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34 Cards in this Set
- Front
- Back
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Movement of muscles and bones
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physical laws governing posture
Evolutionary history - aboreal to bipedal clinically important - example, bariatic surgery, people > 400 lbs (stomach stapling) only way a small nurse can move such a large person |
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relationship between muscles, tendons and bones
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muscles attach through tendons
origin - stationary bone insertion - end, greatest movement belly |
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muscle actions
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agonist - with motion
antagonist - against motion synergists - work together for motion primer mover - major mover fixators - stabilize articulations |
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nomenclature of muscle
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location - gluteus, pectoral, brachial (arm)
size - maximus, minimus, longus, brevis shape - deltoid (triangle), quadratus (rectangle), teres (round) orientation - rectus (straight), oblique (angle) ; relative to bone origin and insertion - sternocleidomastoid (originates on the sternum and clavicle and inserts into the temporal bone mastoid process origin number and function (masseter-chew) |
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skeletal muscle number
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~639 individual muscles
- gastrocnemius (origin- femur, insertion - calcaneus, knee flexion) |
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Fiber organization
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microscopic and macroscopic levels
axis of force generation - axis of applied tension (parallel, pennate(at an angle to bone), convergent, circular) relative to the bone |
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parallel fibers
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parallel to axis of force generation
develop tension rapidly cannot develop as much force e.g. sartorius |
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pennate
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angle to axis of force generation (up to 30 degrees)
unipenate - one side of bone bipennate - both sides, rectus femoris... multipennate - many angles, deltoid, arm abduction Slower to develop tension more muscle fiber in the same volume, stronger |
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Convergent
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many muscle fibers converge on a single point...
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Circular
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sphincter muscles
arranged in a circle change diameter of opening contraction - decreases opening relaxation - increases opening urinary bladder, digestive tract |
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extrinsic
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properties vary with absolute muscle size
cross-sectional area or mass (density of sarcomeres) affected by fiber arrangement |
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intrinsic
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propertiest independent of muscle size
fiber length, fiber length/muscle length does not change at all from birth |
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differences
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(extrinsic)muscle tension + cross sectional area
how strong (intrinsic)muscle velocity + muscle fiber length how fast they can contract |
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example
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same fiber length, same pennate angle, different cross sectional area
muscle with larger CSA produces more tension both muscles contract at the same speed |
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Why does a longer muscle contract faster than a shorter muscle?
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because the ends approach each other at a faster rate (lots of people taking half step inward)
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Intrinsic properties
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same cross sectional area, same pennate angle, different length
- longer muscle contracts faster - longer muscle generates tension over a longer length - greatere number of sarcomeres... |
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What are muscle biomechanics
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mechanics applied to muscle
application of engineering principles to muscle action realization that applied loads and deformations can affect soft tissues (elastic, bend and twist) |
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bones
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anisotropic and transversely isotropic
stronger along long axis than across middle (like can of soda) same strength no matter how they are rotated (callogen gives strenth in rotation) |
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soft tissues roles
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tendons, ligaments and cartilage
collagen bears the most strain (strongest) elastin within skin, vasculature, connective tissue tendons - stretch, great tensile strength ligaments - stiffer, same tensile strength cartilage - cushion (wet noodle) - compression |
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relationship to muscle
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biomechanic properties of bones and soft tissues affect ...
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different biomechanic studies
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kinematics - study of motion with cameras
dynamics - study of force that causes motion kinetics - both |
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Newton's Laws of Motion
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1rst law - an object in motion remains in motion unless an external force is applied to it
2nd law - force equals mass times acceleration 3rd law - for every action there is an equal and opposite reaction |
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Elasticity and compression
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body is not completely rigid
elastic recoil (rubber band) elastic recoil you are shorter standing up |
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Compressive forces
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bone is 4x stronger than concrete
... |
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muscle levers
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first class lever - fulcrum in middle of two forces
2nd class lever - fulcrum at end 3rd class lever - elbow |
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class 1 lever
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between weight and load, seesaw
trades speed for strength reveres direction very uncommon |
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class 2 lever
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oad is between force and fulcrum
great amount of weight lifted but not for great distance reverses direction, trade speed for strength still uncommon |
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class 3 lever
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force is between the load and fulcrum
hand lifted by biceps trade speed for strength most moveable joints in the body |
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muscle movement
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muscles develop tension to move loads
the force required is decreased by use of levers biomechanical properties of soft tissues biomechanical properties of bones and joints |
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ergonics
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physical - study of physical shapes to minimize muscle pain
cognitive - design of objects to facilitate perception, attention (color, shape of stop signs) organizational - design of large systems |
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physical ergonomics
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arthritis - doorknobs, can openers (lever like instead of round)
carpal tunnel syndrome - keyboard design cell phones |
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clinical relevance
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moving bariatric patients
300 - 1200 lbs special training and techniques everything must support 100 lbs ergonomics used one nurse per 500 lb patient |
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training
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use of training to reduce back injuries
rolling, stable.... |
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pathophysiology
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sprain - ligament overstretch or tear
inflammation pain swelling delayed onset muscle soreness 24 to 72 hrs after use eccentric contractions muscle cell damage - body building |
