1. Chapter 7 Skeletal System
Hole’s Human Anatomy and Physiology Twelfth Edition Shier w Butler w Lewis
Chapter 7
Skeletal System
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2. 7.1: Introduction
Human skeleton initially cartilages and fibrous membranes
Hyaline cartilage is the most abundant cartilage
By age 25 the skeleton is completely hardened growth ceases
206 bones make up the adult skeleton (20% of body mass)
80 bones of the axial skeleton
126 bones of the appendicular skeleton

3. 7.2: Bone Structure
Bones of the skeletal system vary greatly in size and shape
There is similarity in structure, development, and function

4. Support, Protection, and Movement
Support, Movement & Protection
Gives shape to head, etc.
Supports body’s weight
Protects lungs, etc.
Bones and muscles interact
When limbs or body parts move

5. Bone Classification Bone Classification: Long Bones Short Bones
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Bone Classification:
(b)
Long Bones
Short Bones
Sesamoid Bones
Flat Bones
Irregular Bones
Wormian Bones
(c)
(d)
(a)
(e)

6. Parts of a Long Bone Epiphysis Diaphysis Metaphysis Compact bone
Distal
Proximal
Diaphysis
Metaphysis
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Epiphyseal plates
Articular cartilage
Proximal
Spongy bone
epiphysis
Space containing red marrow
Compact bone
Spongy bone
Endosteum
Compact bone
Medullary cavity
Articular cartilage
Periosteum
Endosteum Y
ellow marrow
Periosteum
Diaphysis
Medullary cavity
Trabeculae
Bone marrow
Red marrow and yellow marrow
Distal
epiphysis
Femur

7. Microscopic Structure
Bone cells are called osteocytes
Osteocytes transport nutrients and wastes
The extracellular matrix of bone is largely collagen and inorganic salts
Collagen gives bone resilience
Inorganic salts make bone hard

8. Compact Bone Osteon aka Haversian System Central canal
Perforating canal aka Volkmann’s canal
Osteocytes
Lamellae
Lacunae
Bone matrix
Canaliculi
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Osteon
Compact
bone
Central canal
containing blood
vessels and nerves
Endosteum
Spongy
bone
Periosteum
Nerve
Blood
vessels
Pores
Central
canal
Perforating
canal
Compact
bone
Nerve
Blood
vessels
Nerve
Trabeculae
Bone matrix
Canaliculus
Osteocyte
Lacuna
(space)

9. a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.
Spongy Bone
Spongy bone is aka cancellous bone
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Spongy
bone
Compact
bone
(a)
Remnant of
epiphyseal plate
Spongy bone
Compact bone
(b)
(c)
Spongy
bone
Compact
bone
a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.

10. 7.3: Bone Development and Growth
Parts of the skeletal system begin to develop during the first few weeks of prenatal development
Bones replace existing connective tissue in one of two ways:
As intramembranous bones
As endchondral bones

11. Intramembranous Bones
These bones originate within sheetlike layers of connective tissues
They are the broad, flat bones
Skull bones (except mandible)
Are known as intramembranous bones

12. Endochondral Bones Endochondral Bones Bones begin as hyaline cartilage
Form models for future bones
These are most bones of the skeleton
Are known as endochondral bones

13. Endochondral Ossification
Hyaline cartilage model
Primary ossification center
Secondary ossification centers
Epiphyseal plate
Osteoblasts vs. osteoclasts
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Articular
cartilage
Remnants of
epiphyseal
plates
Secondary
ossification
center
Cartilaginous
model
Developing
periosteum
Compact bone
developing
Spongy
bone
Epiphyseal
plates
Blood
vessel
Medullary
cavity
Medullary
cavity
Medullary
cavity
Compact
bone
Remnant of
epiphyseal
plate
Epiphyseal
plate
Calcified
cartilage
Primary
ossification
center
Secondary
ossification
center
Spongy
bone
Articular
cartilage
(a)
(b)
(c)
(d)
(e)
(f)

14. Animation: Bone Growth in Width
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15. Growth at the Epiphyseal Plate
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
First layer of cells
Closest to the end of epiphysis
Resting cells
Anchors epiphyseal plate to epiphysis
Bone tissue
of epiphysis 1
Zone of
resting
cartilage 2
Zone of
proliferating
cartilage 3
Zone of
hypertrophic
cartilage
Second layer of cells
Many rows of young cells
Undergoing mitosis 4
Zone of
calcified
cartilage
Ossified
bone of
diaphysis
(a)
(b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

16. Growth at the Epiphyseal Plate
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Third layer of cells
Older cells
Left behind when new cells appear
Cells enlarging and becoming calcified
Bone tissue
of epiphysis 1
Zone of
resting
cartilage 2
Zone of
proliferating
cartilage 3
Zone of
hypertrophic
cartilage
Fourth layer of cells
Thin
Dead cells
Calcified extracellular matrix 4
Zone of
calcified
cartilage
Ossified
bone of
diaphysis
(a)
(b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

17. Homeostasis of Bone Tissue
Bone Resorption – action of osteoclasts and parathyroid hormone aka parathormone aka PTH
Bone Deposition – action of osteoblasts and calcitonin
Occurs by direction of the thyroid and parathyroid glands
Figure 7.13 page 205
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Developing medullary
cavity
Osteoclast
© Biophoto Associates/Photo Researchers, Inc.

18. Factors Affecting Bone Development, Growth and Repair
Deficiency of Vitamin A – retards bone development
Deficiency of Vitamin C – results in fragile bones
Deficiency of Vitamin D – rickets, osteomalacia
Insufficient Growth Hormone – dwarfism
Excessive Growth Hormone – gigantism, acromegaly
Insufficient Thyroid Hormone – delays bone growth
Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates
Physical Stress – stimulates bone growth

19. 7.1 Clinical Application
Fractures
Page 202

20. Blood Cell Formation Blood Cell Formation Also known as hematopoiesis
Occurs in the red bone marrow

21. Inorganic Salt Storage
Calcium
Phosphate
Magnesium
Sodium
Potassium

22. Osteopenia and Osteoporosis: Preventing “Fragility Fractures”
7.2 Clinical Application
Osteopenia and Osteoporosis: Preventing “Fragility Fractures”
Page 204