Download Spongy bone (diploë)

Chapter Opener 6
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Figure 6.1 The bones and cartilages of the human skeleton.
Cartilage in
external ear
Cartilage in
intervertebral
disc
Cartilages in
nose
Articular
cartilage
of a joint
Costal
cartilage
Epiglottis
Thyroid
cartilage
Cricoid
cartilage
Larynx
Trachea
Lung
Respiratory tube cartilages
in neck and thorax
Pubic
symphysis
Meniscus
(padlike cartilage
in knee joint)
Articular
cartilage of a joint
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Bones of skeleton
Axial skeleton
Appendicular skeleton
Cartilages
Hyaline cartilages
Elastic cartilages
Fibrocartilages
Figure 6.2 Classification of bones on the basis of shape.
Flat bone (sternum)
Long bone
(humerus)
Irregular bone (vertebra),
right lateral view
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Short bone (talus)
Figure 6.2a Classification of bones on the basis of shape.
Long bone
(humerus)
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Figure 6.2b Classification of bones on the basis of shape.
Irregular bone (vertebra),
right lateral view
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Figure 6.2c Classification of bones on the basis of shape.
Flat bone (sternum)
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Figure 6.2d Classification of bones on the basis of shape.
Short bone (talus)
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Figure 6.3 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone.
Spongy bone
(diploë)
Compact
bone
Trabeculae of
spongy bone
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Figure 6.4 The structure of a long bone (humerus of arm).
Articular
cartilage
Proximal
epiphysis
Compact bone
Spongy bone
Epiphyseal
line
Periosteum
Endosteum
Endosteum
Compact bone
Medullary
cavity (lined
by endosteum)
Diaphysis
Yellow
bone marrow
Compact bone
Periosteum
Perforating
(Sharpey’s)
fibers
Nutrient
arteries
Distal
epiphysis
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Figure 6.4a The structure of a long bone (humerus of arm).
Articular
cartilage
Proximal
epiphysis
Spongy bone
Epiphyseal
line
Periosteum
Compact bone
Medullary
cavity (lined
by endosteum)
Diaphysis
Distal
epiphysis
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Figure 6.4b The structure of a long bone (humerus of arm).
Articular
cartilage
Compact bone
Spongy bone
Endosteum
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Figure 6.4c The structure of a long bone (humerus of arm).
Endosteum
Yellow
bone marrow
Compact bone
Periosteum
Perforating
(Sharpey’s)
fibers
Nutrient
arteries
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Figure 6.5 Comparison of different types of bone cells.
Osteogenic cell
Stem cell
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Osteoblast
Matrix-synthesizing
cell responsible for
bone growth
Osteocyte
Mature bone cell
that monitors and
maintains the
mineralized bone
matrix
Osteoclast
Bone-resorbing cell
Figure 6.5a Comparison of different types of bone cells.
Osteogenic cell
Stem cell
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Figure 6.5b Comparison of different types of bone cells.
Osteoblast
Matrix-synthesizing
cell responsible for
bone growth
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Figure 6.5c Comparison of different types of bone cells.
Osteocyte
Mature bone cell
that monitors and
maintains the
mineralized bone
matrix
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Figure 6.5d Comparison of different types of bone cells.
Osteoclast
Bone-resorbing cell
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Table 6.1 Bone Markings (1 of 2)
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Table 6.1 Bone Markings (2 of 2)
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Figure 6.6 A single osteon.
Artery with
capillaries
Structures
in the
central
canal
Vein
Nerve fiber
Lamellae
Collagen
fibers
run in
different
directions
Twisting
force
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Figure 6.7 Microscopic anatomy of compact bone.
Compact bone Spongy bone
Central
(Haversian) canal
Perforating
(Volkmann’s) canal
Endosteum lining bony canals
and covering trabeculae
Osteon
(Haversian system)
Circumferential
lamellae
Lamellae
Nerve
Vein
Artery
Canaliculi
Osteocyte
in a lacuna
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Perforating (Sharpey’s) fibers
Periosteal blood vessel
Periosteum
Lamellae
Central
canal
Lacunae
Interstitial Lacuna
lamella
(with osteocyte)
Figure 6.7a Microscopic anatomy of compact bone.
Compact bone Spongy bone
Central
(Haversian) canal
Perforating
(Volkmann’s) canal
Endosteum lining bony canals
and covering trabeculae
Osteon
(Haversian system)
Circumferential
lamellae
Lamellae
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Perforating (Sharpey’s) fibers
Periosteal blood vessel
Periosteum
Figure 6.7b Microscopic anatomy of compact bone.
Nerve
Vein
Artery
Canaliculi
Osteocyte
in a lacuna
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Lamellae
Central
canal
Lacunae
Figure 6.7c Microscopic anatomy of compact bone.
Lamellae
Central
canal
Lacunae
Interstitial Lacuna
lamella
(with osteocyte)
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Figure 6.8 Endochondral ossification in a long bone.
Week 9
Month 3
Birth
Secondary
ossification
center
Epiphyseal
blood vessel
Area of
deteriorating
cartilage matrix
Hyaline
cartilage
Spongy
bone
formation
Bone collar
Primary
ossification
center
1 Bone collar
forms around the
diaphysis of the
hyaline cartilage
model.
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Childhood to
adolescence
Articular
cartilage
Spongy
bone
Epiphyseal
plate
cartilage
Medullary
cavity
Blood
vessel of
periosteal
bud
2 Cartilage in the
center of the
diaphysis calcifies
and then develops
cavities.
3 The periosteal
bud invades the
internal cavities
and spongy bone
forms.
4 The diaphysis
elongates and a
medullary cavity
forms. Secondary
ossification
centers appear in
the epiphyses.
5 The epiphyses
ossify. When
completed, hyaline
cartilage remains
only in the
epiphyseal plates
and articular
cartilages.
Figure 6.8 Endochondral ossification in a long bone. (1 of 5)
Week 9
Hyaline
cartilage
Bone collar
Primary
ossification
center
1 Bone collar forms around the
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diaphysis of the hyaline cartilage
model.
Figure 6.8 Endochondral ossification in a long bone. (2 of 5)
Area of deteriorating
cartilage matrix
2 Cartilage in the center
of the diaphysis calcifies
and then develops cavities.
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Figure 6.8 Endochondral ossification in a long bone. (3 of 5)
Month 3
Spongy
bone
formation
Blood
vessel of
periosteal
bud
3 The periosteal bud invades
the internal cavities and spongy
bone forms.
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Figure 6.8 Endochondral ossification in a long bone. (4 of 5)
Birth
Epiphyseal
blood vessel
Secondary
ossification
center
Medullary
cavity
4 The diaphysis elongates and a medullary cavity forms.
Secondary ossification centers appear in the epiphyses.
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Figure 6.8 Endochondral ossification in a long bone. (5 of 5)
Childhood to
adolescence
Articular
cartilage
Spongy
bone
Epiphyseal
plate
cartilage
The epiphyses ossify. When completed, hyaline cartilage
remains only in the epiphyseal plates and articular
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Inc.
cartilages.
5
Figure 6.9 Intramembranous ossification.
Mesenchymal
cell
Osteoblast
Collagen fibril
Osteoid
Ossification
center
Osteocyte
Newly
calcified
bone matrix
Osteoid
Osteoblast
1 Ossification centers appear in the fibrous
connective tissue membrane.
• Selected centrally located mesenchymal cells
cluster and differentiate into osteoblasts, forming an
ossification center that produces the first trabeculae of
spongy bone.
2 Osteoid is secreted within the fibrous membrane and
calcifies.
• Osteoblasts begin to secrete osteoid, which calcifies in a few days.
• Trapped osteoblasts become osteocytes.
Mesenchyme
condensing
to form the
periosteum
Trabeculae of
woven bone
Blood vessel
3 Woven bone and periosteum form.
• Accumulating osteoid is laid down between embryonic blood vessels in
a manner that results in a network (instead of concentric lamellae) of
trabeculae Called woven bone.
• Vascularized mesenchyme condenses on the external face of the woven
bone and becomes the periosteum.
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Fibrous
periosteum
Osteoblast
Plate of
compact bone
Diploë
(spongy bone)
cavities
contain red
marrow
4 Lamellar bone replaces woven bone, just deep to the
periosteum. Red marrow appears.
• Trabeculae just deep to the periosteum thicken. Mature lamellar
bone replaces them, forming compact bone plates.
• Spongy bone (diploë), consisting of distinct trabeculae, persists
internally and its vascular tissue becomes red marrow.
Figure 6.9 Intramembranous ossification. (1 of 4)
Mesenchymal cell
Collagen fibril
Ossification center
Osteoid
Osteoblast
1 Ossification centers appear in the fibrous connective
tissue membrane.
• Selected centrally located mesenchymal cells cluster and
differentiate into osteoblasts, forming an ossification center
that produces the first trabeculae of spongy bone.
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Figure 6.9 Intramembranous ossification. (2 of 4)
Osteoblast
Osteoid
Osteocyte
Newly calcified
bone matrix
2 Osteoid is secreted within the fibrous membrane and
calcifies.
• Osteoblasts begin to secrete osteoid, which calcifies in a few days.
• Trapped osteoblasts become osteocytes.
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Figure 6.9 Intramembranous ossification. (3 of 4)
Mesenchyme
condensing
to form the
periosteum
Trabeculae of
woven bone
Blood vessel
3 Woven bone and periosteum form.
• Accumulating osteoid is laid down between embryonic blood
vessels in a manner that results in a network (instead of
concentric lamellae) of trabeculae called woven bone.
• Vascularized mesenchyme condenses on the external face of
the woven bone and becomes the periosteum.
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Figure 6.9 Intramembranous ossification. (4 of 4)
Fibrous periosteum
Osteoblast
Plate of
compact bone
Diploë (spongy bone)
cavities contain red
marrow
4 Lamellar bone replaces woven bone, just deep to the
periosteum. Red marrow appears.
• Trabeculae just deep to the periosteum thicken. Mature
lamellar bone replaces them, forming compact bone plates.
• Spongy bone (diploë), consisting of distinct trabeculae,
persists internally and its vascular tissue becomes red marrow.
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Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate.
Resting zone
1 Proliferation zone
Cartilage cells undergo
mitosis.
2 Hypertrophic zone
Older cartilage cells
enlarge.
Calcified
cartilage spicule
Osteoblast
depositing bone
matrix
Osseous tissue
(bone) covering
cartilage spicules
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3 Calcification zone
Matrix calcifies; cartilage
cells die; matrix begins
deteriorating; blood
vessels invade
cavity.
4 Ossification zone
New bone forms.
Figure 6.11 Long bone growth and remodeling during youth.
Bone growth
Cartilage
grows here.
Bone
replaces
cartilage
here.
Cartilage
grows here.
Bone replaces
cartilage here.
Bone remodeling
Articular cartilage
Epiphyseal plate
Bone that was
here has been
resorbed.
Appositional
growth adds
bone here.
Bone that was
here has been
resorbed.
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Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels.
Calcium homeostasis of blood: 9–11 mg/100 ml
BALANCE
BALANCE
Stimulus
Falling blood
Ca2+ levels
Thyroid
gland
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood.
Parathyroid
glands
PTH
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Parathyroid
glands release
parathyroid
hormone (PTH).
Figure 6.13 Bone anatomy and bending stress.
Load here
(body weight)
Head of
femur
Compression
here
Tension
here
Point of
no stress
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Figure 6.14 Vigorous exercise can strengthen bone.
Crosssectional
dimension
of the
humerus
Added
bone matrix
counteracts
added stress
Serving arm
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Nonserving arm
Table 6.2 Common Types of Fractures (1 of 3)
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Table 6.2 Common Types of Fractures (2 of 3)
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Table 6.2 Common Types of Fractures (3 of 3)
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Figure 6.15 Stages in the healing of a bone fracture.
Hematoma
Internal
callus
(fibrous
tissue and
cartilage)
1 A hematoma forms.
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External
callus
Bony
callus of
spongy
bone
New
blood
vessels
Healed
fracture
Spongy
bone
trabecula
2 Fibrocartilaginous
callus forms.
3 Bony callus
forms.
4 Bone
remodeling
occurs.
Figure 6.15 Stages in the healing of a bone fracture. (1 of 4)
Hematoma
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1 A hematoma forms.
Figure 6.15 Stages in the healing of a bone fracture. (2 of 4)
External
callus
Internal
callus
(fibrous
tissue and
cartilage)
New
blood
vessels
Spongy
bone
trabecula
2 Fibrocartilaginous
callus forms.
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Figure 6.15 Stages in the healing of a bone fracture. (3 of 4)
Bony
callus of
spongy
bone
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3 Bony callus
forms.
Figure 6.15 Stages in the healing of a bone fracture. (4 of 4)
Healed
fracture
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4 Bone
remodeling
occurs.
Figure 6.16 The contrasting architecture of normal versus osteoporotic bone.
Normal bone
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Osteoporotic bone
Figure 6.16a The contrasting architecture of normal versus osteoporotic bone.
Normal bone
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Figure 6.16b The contrasting architecture of normal versus osteoporotic bone.
Osteoporotic bone
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Figure 6.17 Fetal primary ossification centers at 12 weeks.
Parietal
bone
Frontal
bone
of skull
Mandible
Occipital
bone
Clavicle
Scapula
Radius
Ulna
Humerus
Femur
Tibia
Ribs
Vertebra
Ilium
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System Connections 6.1
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