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 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 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 Shape
Biceps Brachii Action Trapezius Number of muscle attachments Transversus abdominus Adductor Longus Points of attachment to skeleton Bone The Relationship Relationshi
p Bone: lever Muscle Joint: Fulcrum (a fixed point around which a lever moves) Muscle: force to move the lever Joint Origin & Insertion Origin of a Muscle Insertion of a Muscle Attaches to bone that remains stationary during contraction
Attaches to a bone that moves during contraction Gives the muscle something to move against A muscles insertion will move towards its origin Antagonist Muscle Pairs Yin and Yang Muscle opposites
A balance between opposing forces Antagonist vs. Agonist Agonist Antagonist 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? Helpers Synergists Fixators Stabilizes a joint where the movement is occurring Stabilizes the origin of the agonist muscle This will also help the agonist do its
job 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 Contraction with no change in length Isotonic
Contraction with muscle shortening and lengthening Concentric Contraction Ex: wall sit, plank, etc. 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
