Shoulder Complex Flashcards
What are the components of the shoulder complex?
Mobility with dynamic stability •Sternoclavicular joint •Acromioclavicular joint •Glenohumeral joint •Scapulothoracic “joint”
What are the bones which make up the sternoclavicular joint?
Medial clavicle with notch formed by manubrium and 1st costal cartilage
What type of joint is the SC joint?
Saddle joint
How is the SC joint reinforced and stabilized?
Fibrous joint capsule
Posterior portion - restrain ant/post translation of medial clavicle
How is the SC joint reinforced and stabilized?
Anterior/posterior sternoclavicular lig
Restrict anterior and posterior translation of clavicle
How is the SC joint reinforced and stabilized?
Costoclavicular lig
Anterior and posterior bundles
- Limit elevation of lateral clavicle
- Contribute to inferior glide of medial clavicle in elevation
- Shock absorption
How is the SC joint reinforced and stabilized?
Interclavicular lig
Limits excessive depression and superior glide of clavicle
Describe the osteo of the SC joint.
Elevation/depression
Protraction/retraction
anterior/posterior rotation
Describe the arthrokinematics of the SC joint.
Superior/inferior
anterior/posterior
spin
Describe Elevation/Depression at SC joint:
-Disc remains stationary
-Convex on concave movement
Elevation - Superior roll and inferior glide
Depression - Inferior roll and superior glide
Describe Protraction/Retraction at SC joint:
-Disc moves with clavicle
-Concave on convex movement
Protraction - Anterior roll and glide
Retraction - posterior roll and glide
Describe anter/posterior rotation at SC joint:
Posterior rotation - inferior surface moves anteriorly
Anterior rotation - Inferior surface returns to inferior position (minimal motion from neutral)
What is the open pack position and capsular pattern for the SC joint?
Open pack = arm resting at side
Capsular pattern = pain at end range with arm overhead
What are the bones which make up the acromioclavicular joint?
Lateral clavicle
Acromion
What type of joint is the AC joint?
Plane synovial
How is the AC joint reinforced and stabilized?
Joint capsule -
weak, requires reinforcement
How is the AC joint reinforced and stabilized?
Superior acromioclavicular lig
- Reinforced by deltoid and trap
- Resists anterior clavicular/posterior acromion translation
How is the AC joint reinforced and stabilized?
Inferior acromioclavicular lig
Most susceptible to downward dislocation
How is the AC joint reinforced and stabilized?
Coracoclavicular lig
- Trapezoid and conoid lig
- Limit superior clavicular/inferior scapular translation and posterior rotation of clavicle
Describe the osteo of the AC joint.
Internal/external rotation
Ant/post tilting (tipping)
Upward/downward rotation
Describe the arthrokinematics of the AC joint.
Ant/post
sup/inf
medial/lateral
Primary function of AC joint is:
Allow scapula to rotate during arm movement
Why is internal/external rotation at AC joint important?
Maintain contact of scapula on curved thorax during protraction and retraction of clavicle
Why is Anterior/posterior tilting (tipping) at AC joint important?
Maintain contact of scapular on curved thorax during elevation and depression of clavicle
Why is Upward/downward rotation at AC joint important?
-Important for positioning glenoid fossa in optimal position
Upward - scapula swing up and out (abduction or flex of shoulder)
Downward - scapula back to anatomical position (adduction or extension of shoulder)
What is the open pack position and capsular pattern for the AC joint?
Open pack = arm by side
Capsular pattern = pain at end range with arm overhead
What movements occur at the scapulothoracic “joint”?
Primary = Elevation/depression protraction/retraction upward/downward rotation Secondary = Anterior/posterior tilting internal/external rotation
Elevation/depression at scapulothoracic joint combines:
Elevation - combination of SC joint elevation and AC joint downward rotation (shoulder shrug)
Protraction/retraction at scapulothoracic joint combines:
Protraction - combination of SC joint protraction and slight AC joint IR
Upward/downward rotation at scapulothoracic joint combines:
Upward - summation of SC joint elevation and AC joint upward rotation
What are the bones which make up the glenohumeral joint?
Glenoid foass and head of humerus
What type of joint is the GH joint?
Ball and socket
What is angle of inclination in frontal plane of GH joint?
130-150 in frontal plane
What is angle of torsion in transverse plane of GH joint?
30 posterior
What is retroversion of GH joint?
Posterior orientation of humeral head with regard to condyles
Increased humeral retroversion may result in what changes in ER/IR ROM?
What athletes do we see this in?
Increased ER ROM
Decreased IR ROM
Dominant arm of throwing athletes which suggests retroversion may be 1 contributing factor for ROM adaptation (10-15 more)
How is the GH joint reinforced and stabilized?
Glenoid Labrum
- Enhances concavity and increase articular surface
- Resists humeral head translations, dissipates forces, and protects bony edges
- Attachment of GH ligaments and tendon of biceps long head
How is the GH joint reinforced and stabilized?
Joint Capsule
- Significant laxity, minimal stability
- Reinforced by thicker external lig
- Inferior portion is slack in adducted position creating axillary pouch
Tightness in posterior shoulder capsule may produce ________(dec/inc) anterior humeral head translation which in turn _____(dec/inc) subacromial space
- Increased
2. Decreases
What motions do the different ligaments limit at the GH joint?
Superior GH lig
- Limit ER and ant/inf translation at ) abduction
- Slackens when abducted beyond 35-45 degress
What motions do the different ligaments limit at the GH joint?
Middle GH lig
Limits anterior translation from 45-90 abduction and extremes of ER
What motions do the different ligaments limit at the GH joint?
Inferior GH lig
- Ant band - strongest/thickest
- Posterior band
- Axillary pouch
- Primary stabilizers beyond 45 degrees of abduction or with combined abduction and rotation
What motions do the different ligaments limit at the GH joint?
Coracohumeral lig
Limits inferior translation and ER of humeral head with arm hanging at side
Rotator Cuff
What does it do?
What 2 areas does the cuff not stabilize?
- Reinforces the GH joint capsule
- Protects and actively stabilizes GH joint with dynamic activities
Does not reinforce: - Inferiorly
- Region between subscap and supraspinatus (common dislocation site)
Describe the osteo of the GH joint.
Flex/ext
Add/Abd
ER/IR
Describe the arthrokinematics of the GH joint.
Spin
Roll
Sup/Inf glide
Ant/Post glide
Flexion/Ext of GH joint arthro:
Flexion = anterior roll, posterior glide
Ext = posterior roll, anterior glide
-Flexion causes tension through capsule
-Slight anterior translation may occur at end range flexion due to tension in posterior capsule
Add/Abd of GH joint arthro:
ADD = inferior roll, superior glide
ABD = superior roll, inferior glide
-Full abduction, ER will accompany
-Inferior GH lig tightens with abduction
ER/IR of GH joint arthro:
ER = posterior roll, anterior glide IR = anterior roll, posterior glide
What is the open pack position and capsular pattern for the GH joint?
Open pack = Abducted 55, then horizontally adducted 30, slight ER
Capsular pattern = ER > abduction > IR
Describe the scapulohumeral rhythm.
- Ratio of 2 degrees of GH. to 1 degree of scapular motion during arm elevation/abduction
- Abduction of 180 = 120 GH and 60 scapulothoracic
What is the ideal shoulder girdle posture?
- slightly elevated and relatively retracted scapula
- results in glenoid fossa facing slightly upward
What is the effect of gravity on scapulothoracic posture?
Results in depressed, protracted and excessively downwardly rotated scapula
Describe the impact of rounded shoulders on an individual’s shoulder complex.
-Slight depression, downward rotation and protraction of scapula
-Predisposes to shoulder impingement
Possible causes - general laxity, muscle tightness, abnormal cervicothoracic posture/habit
Describe how the rhomboids and low trap function together.
With retraction - elevation tendency of rhomboids neutralized by depression tendency of lower trap
Describe how the deltoid and supraspinatus function together.
Paralysis of deltoid - surpraspinatus able to perform full abduction of GH with decreased torque
Paralysis of supra - full abduction difficult but achievable
Describe how the serratus anterior, upper trap, and low trap function together.
Serratus anterior, UT and LT contract simultaneously to produce upward rotation during GH abduction
What is scapular winging?
-Having excessive amount of IR of the scapula with attempted elevation of the arm
Supraspinatus arthrokinematics on GH
- Drives superior roll of humeral head
- Compresses humeral head against glenoid
- Restricts excessive superior translation of humerus
Infraspinatus, teres minor, subscap arthro on GH:
Exert depression force on humeral head
Infraspinatus and teres minor arthro on GH
ER humerus
Describe how the infraspinatus and mid trap function together.
Middle trap acts to stabilize scapula while infraspinatus ER the shoulder
Rhomboids act synergistically with teres major during strong resisted ______
adduction
If middle trap was paralyzed, scapula would move into _______ rotation as the GH joint is ER which creates scapular ______
- internal
- dyskinesia
What is scapular dyskinesia?
- Any abnormal position or movement of the scapula
- Alters effectiveness of muscle actions and distorts arthrokinematics resulting in increased stress
