What holds your joints together and keeps them connected as you move? Bones come together at joints. Joints are wrapped with ligaments that hold the joint together. Cartilage, a soft type of protein, acts as padding and helps to decrease friction where bones connect. Damaged cartilage causes pain and arthritis!

Arthritis: damaged cartilage in joints

Types of Joints Joints are places where bones connect. Joints increase skeletal flexibility FFF (Form Follows Function) The configuration of a joint (form) determines the degree and direction of possible motion (function).

Immovable joints: no motion between the bones Cranium sutures

Slightly movable/semi-movable joints Ribs to sternum Provide flexibility during breathing

Freely Movable Joint types Hinge joint : An angle change in one plane Elbow Knee Fingers Like a door hinge, opening and closing

Freely Movable Joint types Ball and Socket Joint: circular rotational motion Hip Shoulder Like a “joy stick” Provides maximum mobility

Freely Movable Joint types Pivot Joint Side to side rotation, like turning a doorknob Elbow ( mily.net/skeleton/AR M.MOV) mily.net/skeleton/AR M.MOV Neck

Freely Movable Joint types: Glide Joint Slide back and forth across connecting surface Metacarpal/metatarsal (hands, feet) vertebrae

Reading review: bone types Long bones Arms, legs Short bones Feet, hands Irregular bones spine Flat bones Ribs, skull

Reading review: Joints improve body flexibility Immovable: Skull and pelvis Slightly movable: ribs to sternum Freely movable: large range of motion Hinge: angular movement Elbow, knee Pivot: side to side rotational motion elbow, neck Ball and socket: circular rotation Shoulder, hip Glide: small back and forth slide Spine, wrists, ankles

questions What questions do you have about bones and bone growth? Growth plates Osgood schlatters Bone, tendon, ligament deal...when does that happen? What do other organisms use?

WHY? Bird bones are easier to break. Why? Some fish, like sharks and skates, do not have calcium in their bones –instead, their bones are made entirely of cartilage protein-–like the cartilage in your nose and ears. Why is this an advantage? Why is it a disadvantage?