Muscles 2 - BIO10004 Week 4.3 PDF

Muscles 2 Dr Greg Davis Martini Chapter 11 Copyright notice  Learning objectives and reading At the end of this lecture you should be able to: 1. Describe the arrangement of fascicles in the various types of muscles and explain the resulting functional differe...

Muscles 2 Dr Greg Davis Martini Chapter 11 Copyright notice  Learning objectives and reading At the end of this lecture you should be able to: 1. Describe the arrangement of fascicles in the various types of muscles and explain the resulting functional differences 2. Describe the classes of levers, and explain how they make muscles more efficient 3. Predict the actions of a muscle on the basis of its origin and insertion, and explain how muscle interact to produce of oppose movement 4. Explain how the name of a muscle can help identify its location, appearance or function 5. Identify age-related changes to the muscular system Reading guide (textbook): Sections: 11-1, 11-2, 11-3, 11-4, 11-7 Figures: 11-1, 11-2, 11-4 Questions: 4, 14, (20, 27)  Muscle systems (Ch 11) Muscles fibres form bundles called fascicles – Muscles = Fascicles + conn tissue + nerves + blood vessels Fascicles arrangement provides muscle classification – Parallel – Convergent – Pennate – Circular Muscle types  Muscle types Parallel – Fibres parallel to long axis of muscle – Large proportion of muscles are this type – Most have tendons at each end – Contraction shortens and fattens the muscle – Example biceps brachii (in the upper arm) Convergent – Fan shaped, narrow attaching to tendon at one end – Broad attachment at other end – Example pectoralis muscle of chest Muscle types  Muscle types Pennate – Form a common angle with tendon – Direction of pull of fibres is not parallel to muscle body – Generate less movement, but more force – Example rectis femoris muscle of knee is bipennate Circular – Arranged circumferentially – Also known as a sphincter muscle – Contraction closes the opening – Example obicularis oris (mouth)  Lever systems Add value to muscle function 1st class – Provide additional force or movement Classified in standard way – Load (what we move) – Fulcrum (pivot point) 2nd class – Applied force (muscle pull) Majority 3rd class in body 3rd class  Levers 1st class Fulcrum is in centre Seesaw Head on neck example  Levers 2nd class Fulcrum (pivot) is at end Load is in middle Wheelbarrow Foot/ankle is an example  Levers 3rd class Fulcrum is at one end Load is at opposite end Tweezers Elbow joint is one of many examples  Origin and insertion Two ends of the muscle – Origin usually proximal and fixed end for muscle action – Insertion usually distal and moveable end for action – For the gastrocnemius muscle below the insertion (calcaneus) moves while the origin (femur) stays fixed origin insertion  Muscle actions/labels Agonist – Prime mover major involvement in movement Antagonist – Opposes prime mover produces opposite action – Roles reverse for opposite movement Synergist – Assists prime mover in action Fixator – Helps stabilise a joint or motion  Muscle names See Table 11-1 – Location in the body abdominus – Origin and insertion First part (origin) /second part (insertion), e.g. genioglossus: chin to cheek) – Fascicle organisation Rectus, oblique, transverse – Position Externus (external), profundus (deep) – Structural characteristics Trapezius, number of heads (biceps) – Action Flexor, extensor, pronator, abductor etc  Ageing and muscles Skeletal muscles – become smaller – Become less elastic – Exercise tolerance decreases – Recovery from injury decreases Regular exercise mitigates and slows some of these  Effects of exercise Muscular system interacts with many others Cardiovascular – Blood vessels dilate – Heart rate increase – Heat for the body returned via blood Respiratory – Rate and depth increases to supply more oxygen Integumentary – Superficial blood vessels dilate more blood to skin – Sweat glands become active to manage heat and temp  Summary Muscle types – Parallel, convergent, pennate, circular Lever systems – Class 1, 2, 3 Origins and insertions Names of muscles Overview of muscular system Ageing and muscles Effects of exercise