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48 Cards in this Set
- Front
- Back
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What are the 3 joints of the elbow?
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HU
HR RU 1 degree of freedom |
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What type of joint is the elbow?
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modified loose hinge joint
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stability at the elbow comes from?
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bone configuration
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Valgus means?
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turned outward like abduction
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Varus means?
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turned inward like adduction
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HU joint loose and close packed positions?
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loose = flexed ~70 degrees
close = fully extended |
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HR joint loose and close packed positions?
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loose = fully extended
close = flexed 90 degrees |
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Stretch of what ligament resists valgus motion?
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MCL
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Stretch of what ligament resists varus motion?
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LCL
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distal RU joint is an articulation btw?
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concave radius
convex ulna |
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what are RU ligaments that can limit motion?
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dorsal and ventral RU ligaments
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what type of joint is the RU?
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pivot joint = 1 degree of freedom
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what is the primary motion of the RU?
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supination and pronation
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what are the loose and close packed positions of the RU?
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loose = ~70 flexion, ~35 supination
close = full extension, ~5 supination |
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Motion of the radial joint surface in Humeroradial Flexion
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Anterior roll, Anterior slide
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Motion of distal radial joint surface in Distal Radioulnar Pronation (radius on ulna)
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Anterior roll, Anterior slide
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Motion of rim of radial head in Proximal Radioulnar Supination
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Posterior roll, Anterior slide
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Motion of ulnar joint surface in Humeroulnar Extension
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Posterior roll, Posterior slide
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Motion of ulnar joint surface in Humeroulnar Flexion
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Anterior roll, Anterior slide
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Motion of rim of radial head in Proximal Radioulnar Pronation (radius on ulna)
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Posterior roll, Anterior slide
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Motion of rim of radial head in Proximal Radioulnar Pronation (radius on ulna)
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Anterior roll, Posterior slide
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Motion of distal radial joint surface in Distal Radioulnar Supination
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Posterior roll, Posterior slide
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what limits pronation?
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dorsal RU ligament
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what limits supination?
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ventral RU ligament
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Muscles that attach distally on the ulna do what?
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flex or extend elbow with no ability to pronate or supinate
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muscles that attach distally on the radius may?
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flex or extend elbow and pronate or supinate forearm
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what are the elbow flexors?
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brachialis 2
biceps 3 brachioradialis 2 |
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which muscle is a better elbow flexor?
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Biceps brachii
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why would brachioradialis be a good stabilizing muscle?
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b/c line of action is close to stabilizing component and closer to going through axis of rotation which produces 0= T
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at what angle of flexion can the elbow flexors produce the most torque and why?
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90-100 degrees flexion b/c of mechanical and physiological factors
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what shoulder position stretches the biceps brachii?
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shoulder extention
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what shoulder position shortens the biceps brachii?
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shoulder flexion
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what forearm position stretches the biceps brachii?
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pronation
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what forearm position shortens the biceps brachii?
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supination
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what muscles are the elbow extensors?
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1. triceps brachii long - 2
2. triceps brachii medial and lateral - 1 3. anconeus - 1 |
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what direction is torque produced during tricep contraction?
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clockwise
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what compensates a small moment arm?
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large CSA
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what results from elbow extension?
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1. tangential component of the force increases
2. triceps move away from optimal length |
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what shoulder position stretches the triceps?
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shoulder flexion
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what shoulder position shortens the triceps?
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shoulder extension
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which muscles are the pronators?
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1. pronator teres
2. pronator quadratus |
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what do the pronators do?
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pull on radius, causing it to turn over ulna
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pronators are stronger when?
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forearm is supinated
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what muscles are the supinators?
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1. supinator - 2
2. biceps brachii - 3 |
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what do the supinators do?
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pull shaft and distal end of radius over ulna
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when are the supinators the strongest?
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when forearm is pronated
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what accompanies pronation due to pronator teres?
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triceps activation to prevent elbow flexion
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what angle is the biceps brachii a better supinator?
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when elbow is flexed at 90 degrees
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