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MUSCLE SYSTEMSTRUCTURE OF MUSCLESFUNCTIONMovement in the body sustaining posture and body position. There are three types of muscle tissues: skeletal, cardiac, and smooth.Excitability: Electric gradient Contraction: Shorten Elongate: RelaxSkeletal MusclesSmooth MusclesCardiacMusclesVoluntarymuscles thatwork in pairs tomoveComposed ofmuscle fibers(cells) thatare boundtogether inparallelbundles. Alsoknown asstriatedmuscle dueto theirstrippedappearance.Involuntary musclesthat are found in thewalls of internal organssuch as the stomach,intestines and bloodvessels.Smooth muscletissue (visceraltissue) isnonstriated. Alsofound in sphinctersor valves thatcontrol variousopenings throughthe bodyInvoluntarymuscle that isfound in theheartMuscles Fascicle Fiber Myofibril SarcomereMYOSIN (thick) & ACTIN (thin)Note:Where two bones meet is called a joint, or articulation. Ligaments (dense fibrous connective tissue) hold bones together. Muscles also help to stabilizethe joint. When muscles contract, they move a joint. A muscle must cross a joint in order to move bones. Tendons (dense fibrous connective tissue) attach muscles to bones. The bone that moves is called the insertion of the muscle; the bone that doesn’t move during the contraction is called the origin. Some muscles have more than one origin and/or insertion, and some (such as some thigh muscles) cross more than one joint. In these cases, the movement is more