Chapter 10: Movement and

Forces10.1 The skeletal system provides movement and

protection10.2 The muscular system makes movement possible

10.3 Muscles exert forces10.4 Bones and joints at as levers

The skeleton is the body’s framework

• Skeletal system• includes bones, ligaments, cartilage, and

tendons• anchors the body’s movement, provides

support, and protects the internal organs

The skeleton is the body’s framework

• Bones: are classified by their shape:• Long bones • longer than wide• Found in the arms and legs

• Short bones• As long as wide• Bones in the wrists and ankles

• Flat bones• Thin and flat or slightly curved• Ribcage and skull

• Irregular bones• Shaped differently than long,

short, or flat• Spine and skull

The skeleton is the body’s framework

• Skeleton• Provides the body’s shape• Works with other systems to allow movement• Two main divisions:• Axial skeleton (& Appendicular skeleton) • central part• Includes skull, spinal column, ribs• The bones in the appendicular skeleton are attached to the

axial skeleton

• What functions do vertebrae perform?• They protect the spinal cord and

support the cranium and other bones.• How many bones are in the ankle and

foot? • 26• Which division of the skeleton

includes the ankle and foot bones? • Appendicular skeleton• What is the only bone in the skull that

can move?• lower jaw

Divisions of the Skeleton - Axial Skeleton

• Line straight down your back ~ axis• Sit, stand, twist…about your axis• Axis ~ axial skeleton• Support and protection• Top: cranium – surrounds the brain• Cranium + bones in face (jaw, cheek…) = skull• Skull connects to the spinal column

• Spinal column (backbone): main portion of axial skeleton• Made of vertebrae – bones stacked one on top of another

• Rib bones and sternum

Divisions of the Skeleton – Appendicular skeleton

• Bones that function to allow movement• Arms and legs• Upper part:• bones of the shoulders, arms, and hand

• Lower part:• Bones in hips, legs, and feet• Bear all the body’s weight while standing• Leg bones: strongest in your body

Bones are living tissue• Not solid – have spaces inside –

lighter in weight• Made of cells and minerals• Contain blood vessels• Make, maintains, and break down

bone tissue• Minerals (ex: calcium) give bones

structure and stiffness• Bones:• support and protect the body• produce and store blood cells• store calcium for the body

Bones are living tissue – two types of tissue

• Spongy bone• Strong• Lightweight• Mineral part looks like a web• Supports bones like beams support a building

• Can compress slightly• Near the end of long bones: absorb forces• Red bone marrow: produces blood cells• New blood cells travel from marrow blood vessels in bone

• Blood brings nutrients to bone cells / carries away waste

• Compact bone• Tough outer layer, surrounds spongy bone• Basic supportive tissue• Dense, organized in layers - STRONG

• Why is the compact bone able to give the bone strength? • It is dense.• How does bone receive nourishment?• Blood vessels bring in nutrients.• Where are red blood cells formed? • in the red bone marrow

Joints connect parts of the skeletal system

• Joint: a place where two bones in the skeletal system meet• allow the body to be flexible• Three types: immovable, slightly movable, and

freely movable

Immovable and Slightly Movable Joints

• Immovable joint • locks bones together like puzzle pieces• Skull bones are connected by immovable joints• Inside the cranium, the joints are called sutures

(appear stitched - no space between)

• Slightly movable joint• Able to flex a little• Ex: ribs connected to sternum • No space between bone, but bones connected by

cartilage, so can move slightly• Cartilage: tough but flexible connective tissue• Ex: outer ear, nose, cushions between vertebrae, shark!

Freely Movable Joints• Allow you to bend and move• Most of the joints in your body• Wrist, knee, elbow• Bones are separated by a cavity containing fluid• Ligaments (tissue) hold bones together at movable joints• Materials between bones (ex: fluid, cartilage) keeps them from

rubbing together• Tendons (tissue) connect muscles to bones (but are not part

of the joint)• These all work together with muscles movement!

Types of joints (6) – based on type of movement

• Hinge Joint• Ex: elbow and knee• Arm movement: angle between upper and lower arm

decreases = angular movement

• Ball-and-Socket Joint• Ex: hip and shoulder• Pitchers, swimmers, quarterback, shotput…• Shoulder can rotate in a circle • Rounded part of one bone fits into a cup-shaped part of

another

• Pivot Joint• Ex: elbow, connecting the radius and ulna• Rotational movement – rotate side to side (turn a

doorknob)

Types of joints (6) – based on type of movement

• Gliding Joint• Ex: some joints in ankles and wrists, vertebrae• Small flat bones sliding or gliding over one another• Limited movement

• Saddle Joint• ONE ex: thumb• Like a joystick – forward and backward, side to side• More limited than ball-and-socket joint

• Ellipsoid Joint• Ex: in hands and feet at base of each finger and toe• Allow bones to move like a hinge in different directions, but not

rotate

Different joints work together different movements!

• Each motion had a limited range of movement. The types and ranges of movement differed.

• Different joints allow rotational movements, angular movements, and gliding movements.

Real World ExampleSometimes people get diseases thatmake it painful to move their joints. Onesuch disease is bursitis. Bursas are fluidfilledsacs at the joints that cushionmovement. Occasionally, bursas becomeinflamed, making it harder for musclesand tendons to slide over bones.Movement is often painful. Bursitis canoccur when people repeat the samemotion over and over again. Tenniselbow is one form of bursitis. Bursitis canalso result from heavy pressure on a joint.Resting the joint and applying ice mayhelp reduce the inflammation.Teacher DemoDo the following demonstration to showhow important cartilage and synovialfluid, a kind of lubricant, are to makingjoints work smoothly. The cartilage andfluid reduce friction and wear on thebones. Ask students to watch as youpress and slide a wooden block that hasbeen sanded—not varnished or polished—along a flat wooden board. Youwill feel friction along the way. Next,wrap both the board and block in plasticbags. The plastic acts like cartilage as yourub the two pieces of wood together.Now, rub cooking oil on the plastic bagsand run the block along the board. Thecooking oil performs like synovial fluid inthe body does and makes it much easierto slide the two pieces of wood againsteach other.Ongoing AssessmentExplain how joints allow movement.

How does position affect support?

• PROCEDURE1. Hold the bag in your hand and keep your arm

straight. Move the bag up and down.2. Move the handles of the bag over your elbow.

Again hold your arm straight and move the bag up and down.

3. Move the bag to the upper part of your arm and repeat the procedure.

• WHAT DO YOU THINK?• At which position was it easiest to move the

bag?• At which position did the bag move the farthest?

• nearest to the shoulder• in the hand