a.k.a. The Musculoskeletal System

Muscular & Skeletal Systems

The Skeletal System

BonesProvide support for

the body

Form the body’s shape

Very lightweight, but strong enough to support body weight

206 bones in the body

Inside a BoneCompact bone – the solid,

hard outside part of the bone

Cancellous bone – spongy, inside the compact bone

Bone marrow – inside of the bone; where most of the blood cells are made (make a connection to another system)

Between the BonesLigaments – long,

fibrous straps that connect bones to other bones

Cartilage – flexible, rubbery substance; supports bones and protects them when they rub against each other

Types of BonesShort bones – chunky, wide bones; feet and

wrists

Long bones – a bone that is significantly longer than it is wide; arm and leg bones

Flat bones – plate-like bones, have a flat shape; ribs and shoulder blades

Irregular bones – have odd shapes and don’t fit into any other category, vertebrae

The Muscular System

MusclesMuscles pulls on the

joints, allowing us to move

Help the body perform other functions necessary for life, such as digesting food (make another connection here)

More than 650 muscles – half of a person’s body weight

3 types of muscle…

Skeletal Muscleattached to bone, mostly in

the legs, arms, abdomen, chest, neck, and face

Striated muscles (made up of fibers that have horizontal stripes)

Hold the skeleton together, give the body shape and help it with everyday movements

Voluntary (you can control their movements)

Smooth MuscleFound in the stomach

and small intestines; blood vessels (more connections here)

Looks smooth, not striated

Involuntary (you don’t control the movements, they are controlled by the nervous system automatically)

Cardiac MuscleFound in the heart

walls of the heart's chambers are composed almost entirely of muscle fibers

Involuntary (you don’t control the movements, they are controlled by the nervous system automatically)

JointsAllow our bodies to move in many ways

Classified by their range of movement (3 types)

Immovable (fibrous) joints don’t movedome of the skullTeeth in the jaw bone

Partially movable (cartilaginous) joints move a littleSpine (linked by cartilage)

Freely movable (synovial) jointsMove in many directionsFilled with synovial fluid

Hinge joints move in one directionElbow, knee

Pivot joints allow a rotating or twisting motionNeck, wrist

Ball-and-socket joints allow the greatest freedom of movementHip, shoulder

MovementTendons – connects bones

to the skeletal muscles

Muscle cells – only cells in the body that can shorten (contract)

Flexor – muscle that causes a joint to bend when it contracts

Extensor – muscle that causes a joint to straighten when it contracts

For more information check out…http://kidshealth.org/

teen/your_body/body_basics/bones_muscles_joints.html#