Can transform atp into mechanical energy which is capable of exerting force: dealing with physical movement. Excitability (responsiveness)- ability to receive and respond to stimuli. Each muscle receives a nerve, artery, and veins: nerves supplying every fiber of every consciously controlled muscle to control activity for fine-tuned movements. Contracting muscle fibers require huge amounts of oxygen and nutrient and waste products removed quickly. Each skeletal muscle/ muscle fiber is covered in ct. Sheaths from external to internal: epimysium- dense irregular ct surrounding entire muscle, may bled with fascia, perimysium- fibrous ct surrounding fascicles, endomysium- fine areolar ct surrounding muscle fiber. Muscles span joints and attach to bones. Muscles attach to bone in at least two places: insertion- attachment to moveable bone, origin- attachment to immovable or less movable bone. Attachments can be direct or indirect: direct (fleshy)- epimysium fused to periosteum of bone or perichondrium of cartilage, indirect- ct wrappings extend beyond muscle as ropelike tendon or sheet like aponeurosis.