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48 Cards in this Set

  • Front
  • Back
What are the 3 joints of the elbow?
HU
HR
RU
1 degree of freedom
What type of joint is the elbow?
modified loose hinge joint
stability at the elbow comes from?
bone configuration
Valgus means?
turned outward like abduction
Varus means?
turned inward like adduction
HU joint loose and close packed positions?
loose = flexed ~70 degrees
close = fully extended
HR joint loose and close packed positions?
loose = fully extended
close = flexed 90 degrees
Stretch of what ligament resists valgus motion?
MCL
Stretch of what ligament resists varus motion?
LCL
distal RU joint is an articulation btw?
concave radius
convex ulna
what are RU ligaments that can limit motion?
dorsal and ventral RU ligaments
what type of joint is the RU?
pivot joint = 1 degree of freedom
what is the primary motion of the RU?
supination and pronation
what are the loose and close packed positions of the RU?
loose = ~70 flexion, ~35 supination

close = full extension, ~5 supination
Motion of the radial joint surface in Humeroradial Flexion
Anterior roll, Anterior slide
Motion of distal radial joint surface in Distal Radioulnar Pronation (radius on ulna)
Anterior roll, Anterior slide
Motion of rim of radial head in Proximal Radioulnar Supination
Posterior roll, Anterior slide
Motion of ulnar joint surface in Humeroulnar Extension
Posterior roll, Posterior slide
Motion of ulnar joint surface in Humeroulnar Flexion
Anterior roll, Anterior slide
Motion of rim of radial head in Proximal Radioulnar Pronation (radius on ulna)
Posterior roll, Anterior slide
Motion of rim of radial head in Proximal Radioulnar Pronation (radius on ulna)
Anterior roll, Posterior slide
Motion of distal radial joint surface in Distal Radioulnar Supination
Posterior roll, Posterior slide
what limits pronation?
dorsal RU ligament
what limits supination?
ventral RU ligament
Muscles that attach distally on the ulna do what?
flex or extend elbow with no ability to pronate or supinate
muscles that attach distally on the radius may?
flex or extend elbow and pronate or supinate forearm
what are the elbow flexors?
brachialis 2
biceps 3
brachioradialis 2
which muscle is a better elbow flexor?
Biceps brachii
why would brachioradialis be a good stabilizing muscle?
b/c line of action is close to stabilizing component and closer to going through axis of rotation which produces 0= T
at what angle of flexion can the elbow flexors produce the most torque and why?
90-100 degrees flexion b/c of mechanical and physiological factors
what shoulder position stretches the biceps brachii?
shoulder extention
what shoulder position shortens the biceps brachii?
shoulder flexion
what forearm position stretches the biceps brachii?
pronation
what forearm position shortens the biceps brachii?
supination
what muscles are the elbow extensors?
1. triceps brachii long - 2
2. triceps brachii medial and lateral - 1
3. anconeus - 1
what direction is torque produced during tricep contraction?
clockwise
what compensates a small moment arm?
large CSA
what results from elbow extension?
1. tangential component of the force increases
2. triceps move away from optimal length
what shoulder position stretches the triceps?
shoulder flexion
what shoulder position shortens the triceps?
shoulder extension
which muscles are the pronators?
1. pronator teres
2. pronator quadratus
what do the pronators do?
pull on radius, causing it to turn over ulna
pronators are stronger when?
forearm is supinated
what muscles are the supinators?
1. supinator - 2
2. biceps brachii - 3
what do the supinators do?
pull shaft and distal end of radius over ulna
when are the supinators the strongest?
when forearm is pronated
what accompanies pronation due to pronator teres?
triceps activation to prevent elbow flexion
what angle is the biceps brachii a better supinator?
when elbow is flexed at 90 degrees