Movement Science: Lecture 6 - the shoulder complex Flashcards
what is the shoulder complex made up of
clavicle , scap , humerus
what are the 4 joints that make up the shoulder complex
GH joint
SC joint
AC joint
ST joint
how much motion of the shoulder complex is at the GH joint and ST joint
2/3 at GH
1/3 at ST
what is the normal ROM of the shoulder
180°
_____ stabilization is an active force that provides greater control than passive
dynamic
what occurs ipsilaterally with shoulder elevation
upper thoracic rotation
what is the only structural attachment between axial skeleton and the shoulder
sternoclavicular joint
What type of joint is the SC joint?
saddle
what are the 3 degrees of freedom at the SC joint
elevation/depressoin
protraction /retraction
anterior/ posterior rotation
elevation/ depression (of the SC) happen between the ___ and ___
disc and clavicle
protraction/ retraction(of the SC) happen between the ___ and ___
disc and manubrium
anterior/posterior rotation (of the SC) happen between the ___ and ___
clavicle and 1st rub costocartilage
what is the difference between the superior and inferior joint of the SC joint
superior: medial clavicle and disc
inferior: medial clavicle with manubrium and 1st costal cartilage
the disc increases _____________ and absorbs ____________.
congruence
forces
describe the convexity of the clavicle
The clavicle is convex in the superior-inferior direction
describe the concavity of the clavicle
The clavicle is concave in the anterior-posterior direction
describe the convexity of the manubrium
The manubrium is convex in the anterior-posterior direction, matching the concavity of the clavicle.
describe the concavity of the manubrium
The manubrium is concave in the superior-inferior direction, receiving the convex surface of the clavicle.
The SC joint creates 2 seperate cavities and acts as a ___ point during motion
pivot
during elevation / depression (at the SC joint) the clavicle ___ and ___ on the disc
rolls and glides
during protraction/retraction (of the SC joint) the sc ___ and ___ roll and slide on the ___
disc and clavicle
manubrium
which ligaments of the SC ligaments both limit A/P translation : posterior is primary
anterior and posterior SC ligament
the costoclavicular ligament limit ___ of the ___ clavicle
elevation
lateral
the anterior costoclavicular lig fibers run ___ and the posterior fibers run ____
laterally
medially
which ligament of the SC ligaments resist excessive depression of clavicle : and superior gliding of the clavicle on manubrium
interclavicular ligament
why is it important that the anterior and posterior SC ligaments primarily prevent posterior translation of the clavicle?
it is critical in protecting the subclavian artery/vein and brachial plexus that run through the thoracic outlet
during elevation of the SC joint the ___ end of the clavicle moves upward
lateral
upward
during SC elevation the medial end rolls ___ and slides ____ on the sternun
superiorly
inferiorly
- clavicle is convex, manubrium is concave
during depression of the SC joint the lateral end of the clavicle moves___
downwards
during depression of the SC joint the medial end of the clavicle does what
rolls inferiorly and slides superiorly
- clavicle is convex, manubrium is concave
during SC protraction the lateral clavicle moves ___ in the ___ plane
anteriorly
transverse
during protraction of the SC joint the medial clavicel does what on the sternum
rolls and slides anteriorly
- clavicle is concave, manubrium is convex
during retraction of the SC joint the lateral clavicle moves ___
posteriorly
during retraction of the SC joint the medial clavicle does what
rolls and slides posteriorly
- clavicle is concave, manubrium is convex
what joint structure attaches the scapula to lateral clavicle
acromioclavicular joint
the AC joint is a ____ synovial joint with ___- DOF
plane
3
the AC joint allows the scapula to rotate during arm movement which ___ UE motion
increases
what are the possible different orientations of the AC joint?
vertical
medially angled
laterally angled
which ac joint orientation is more vulnerable to shear forces?
vertical orientation
is the AC capsule strong or weak
weak
is the superior or inferior AC ligament stronger
superior
what muscles reinforce the superior AC ligament
deltoid and traps (dynamic stabilizers)
which ligament of the AC joint firmly unites clavicle and scapula
coracoclavicular lig
what 2 other ligaments make up the coracoclavicular lig of the AC joint
conoid and trapezoid lig
what does the conoid lig resist
inferior forces
what does the trapezoid lig resist
posterior translation
there is a coupled ____ clavicle rotation and scapula ____ rotation during arm elevation
posterior
upward
internal and external rotation(20-35°) of the AC joint occurs around the ___ axis
vertical –> maintains contact of scapula with curvature of thorax as clavicle protracts/retracts
anterior and posterior tilting (20-40°) of the AC joint occurs around the ___ axis
oblique coronal –> maintains scapula with vertical curvature
upward (30°) and downward (17°) rotation of the AC joint occurs around the ___ axis
oblique AP –> tilts glenoid fossa up/down
is the AC joint stable ?
not very stable
is the AC joint susceptible to trauma and degenerative changes
yes
what is the most common trauma for the AC joint
contact sport or falls on shoulder with arm adducted
what joint is formed by anterior surface of scapula with throax
scapulothoracic joint
T/F: the ST joint is a true joint
false
the scapula rests 2” from midline between ribs ___-___
2-7
what is the resting position of the scapula
internally rotated
tilted anteriorly
upwardly rotated
how many degrees of ST joint is required to upwardly rotate during arm elevation
60
if you have excessive internal rotation of the ST joint what is that called
scapular winging
what happens at the scapula during shoulder flexion/abduction
protraction
elevation
upward rotation
what happens at the SC joint during shoulder flexion / abduction
protraction
-clavicle rolls anterior , slides anterior on manubrium
posterior rotation w/ elevation
- inferior slide , superior roll at the disc
what happens at the AC joint during shoulder flexion / abduction
upward rotation
- scap/ acromion in relation to clavicle
what happens at the scapular during shoulder lowering / adduction
retraction
depression
downward rotation
What happens at the SC joint during shoulder lowering / adduction?
retraction
- clavicle rolls posterior , glides posterior on manubrium
depression
anterior rotation (to neutral) with depression
-superior slide and inferior roll at the disc
what happens at the AC joint during shoulder lowering/ adduction
downward rotation (scapula/ acromion in relation with clavicle)
what provides stability for the ST joint
structures of the AC and SC joint
ST joint is a premier example of a ____ stabilizer
dynamic
what kind of joint is the glenohumeral joint
ball and socket synovial joint
how many DOF does the GH joint have
3 rotary and 3 translatory
is the humeral head or glenoid fossa bigger
humeral head
which motions of the scapula will influence the GH
any motion
the proximal surface of the GH is shallow ___
concavity
the proximal surface of the GH can be ____ or ____
retroverted or anteverted
the proximal surface of the GH is the ___ ___ of scpaula
glenoid fossa
the distal surface of the GH joint is what
the humeral head
what is the angle of inclincation of the distal surface of the GH
130-150°
what is the angle of torsion of the distal surface of the GH joint
30°
ossification centers
what does the glenoid labrum enhance
fossa concavity
the glenoid labrum serves as an attachment site for GH ____ and tendon of what muscle
ligaments
long head of biceps
what functions to resist humeral head translation , protect bondy edges of fossa, minimize GH joint friction and dissipate joint contact forces
glenoid labrum
the capsule of the GH tightens with ____ and ____
abduction and lateral rotation
how much distraction is available at the GH capsules during loose packed position
> 2.5 cm
the Gh capsule is vulnerable to ____ dislocations
anterior
the superior GH lig resits ___ and ___ translations of humeral head at 0° of abduction
ant and inferior
which GH ligaments prevents any translation of humeral head from 0-60° of abduction
middle Gh lig
the inferior GH ligaments complex is made of of how many components
3 (anterior , posterior and axillary pouch)
what does the anterior component of the inferior Gh lig complex prevent
prevents ant/inf translation (abd/ER)
what does the posterior component of the inferior Gh lig complex prevent
prevents post/inf translation (abd / IR)
what does the axillary pouch component of the inferior Gh lig complex prevent
prevents inf translation (abd)
what forms the tunnel for the long head of the biceps to pass thru
coracohumeral lig
how many bands does the coracohumeral lig have
2
which band of the coracohumeral ligeamnt is at the base of the coracoid to edge of supraspinatus tendon and greater tubercle
first band
which band of the coracohumeral ligeamnt is at the base of the coracoid into subscapularis and less tubercle
second band
what forms the vault over the humeral head
coracoid , acromion , and coracoacromnial lig
what contains subacromial bursa, rotator cuff tendons , and tednon of long head of biceps
subacromial space
the coracoacromial arch protects subacromial structures and prevents ___ dislocation of the ___
superior
humerus
the coracoacrominal arch can be an area of impingement with ___ and a narrowed joint space
supraspinatus
how many degrees of flexion and extension does the GH joint have and around what axis
flexion - 120
extension -50
coronal axis
what are the arthrokinematics of GH shoulder flexion versus extension?
flexion: humeral head spins posteriorly
extension: humeral head spins anteriorly
medial and laterla rotation of the GH joint is around what axis
long
what are the arthrokinematics of GH shoulder internal rotation versus external rotation:?
internal: humeral head rolls anteriorly, slides posteriorly
external: humeral head rolls posteriorly, slides anteriorly
abduction of the Gh joint is limited when in neutral or medial rotation by what
greater tub
how mnay degreees of abduction and adduction is at the GH joint and around what axis
90-120
AP axis
what are the arthrokinematics of GH shoulder abduction versus adduction?
abduction: humeral head rolls superiorly, slides inferiorly
adduction: humeral head rolls inferiorly, slides superiorly
what is required for full shoulder abduction?
external rotation (thumbs back)
during elevation of the GH the humeral head slides ___ and rolls ___
inferiorly
superior
a tight GH capsule can causes the shifting of the humeral head during motion or limit motion AKA ___
inferior slide
where does gravity pull the arm
inferiorly
if the arm is loaded what contracts
supraspinatus
when the arm is loaded there is an ____ inferior subluxation with ___- rotator cuff function
increase
decrease
during dynamic stabilization of the GH joint what muscle is the prime movers for abduction and flexion
deltoids
force vectors of the middle delt are larger ____ rather then ____
parallel
perpendicular
what muscle does the deltoid need synergisitc help from to produce desired rotation of humeral head
rotator cuff
the .I.T.S perpendicular force component causes some ___ of the humerus but also compresses head into _____ fossa
rotation
glenoid
the parallel force component (Fx) of the I.T.S muscles offsets superior translatory force from deltoid by pulling the humeral head ____
inferiorly
what muscles help with lateral rotation to clear the greater tubercle for the GH joint
infraspinatus and teres minor
which muscle has a large rotary component with large moment arm for adbuction of the GH joint
supraspinatus
what is the significance of the large moment arm of the supraspinatus?
1st few degrees of shoulder abduction comes from supraspinatus
(can be a prime mover!)
what ligament runs from the greater and lesser tubercles
transverse humeral ligament
the long head of the biceps can contribute to both ____ and ____ of the shoudler
flexion and abduction
what muscles helos reinforce the GH joint , centering the head and reducing vertical and anterior shear
LHoB
the LHoB may also tighten what
the labrum
overal the dynamic stabilization at any point of ROM of the GH joint is infulenced by
1. force generated by ___ ____
2. force of ____
3. force created by ______ _____
4.articular surface geometry
5. _____ capsuloligamentous forces
6. joint ____ forces
primary movers
gravity
muscular stabilizer
passive
reaction
all forces of the GH compress the humeral head into the ___ ____
glenoid fossa
greatest shear forces of the GH joint occur between how many degrees
30-60° of elevation
which rotator cuff tendon is most vulnerable
supraspinatus
what kind of tears of common in people over 60
RCT
if someone has a rotator cuff tear then they will have pain between what degrees
60-120° (painful arch)
what motion of the shoulder distributes motion between 4 joints , permitting more ROM with more stability
scapulohumeral motion
the scapulohumeral motion maintains _____ ____ in optimal position for humeral head for better joint ____ and decreased ___
glenoid fossa
congruency
shear
the scapulohumeral motion maintains good length tension of humeral muscles preventing ____ insufficiency as the scapula rotates up
active
the scaplohumeral rhythm has first ___ of aduction or___ of flexion
30°
60°
in the initial phase of scapulohumeral rhythm does the Gh or ST move more
GH mostly
during the motion of ST moving 60° what happens at the SC and AC joint
clavicualr elevation at SC
posterior clavicular rotation at AC
the motion during ST motion of 60° causes clavicular elevation at the SC , which muscles upwardly rotate the scapula
trapz and SA
the motion during ST motion of 60° causes clavicular elevation at the SC , which ligament becomes taut
costoclavicular
the motion during ST motion of 60° causes posterior clavicular rotation at AC ,, what happens at the lateral end of the clavicle
it rolls up
the motion during ST motion of 60° causes posterior clavicular rotation at AC ,, which ligaments become taut and what does it prevent
coracoclavicualr (conoid and trapezoid) and costoclavicular lig become taut and prevents more elevation
for ST upward rotation to occur there has to be a force couple of what muscles
upper trap , lower trap and SA
what muscles are a force couple for ST upward rotation and also produce and control tipping and rotation during elevation
traps and SA
deltoid-rotator cuff force couple
SITS muscles counteract the upward force of deltoids to prevent superior humeral head dislocation
upper traps and serratus anterior force couple
SA and traps upwardly rotate the scapula to thorax –> prevents impingement
Anterior/Posterior rotator cuff muscle force couple
subscapularis and infraspinatus/teres minor forces oppose each other –> prevents excessive anterior/posterior translation of the humeral head
