Transcript Ossification and Fractures

Ossification Centers in a 12week-old Fetus
Figure 5.32
Types of Bone Cells
• Osteocytes—mature bone cells
• Osteoblasts—bone-forming cells
• Osteoclasts—bone-destroying cells
– Break down bone matrix for remodeling and
release of calcium in response to parathyroid
hormone
• Bone remodeling is performed by both
osteoblasts and osteoclasts
Articular
cartilage
Hyaline
cartilag
e
Spongy
bone
New center of
bone growth
New bone
forming
Epiphyseal
plate
cartilage
Growth
in bone
width
Medullary
cavity
Bone starting
to replace
cartilage
Growth
in bone
length
Blood
vessels
New bone
forming
Bone collar
Hyaline
cartilage
model
Epiphyseal
plate cartilage
Figure 5.4a, step 3
In an embryo
(a)
In a fetus
In a child
Articular
cartilage
Hyaline
cartilag
e
Spongy
bone
New center of
bone growth
New bone
forming
Epiphyseal
plate
cartilage
Growth
in bone
width
Medullary
cavity
Bone starting
to replace
cartilage
Growth
in bone
length
Blood
vessels
New bone
forming
Bone collar
Hyaline
cartilage
model
Epiphyseal
plate cartilage
Figure 5.4a, step 3
In an embryo
(a)
In a fetus
In a child
The Fetal Skull
Figure 5.13b
Skeletal Changes Throughout
Life
• Adolescence
– Epiphyseal plates become ossified and long
bone growth ends
• Size of cranium in relationship to body
Skeletal Changes Throughout
Life
Figure 5.33a
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
Dislocation of
the
glenohumeral
joint
Repair of Bone Fractures
• Hematoma (blood-filled swelling) is formed
• Break is splinted by fibrocartilage to form a
callus
• Fibrocartilage callus is replaced by a bony
callus
• Bony callus is remodeled to form a
permanent patch
Stages in the Healing of a Bone
Fracture
Hematoma
Hematoma
formation
Figure 5.5, step 1
Stages in the Healing of a Bone
Fracture
Hematoma
External
callus
Internal
callus
(fibrous
tissue and
cartilage)
New
blood
vessels
Spongy
bone
trabecula
Hematoma
formation
Fibrocartilage
callus formation
Figure 5.5, step 2
Stages in the Healing of a Bone
Fracture
Hematoma
External
callus
Internal
callus
(fibrous
tissue and
cartilage)
Bony
callus of
spongy
bone
New
blood
vessels
Spongy
bone
trabecula
Hematoma
formation
Fibrocartilage
callus formation
Bony callus
formation
Figure 5.5, step 3
Stages in the Healing of a Bone
Fracture
Hematoma
External
callus
Internal
callus
(fibrous
tissue and
cartilage)
Bony
callus of
spongy
bone
New
blood
vessels
Healed
fracture
Spongy
bone
trabecula
Hematoma
formation
Fibrocartilage
callus formation
Bony callus
formation
Bone remodeling
Figure 5.5, step 4
Inflammatory Conditions
Associated with Joints
• Bursitis—inflammation of a bursa usually
caused by a blow or friction
• Arthritis—inflammatory or degenerative
diseases of joints
– Over 100 different types
– The most widespread crippling disease in the
United States
Clinical Forms of Arthritis
• Osteoarthritis
– Most common chronic arthritis
– Probably related to normal aging processes
• Rheumatoid arthritis
– An autoimmune disease—the immune system
attacks the joints
– Symptoms begin with bilateral inflammation of
certain joints
– Often leads to deformities
Clinical Forms of Arthritis
• Gouty arthritis
– Inflammation of joints is caused by a
deposition of uric acid crystals from the blood
– Can usually be controlled with diet
The Vertebral Column
Figure 5.16
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
Skeletal Changes Throughout
Life
Figure 5.34
Skeletal Changes Throughout
Life
Figure 5.35