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
muscle.html
Muscle Fiber Muscle Myofibril Inside a Muscle