Muscles

Muscular System 3 types Visceral (smooth): found inside organs (stomach, intestines, etc.) Cardiac: found in the heart Skeletal: attached to our skeleton

Skeletal Muscles: Functions Create voluntary, conscious movement Maintains posture Produces heat Stabilizer of joints

Muscle Anatomy Fascia Epimysium Perimysium Fascicle Bands or sheets of fibrous connective tissue Fascia surrounds organs, muscles, tissues; looks like a very thin spider web Epimysium Surrounds the entire muscle “epi” means upon or above Perimysium Fascia surrounding each fascicle “peri” means around Fascicle Bundle of muscle fibers

Muscle Anatomy Myofibril Myofilaments Sarcomere Thinner fibers within each muscle fiber Myofilaments Proteins within each myofibril: actin/myosin Actin = thin filaments Myosin = thick filaments Sarcomere Groups of myosin and actin Fundamental subunits of muscle contractions video

Sliding Filament Theory Actin & myosin slide in and out between each other to form muscle contractions Z-band: lateral ends of sarcomere

Naming Muscles: Characteristics in Muscle Names Size Gluteus Maximus/Medius/Minimus Location/Position Direction of fibers Transversus abdominus Shape Trapezius Number of muscle attachments Biceps Brachii Action Adductor Longus Points of attachment to skeleton

The Relationship Bone: lever Joint Muscle The Relationship Bone: lever Joint: Fulcrum (a fixed point around which a lever moves) Muscle: force to move the lever

Origin & Insertion Origin of a Muscle Insertion of a Muscle Attaches to bone that remains stationary during contraction Gives the muscle something to move against Attaches to a bone that moves during contraction A muscles insertion will move towards its origin

Antagonist Muscle Pairs Yin and Yang Muscle opposites A balance between opposing forces

Antagonist vs. Agonist Elbow flexion: Agonist? Antagonist? Agonist Prime mover Mainly responsible for contracting and carrying out a body movement Allows the movement to happen by relaxing Performs a movement exactly opposite to that done by the agonist muscle Elbow flexion: Agonist? Antagonist?

Helpers Synergists Fixators Stabilizes a joint where the movement is occurring This will also help the agonist do it’s job Stabilizes the origin of the agonist muscle Stabilizes the joint that the movement moves over Bicep Curl: rotator cuff muscles are fixators Mostly found in shoulder & hips

Principle of Opposing Muscle Action “Whenever a particular agonist and its synergist are excited and contract, the antagonist is inhibited and relaxed.” This occurs all because of the nervous system Can you contract an agonist and antagonist at the same time? What would happen? Body-lock or rigid

Muscle Contractions Isometric Isotonic Contraction with no change in length Ex: wall sit, plank, etc. Contraction with muscle shortening and lengthening Concentric Contraction Positive contraction; muscle shortens while tension develops to overcome or move some resistance Eccentric Contraction Negative contraction; the resistance is greater than the muscular force being produced, and the muscle lengthens while producing tension