1. Chapter 5 The Skeletal System
Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 5 The Skeletal System
The word skeleton comes from the Greek word meaning “dried-up body.”
Our internal framework is designed and engineered to be strong and light.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

2. The Skeletal System Parts of the skeletal system
Bones (skeleton)
Joints
Cartilages
Ligaments
Divided into two divisions
Axial skeleton
Appendicular skeleton
The axial skeleton includes bones that form the longitudinal axis of the body.
The appendicular skeleton includes the bones of the limbs and girdles.
Slide 5.1
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3. 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
LEARN THESE FUNCTIONS WITH ONE EXCEPTION!!!
Movement is not considered a function of the skeletal system, but one of the muscles. It is included here only to show that they help the body with locomotion.
STORAGE: Fat is stored in the internal cavities of bones.
Bones also store mineral – the most important being calcium and phosphorus.
Hormones regulate the amount of calcium deposited and withdrawn.
Slide 5.2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

4. Functions of Bones Support of the body Protection of soft organs
Internal framework that supports and anchors all soft organs
Bones of the legs act as pillars to support the body trunk
Protection of soft organs
LEARN THESE FUNCTIONS WITH ONE EXCEPTION!!!
Movement is not considered a function of the skeletal system, but one of the muscles. It is included here only to show that they help the body with locomotion.
STORAGE: Fat is stored in the internal cavities of bones.
Bones also store mineral – the most important being calcium and phosphorus.
Hormones regulate the amount of calcium deposited and withdrawn.
Skull enclosures the brain
The vertebrae surround the spinal cord and the rib cage protects vital organs of the thorax
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

5. Functions of Bones Storage of minerals and fats
Movement due to attached skeletal muscles
Skeletal muscles use the bones as levers to move the body
Bones of the legs act as pillars to support the body trunk.
Storage of minerals and fats
LEARN THESE FUNCTIONS WITH ONE EXCEPTION!!!
Movement is not considered a function of the skeletal system, but one of the muscles. It is included here only to show that they help the body with locomotion.
STORAGE: Fat is stored in the internal cavities of bones.
Bones also store mineral – the most important being calcium and phosphorus.
Hormones regulate the amount of calcium deposited and withdrawn.
Calcium (essential in nervous system)
Phosphorus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

6. Bones of the Human Body The skeleton has 206 bones
Two basic types of bone tissue
Compact bone
Dense and homogeneous
Spongy bone
Small needle-like pieces of bone
Many open spaces
You need to remember the two basic types of bone tissue!
Compact bone is very dense and looks smooth.
Spongy bone is as the slide mentions.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

7. Classification of Bones
Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Example: Bones of the limbs: Femur, humerus
Basically, all the bones of the limbs except the wrist and ankle bones are long bones.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Classification of Bones
Short bones
Generally cube-shape
Contain mostly spongy bone
Example: Sesamoid bones (form within tendons), pattela or kneecap
Bones of the wrist and ankle: Carpals, tarsals.
Remember that they are cube-shaped!
The bones of the wrist and ankle are short bones.
Sesamoid bones, found within tendons, are a special type of short bone.
The patella is a sesamoid bone.
Slide 5.4b
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9. Classification of Bones on the Basis of Shape
Figure 5.1
Slide 5.4c
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10. Classification of Bones
Flat bones
Thin and flattened
Usually curved
Two thin layers of compact bone around a layer of spongy bone
Examples: Skull, ribs, sternum (breastbone)
The layers of compact bone around a layer of spongy bone resemble a sandwich.
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11. Classification of Bones
Irregular bones
Do not fit into other bone classification categories
Irregular shape
Example: Vertebrae and hip
The bones of the spinal column and the hip fall into this group.
Slide 5.5b
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12. Classification of Bones on the Basis of Shape
Remember…you need to remember these four classifications of bones.
Figure 5.1
Slide 5.5c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings