The Skeletal System
• Parts of the skeletal system
• Bones (skeleton)
• Joints: hold bone together & mobility
• Cartilages:
• Ligaments & Tendons
• Divided into two divisions
• Axial skeleton
• Appendicular skeleton
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Slide 5.1
Functions of Bones
• Support of the body
• Protection of soft organs
• Movement due to attached skeletal
muscles
• Storage of minerals and fats
• Blood cell formation
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Slide 5.2
Bones of the Human Body
• The skeleton has 206 bones
• Two basic types of bone tissue
•Compact bone
•Homogeneous
•Spongy bone
•Small needle-like
pieces of bone
Figure 5.2b
•Many open spaces
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Slide 5.3
Classification of Bones
• Long bones
•Typically longer than wide
•Have a shaft with heads
at both ends
•Contain mostly compact bone
• Examples: Femur, humerus
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Slide 5.4a
Classification of Bones
• Short bones
•Generally cube-shape
•Contain mostly spongy bone
•Examples: Carpals, tarsals
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Slide 5.4b
Classification of Bones on the Basis
of Shape
Figure 5.1
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Slide 5.4c
Classification of Bones
• Flat bones
•Thin and flattened
•Usually curved
•Thin layers of compact bone
around a layer of spongy bone
•Examples: Skull, ribs, sternum
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Slide 5.5a
Classification of Bones
• Irregular bones
•Irregular shape
•Do not fit into other bone
classification categories
•Example: Vertebrae and hip
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Slide 5.5b
Gross Anatomy of a Long Bone
• Diaphysis
•Shaft
•Composed of
compact bone
• Epiphysis
•Ends of the bone
•Composed mostly
of spongy bone
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Figure 5.2a
Slide 5.6
Structures of a Long Bone
• Periosteum
• Outside covering
of the diaphysis
• Fibrous connective
tissue membrane
• Sharpey’s fibers
• Secure periosteum
to underlying bone
• Arteries
• Supply bone cells
with nutrients
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Figure 5.2c
Slide 5.7
Structures of a Long Bone
• Articular
cartilage
• Covers the
external surface of
the epiphyses
• Made of hyaline
cartilage
• Decreases friction
at joint surfaces
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2a
Slide 5.8a
Structures of a Long Bone
• Medullary cavity
• Cavity of the shaft
• Contains yellow
marrow (mostly fat)
in adults
• Contains red
marrow (for blood
cell formation) in
infants
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Figure 5.2a
Slide 5.8b
Bone Markings
• Sites of attachments for muscles,
tendons, and ligaments
• Passages for nerves and blood vessels
• Categories of bone markings
•Projections and processes – grow out
from the bone surface
•Depressions or cavities – indentations
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Slide 5.9
Microscopic Anatomy of Bone
• Osteon (Haversian System)
• A unit of bone
• Central (Haversian) canal
• Opening in the center of an osteon
• Carries blood vessels and nerves
• Perforating (Volkman’s) canal
• Canal perpendicular to the central canal
• Carries blood vessels and nerves
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Slide 5.10a
Microscopic Anatomy of Bone
Figure 5.3
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Slide 5.10b
Microscopic Anatomy of Bone
• Lacunae
• Cavities containing
bone cells
(osteocytes)
• Arranged in
concentric rings
• Lamellae
• Rings around the
central canal
• Sites of lacunae
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.3
Slide 5.11a
Microscopic Anatomy of Bone
• Canaliculi
•Tiny canals
• Radiate from the
central canal to
lacunae
•Form a
transport
system
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Figure 5.3
Slide 5.11b
Changes in the Human Skeleton
• In embryos, the skeleton is primarily
hyaline cartilage
• During development, much of this cartilage
is replaced by bone
• Cartilage remains in isolated areas
• Bridge of the nose
• Parts of ribs
• Joints
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Slide 5.12
Bone Growth
• Bones are remodeled and lengthened until
growth stops
• Epiphyseal plates allow for growth of long
bone during childhood
• New cartilage is continuously formed
• Older cartilage becomes ossified
• Cartilage is broken down
• Bone replaces cartilage
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Slide 5.13a
Long Bone Formation and Growth
Figure 5.4a
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Slide 5.14a
Long Bone Formation and Growth
Figure 5.4b
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Slide 5.14b
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
• Bone remodeling is a process by both
osteoblasts and osteoclasts
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Slide 5.15
Bone Fractures
• A break in a bone
Bone Fracture
Types
• 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
• Realignment of the bone
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Slide 5.16
Quiz on Types of Fractures
Repair of Bone Fractures
• Hematoma (blood-filled swelling) is
formed
• Break is splinted by fibrocartilage to form
a callus. Osteoclasts break down bone.
• Fibrocartilage callus is replaced by a bony
callus. Osteoblasts form bone and
become Osteocytes.
• Bony callus is remodeled to form a
permanent patch.
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Slide 5.18
Stages in the Healing of a Bone
Fracture
Figure 5.5
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Slide 5.19
Self-Care for Broken Bones
Check Out Dem Bones!
Facial Bones Quiz
Classification of Bones Quiz
Fetal Skull
• Adult skull is 1/8 body length (infant
is ¼)
• When born, skeleton is unfinished –
fontanels (soft spots)
• Largest are anterior and posterior
• Allow skull to compress in birth,
room for brain to grow
Paranasal Sinuses
• Functions of paranasal sinuses
• Lighten the skull
• Give resonance and amplification to
voice
Figure 5.10
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Slide 5.25b
Structural Classification of Joints
• Fibrous joints
• Generally immovable; bones connected
by fibrous tissue: sutures
• Cartilaginous joints
• Immovable or slightly moveable; bones
connected by cartilage: spine
• Synovial joints
• Freely moveable; have joint cavity with
synovial fluid: elbow, wrist
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Slide 5.45
Functional Classifications of Joints
• Synarthrosis
-immovable joint
• Amphiarthrosis
-a slightly movable joint
• Diarthrosis
-a freely movable joint
Let’s see the joints move.
• Don’t click on the cowboy, just hit next.
Moving Joints
Different Joint Structures
Figure 5.27d, e
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Slide 5.46
Structures Associated with the
Synovial Joint
• Bursae – flattened fibrous sacs
• Lined with synovial membranes
• Filled with synovial fluid
• Not actually part of the joint
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Slide 5.50
The Synovial Joint
Figure 5.28
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Slide 5.51
Types of Synovial Joints Based on
Shape
Figure 5.29a–c
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Slide 5.52a
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Slide 5.52b
Figure 5.29d–f
Types of Synovial Joints Based on
Shape
Types of Joints Quiz
Inflammatory Conditions Associated
with Joints
• Bursitis – inflammation of a bursa usually
caused by a blow or friction
• Tendonitis – inflammation of tendon
sheaths
• Arthritis – inflammatory or degenerative
diseases of joints
• Over 100 different types
• The most widespread crippling disease
in the United States
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Slide 5.53
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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.54a
Two types of arthritis explained.
• Click on both boxes
Rheumatoid Arthritis
Osteoarthritis
Gouty Arthritis (gout)
• Uric acid accumulates in blood and
deposited in soft tissues of joints –
painful attack of single joint (big toe)
• Males after 30, genetic
• Treatment – drugs, weight
management
Developmental Aspects
• Fetal development – flat and long
bones are converted to bone
• Birth – fontanels still remain for brain
growth up to 2 years
• Adolescence – epiphyseal plates of
long bones are ossified (quit growing)
Developmental Aspects
• Puberty – female pelvis broadens
for childbearing, male skeleton
becomes more robust
• Osteoporosis – loss of bone mass
leading to thin, fragile bones
• In women – menopause estrogen
deficiency, diet poor in Ca,
smoking, or inactivity
Osteoporosis
Normal
Osteoporosis
Herniated Disc
• Pressure on a disc ruptures the outer layer and
forces the soft center (nucleus pulposus) out,
which then puts pressure on a spinal nerve
• Most occur in lumbar region
Abnormalities of Spine
• Scoliosis – abnormal lateral
curvature, can result in having one
leg longer than the other
• Kyphosis (hunchback) – exaggerated
thoracic curve
• Lordosis (swayback) – exaggerated
lumbar curve
Scoliosis
Kyphosis
Lordosis