Lecture 6 - Neuromuscular Aspects of Movement I Flashcards
what is musculature?
- the muscles over the skeleton that provide the means to move it
- each muscle produces motion when it creates tension (shortens)
- how muscles look determines how the bones will move
what is the structure of superficial muscles compared to deep muscles?
- superficial are bigger but less powerful (less torque)
- deep are smaller but have more specific actions
how do the shape and wrapping of muscles affect function?
- muscle fibres run along the striations, and the nuclei of the muscle fibres handle actions locally
- the direction of striations tells you the direction of pull of the muscle
- redirect muscle pull between the origin and insertion
what is the ‘origin’?
- proximal attachment of the muscle
what is the ‘insertion’?
- distal attachment of the muscle
what is aponeurosis?
- wide bands of connective tissue that connect muscle to bone
what are the layers of muscle?
- muscle (covered by epimysium)
- fasicles (covered by perimysium)
- muscle fibres (covered by endomysium)
- myofibrils
what is a sarcomere?
- the smallest contractile unit of muscle
- hundreds are connected to form a long chain (in parallel) to form a myofibril (several of which then form muscle fibers)
how does the number of myofibrils affect the muscle?
- lower number of myofibrils = more accurate actions, but lower power/force (like eyes)
- higher number of myofibrils = less accurate actions, but more power/force (like the glutes)
what is the structure of a sarcomere?
- actin = thin filament
- myosin = thick filament
- z disc = where one sarcomere ends and the next starts
- a band = myosin
- i band = contains z line and half actin
- sarcomeres shorten when stimulated by an ATP
- organized into hexagons (each myosin is surrounded by 6 actin)
how does rigor occur in the body?
- when the body no longer has ATP, muscles stay contracted
- smaller muscles go into rigor first, large muscles last
what is the length-tension relationship?
- tension created by a sarcomere related to its length
what is the ideal length-tension relationship? what is not ideal and why?
- ideal = 2 (2.20-2.25 u)
- 1 (>3.65 u) = no connections so slower contraction and movement (0% tension)
- 5 (<1.05 u) = actions will bump into each other and interfere/block with cross bridges (slower contraction)
what is the pennation angle? how does it affect muscle function?
- the angle between muscle fibres and the line of pull
- smaller angle = more direct pull (but less force and greater excursion) and vice versa
what are the different pennation arrangements?
- longitudinal = fusiform muscle (pulls vertically)
- unipennate = more fibres in parallel, aponeurosis
- bipennate = two directions of pull
- multipennate = weakness in the body, a muscle that is trying to do many things (has multiple directions of pull, slower contraction, weaker pull)
what are the 4 important characteristics of a muscle?
- flexibility - ROM at the joint
- strength - maximum force that can be produced
- power - speed the muscle produces force
- endurance - time te muscle can produce force
what are muscle groups?
- grouped together by what they do biomechanically at the joint (ex: knee extensors)
what are one-joint muscles/uniarticulate muscles?
- muscles that only cross one joint
- they only affect one joint when contracted
what are multiarticulate or multi-joint muscles?
- muscles that cross two or more joints
- affect several joints simultaneously when they contract
what is active insufficiency?
- muscle can’t shorten enough
- for example: knee is fully flexed and hip is fully extended, insufficiency in hamstrings
what is passive insufficiency?
- muscle can’t lengthen enough
- for example: hip is fully flexed, knee is fully extended, insufficiency in the hamstrings
what is co-contraction?
- when both the agonists and antagonists are active, to stabilize a joint
- agonists start movement
- antagonists slow things down
- co-contract to stabilize and for fine control (isometric movement or putting something heavy down)
what is concentric contraction?
- when the muscle activated shortens
what is eccentric contraction?
- when the muscle activated lengthens
- produces moe force using the same or less energy, the best way to gain muscles quicker
what is isometric contraction?
- when the muscle activated stays the same length
what 3 factors influence tension?
- amount of activation
- length of the muscle
- speed of the muscle
