THE MUSCULAR SYSTEM Chapters 10 & 11

Objectives Describe the arrangement of fascicles in the various types of muscles. Identify different muscles in the axial and appendicular skeletons. Describe what happens during aging in the muscular system.

Muscle Organization and Function Muscles are made of muscle fibers Fibers are bundled into fascicles Fascicle organization classifies muscle type

Parallel Muscle Most skeletal muscles Many have a central body in the middle Ex: Biceps brachii

Convergent Muscle Broad muscles that attach at a common attachment site Ex: Pectoralis muscles

Pennate Muscle Fascicles form an angle with the tendon Ex: Extensor digitorum Rectus femoris Deltoid

Circular Muscle Sphinchters Concentrically arranged around an opening Ex: Orbicularis oris

Muscle Terminology Muscles can be identified by their origin, insertion, and action Origin Where the fixed end of a muscle attaches to bone, cartilage, or connective tissue Insertion Where the movable end attaches to another structure Action Movement from muscle contraction

The Axial Muscles On the axial skeleton Functions: 60% of muscles Position head and spinal column Move the rib cage Make breathing possible 60% of muscles

The Appendicular Muscles Move the skeleton 40% of muscles

Aging and the Muscular System Skeletal muscle fibers: Become smaller Lose elasticity Lose tolerance for exercise Higher recovery time from injury

Cardiac Muscle Contracts ~70 times/minute Pumps ~5 liters blood/minute Intercalated disc connects muscle fibers; allows transport of ions between cells Nuclei

Smooth Muscle Found in the walls of all the hollow organs of the body (except the heart) Regulates flow of blood through the arteries Moves food through GI tract Expels urine Pushes babies out Regulates flow of air through the lungs Involuntary

Skeletal Muscle Muscles attached to the skeleton Voluntary Striated