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

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Hormones regulate the amount of calcium deposited and withdrawn.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

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 Hormones regulate the amount of calcium deposited and withdrawn.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

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

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

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

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Bones on the Basis of Shape Figure 5.1 Slide 5.4c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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