Bell Work 1. What do muscles do for the body? 2. What does the word voluntary mean? 3. What is a tendon? 4. What is meant by perpendicular? 5. Where would we find cardiac muscle? 6. What is a striation? 7. What does endo- mean again?

Muscle Types There are three muscle types: ◦ Skeletal ◦ Cardiac ◦ Smooth The ability of a muscle to shorten depends on two types of myofilaments Skeletal and smooth are elongated and therefore are referred to as muscle fibers Anytime you see the following prefixes, you are dealing with a muscle ◦ Myo- ◦ Mys- ◦ Sarco-

Skeletal Muscle Composed of skeletal muscle fibers Also known as striated (striped) muscle and voluntary muscle They are cigar shaped, multinucleated, and large (some are nearly a foot in length) Can contract rapidly with great force, but tire easily and need to rest after periods of activity

Skeletal Muscle Parts Endomysium – delicate connective tissue sheath that surrounds the muscle Fascicle – a bundle of muscle fibers Perimysium – Courser membrane that covers the fascicle. Epimysium – An even tougher cover that surrounds multiple fascicles. This covers the entire muscle and blends into either a ◦ Tendon – strong, cordlike material that connects the muscle to bones ◦ Aponeuroses – Attaches muscle indirectly to bone, cartilage, or other connective tissues

Smooth Muscle No striations Involuntary Spindle shaped with a single nucleus, arranged in sheets Usually arranged in two layers running in different directions (think perpendicular) Found in the walls of hollow visceral organs (stomach, bladder, respiratory passages) and is used to propel substances along the tract

Cardiac Muscle Found only in the heart It is striated, but involuntary They are branching cells joined at special junctions called intercalated discs Cushioned by small amounts of soft connective tissue and arranged in spiral or figure 8 shaped bundles Usually controlled by an internal pacemaker, but can also be influenced hormones and the nervous system

Muscle Function Producing Movement Maintain Posture Stabilizing Joints Generating Heat