Shoulder Flashcards
which ligament resists elevation and protraction at the AC joint?
conoid ligament
which ligament provides AC joint compression?
trapezoid ligament
which ligament covers the entire AC joint capsule and reinforces its superior aspect?
acromioclavicular ligament
during clavicle elevation, ______ ligaments develop tension that results in ____ rotation of the clavicle and resist upward rotated forces of the scapular
costoclavicular ligaments (trapezoid & conoid)
posterior
what motions do the costoclavicular ligament complex resist?
excessive superior, anterior, and posterior movement of the medial end of the clavicle
what ligament provides restraint to inferior forces on the medial end of the clavicle?
interclavicular ligament
main purpose of the costoclavicular ligament
create fulcrum for 1st rib and clavicle to allow the scapula to fully upwardly rotate due to clavicular elevation
which motion is occurring with an inferior glide of the SC joint?
elevation
convex/concave rule at the SC joint
elevation/depression - vex on cave
horizontal abd/add - cave on vex
spinal level?
superior border of scapula
inferior border of scapula
spine of scapula
superior - T2
inferior - T7
spine - T3
the ST joint is angled _____ deg from the coronal plane
30-45 deg
at rest, the scapula is _______ rotated 10-20 deg and tips ______ 10-20 deg
upwardly
anterior
GHJ flexion, IR, horizontal adduction arthrokinematics
posterior glide**
anterior roll
GHJ extension, ER, & horizontal abduction arthrokinematics
anterior glide**
posterior roll
GHJ abduction arthrokinematics
inferior glide
superior roll
GHJ adduction arthrokinematics
superior glide
inferior roll
which part of the GHJ capsule is the weakest?
anterior
open pack position of GHJ
55 deg abduction
30 deg horizontal adduction
(scaption)
open pack position for AC and SC joints
arm resting at side
closed pack position for GHJ
90 abduction
full ER
closed pack position for AC joint
90 deg abduction
closed pack position for SC joint
full shoulder elevation
capsular pattern of GHJ
ER, abduction (flexion), IR
where should the scapula be positioned during full GH elevation?
midaxillary line
the humerus needs to do what in order to clear the greater tuberosity of the acromion during elevation?
ER 35-45 deg
during the initial ______ of humeral elevation, no scapular movement occurs
20-30 deg
60 deg of ST upward rotation occurs during humeral elevation which includes _____ at the SC joint and ______ at the AC joint
25 deg SC elevation
35 deg AC posterior (upward) rotation
which directions are the force of the deltoid on the humerus?
upward and outward
the superior directed force of the deltoid is counteracted by what?
inferior and medial directed force of infraspinatus
what muscle provides a compressive force at GHJ?
supraspinatus (approximating role)
describe the force couple between the deltoid and the rotator cuff
deltoid is offset by the horizontal force of the rotator cuff as they act in opposite directions on either side of the center of rotation
upper fibers of SA action vs lower
upper - protraction at 90 deg
lower - upward rotation at 120-135 deg
what are the 4 crucial functions in the shoulder?
- maintain glenoid surface for optimal positioning of humerus
- length-tension relationship for deltoid
- prevent RC impingement
- stable scapular base for scapulohumeral muscles
which muscles does posterior tipping of the scapula and can be exercised with a lift off?
posterior trap
which force couple creates inferior dynamic stability and the concavity-compression mechanism?
subscapularis, infraspinatus, and teres minor
(compress humeral head into glenoid fossa)
subscapularis, infraspinatus, and teres minor are most active in ____ range
mid
if you observe a pt that has an anterior glide of the humerus, what is suspected?
dominant posterior cuff (subscap - IR)
ex: supraspinatus tear
the SA works in combination with the ____ & _____ to produce upward rotation of the scapula
upper & lower traps
what is a better position to exercise ERs and upward rotators for stability?
overhead
what should be done before strengthening?
activation
a shoulder shrug is a compensation by the ____ for _____
deltoid for the RC
