muscles overview

skeletal muscle

voluntary movement; striated. move body by pulling on bones

cardiac muscle

involuntary movement within body; striated. moves blood in heart

smooth muscle

involuntary movement within body. moves digestive material and controls movement of blood in circulatory system

properties of muscle

excitability, contractility, extensibility, elasticity

excitability (responsiveness)

ability to receive and respond to a stimulus. muscle fiber responds to a nerve impulse

contractility

ability of cells to shorten upon stimulation

extensibility

ability of a muscle to be stretched

elasticity

ability of a muscle to recoil to its resting length after contraction

functions of skeletal muscle

• produces movement

• maintains posture and body position

• supports soft tissues

• guard body entrances and exits (sphincters)

• maintain body temp (muscles release heat)

• store nutrients

skeletal muscles contain…

skeletal muscle tissue (primary), connective tissue, blood vessels, and nerves

3 layers of skeletal muscle

epimysium, perimysium, endomysium

epimysium

layer of collagen fibers that surrounds the entire muscle. considered a deep facia; separates muscle from surrounding tissue

perimysium

surrounds muscle fiber bundles (fascicles). contains collagen fibers, elastic fibers, blood vessels, and nerves

endomysium

surrounds individual muscles cells (muscle fibers). contains capillary networks, myosatellite cells (stem cells), and nerve fibers

how is a tendon (bundle) or aponeurosis (sheet) formed?

collagen fibers of epimysium, perimysium, and endomysium coming together at ends of muscles; attach skeletal muscles to bone

skeletal muscle blood supply has…

extensive vascular networks that deliver oxygen and nutrients, and remove metabolic wastes