Bones & Muscles

How many bones does the human skeleton contain?

206

Functions of the skeletal system Gives shape & support Protects internal organs Moves muscles Forms blood cells Stores calcium and phosphorous

Periosteum: soft, thin, covers and protects the bone Compact Bone: Hard, outer surface. Can heal itself when broken Spongy Bone: Porous, contains blood vessels, nerves Marrow: manufactures red blood cells Bone Cross Section

Skeletal System is divided into two parts

Axial Skeleton Skull (protects the brain). Ribs ( protect lungs, and heart). Spinal column (houses and protects the spinal cord).

Appendicular Skeleton Legs Pelvis Arms Shoulders

Types of Joints Immovable Skull Pelvis Movable Pivot Ball & socket Hinge Gliding

Types of Joints Ball and Socket Joint Bone with a rounded end that fits into a cuplike cavity on another bone

Ball & Socket: Shoulders and Hips Allows arms and hips to move in any direction Can move in a full 360 degrees

Types of Joints Pivot Joint One bone rotates in a ring of another bone that does not move

Pivot Joints: First two neck vertebrae & joint beneath elbow Moves in a semicircle motion by twisting against each other

Types of Joints Hinge Joint Back-and- forth movement like hinges on a door

Hinged: Elbows & Knees Move like hinges on a door Limited movement Can only swing back and forth

Type of Joints Gliding Joint One part of a bone slides over another bone

Gliding Joints: Spine, Wrists, Ankles Slide against each other in a gliding motion Gives your wrists and ankles lots of freedom

Immoveable joints are located in the skull and pelvis.

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How do muscles work

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Muscle Fiber Muscle Myofibril Inside a Muscle