Exam #3 (Lecture 10; Kinematic Principles) Flashcards
what is scapulohumeral rhythm
natural rhythm between GH abduction and scapulothoracic upward rotation
after 30 degrees abd this rhythm is consistent
what is the ratio for scapulohumeral rhythm?
2:1
every 3 degrees abd: 2 deg at GH joint, 1 deg at ST upward rotation
a full arc 180º is from ____ GH ______ ST
120º GH
60º ST
During 60º of ABD of the scapula what is happening at the SC joint? AC joint?
-SC elevates how many degrees?
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
at anatomical position clavicle sits _____ degrees ________ to frontal plane.
during abd it retracts another _______ deg
20 degrees posterior
15-20 degrees
when full abduction occurs, which way does the scapula move?
scapula tilts posteriorly 20 deg and slightly rotates outward
AC and SC rotate
at rest, how does the scapula sit?
anterior tilted 10 deg
internally rotated 30-40 deg
the posterior tilting and external rotation helps the scapula by: (3)
keeping scapula flush with the thorax
orients the fossa
moves the coracoacromial arch away from advancing humeral head
clavicle rotates _____ along its own axis
_______ degrees during full abduction
posteriorly
20-35 deg
when does the clavicle move the most?
in middle and late ranges with abduction
Those who have subacromial impingement, will show reduced _______
Posterior rotation of clavicle
what does the humerus naturally do during abduction? what does this allow?
externally rotates
allows greater tubercle on the humerus to pass posterior to the acromion
majority of external rotation of humerus during abduction happens around _______ degrees
but majority occurs BEFORE ______ degrees
25-50
70-80
