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# Joints - **Immovable joints** - do not allow movement - **Movable joints** - allow angular or rotary movements - **Partially movable joints** - allow slight movement - **Ligament** - Connects bones together # Types of joints - **Pivot joint** - Connects your head to the first vertebra in your ba...

# Joints - **Immovable joints** - do not allow movement - **Movable joints** - allow angular or rotary movements - **Partially movable joints** - allow slight movement - **Ligament** - Connects bones together # Types of joints - **Pivot joint** - Connects your head to the first vertebra in your backbone. It allows you to turn your head from side to side. - **Gliding joint** - Allows movement in many directions as the bones slide along each other. Your wrists and ankles contain gliding joints. - **Ball-and-socket joint** - Allows movement in all directions. Your shoulders and hips are ball-and-socket joints. - **Hinge joint** - Allows bending and straightening movements. Your knees and elbows are hinge joints. # Muscular System - Humans have about 600 muscles - Allows body movement; gives form and shape to the body # 3 Types of Muscle Tissue - **Cardiac muscle cells** - are located on the walls of the heart, appear striated, and are under involuntary control. - **Smooth muscle fibers** - are located in walls of hollow visceral organs, except the heart, appear spindle-shaped, and are also under involuntary control. - **Skeletal muscle fibers** - occur in muscles which are attached to the skeleton. They are striated in appearance and are under voluntary control.