Exam #3 (Lecture 10; Kinematic Principles) Flashcards

1
Q

what is scapulohumeral rhythm

A

natural rhythm between GH abduction and scapulothoracic upward rotation
after 30 degrees abd this rhythm is consistent

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2
Q

what is the ratio for scapulohumeral rhythm?

A

2:1
every 3 degrees abd: 2 deg at GH joint, 1 deg at ST upward rotation

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3
Q

a full arc 180º is from ____ GH ______ ST

A

120º GH
60º ST

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4
Q

During 60º of ABD of the scapula what is happening at the SC joint? AC joint?
-SC elevates how many degrees?

A

simultaneous elevation of the clavicle at the SC joint combined with upward rotation of the scapula at the AC joint.
*SC elevates 30 degrees during the 180

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5
Q

at anatomical position clavicle sits _____ degrees ________ to frontal plane.
during abd it retracts another _______ deg

A

20 degrees posterior
15-20 degrees

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6
Q

when full abduction occurs, which way does the scapula move?

A

scapula tilts posteriorly 20 deg and slightly rotates outward
AC and SC rotate

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7
Q

at rest, how does the scapula sit?

A

anterior tilted 10 deg
internally rotated 30-40 deg

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8
Q

the posterior tilting and external rotation helps the scapula by: (3)

A

keeping scapula flush with the thorax
orients the fossa
moves the coracoacromial arch away from advancing humeral head

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9
Q

clavicle rotates _____ along its own axis
_______ degrees during full abduction

A

posteriorly
20-35 deg

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10
Q

when does the clavicle move the most?

A

in middle and late ranges with abduction

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11
Q

Those who have subacromial impingement, will show reduced _______

A

Posterior rotation of clavicle

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12
Q

what does the humerus naturally do during abduction? what does this allow?

A

externally rotates
allows greater tubercle on the humerus to pass posterior to the acromion

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13
Q

majority of external rotation of humerus during abduction happens around _______ degrees
but majority occurs BEFORE ______ degrees

A

25-50
70-80

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