformation
Fibrocartilagecallus formation
Bony callusformation
Bone remodeling
Step 4: Bony callus is remodeled to form a permanent patch (spongy bone to compact bone)
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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
Bone startingto replacecartilage
Epiphysealplatecartilage
Articularcartilage
Spongybone
In a childIn a fetusIn an embryo
New boneforming
Growthin bonewidth
Growthin bonelength
Epiphysealplate cartilage
New boneforming
Bloodvessels
Hyalinecartilage
New center ofbone growth
Medullarycavity
Bone collar
Hyalinecartilagemodel
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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 infant’s total body length
• Fontanels—fibrous 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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Ossification Centers in a 12-week-old
Fetus
Figure 5.32
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Skeletal Changes Throughout Life
• Adolescence– Epiphyseal plates become ossified and long bone
growth ends
• Size of cranium in relationship to body– 2 years old—skull is larger in proportion to the
body compared to that of an adult– 8 or 9 years old—skull 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 Dowager’s Hump)
– Estrogen aids in health and normal density of a female skeleton
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