Shoulder Test 2 Flashcards by Alexander Lee

GH accounts for __% of shoulder motion

ST accounts for __%

GH:66%

ST:33%

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How many degrees of freedom does the sternoclavicular joint have?

Elevation/depression
protraction/retraction
A/P rotation

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Elevation and depression of the sternoclavicular joint occurs between the….

Disc and clavicle

remember elevation/depression happens more distally on the joint

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Protraction and retraction of the sternoclavicular joint occurs between the….

Disc and manubrium

remember protraction retraction happens more proximally on the joint

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Anterior posterior rotation of the sternoclavicular joint occurs between the….

Clavicle and the costal cartilage of 1st rib

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The sternoclavicular joint consists of 2 synovial _____ joints

What are they?

Plane joints

Superior: between disc and medial clavicle

inferior: medial clavicle with manubrium and first costal cartilage

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What is the purpose of the sternoclavicular disc?

Increases joint congruence and absorbs force

creates two seperate joint cavities and acts as pivot during motion

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During elevation and depression of the sternoclavicular joint: the ______ rolls and glides on the _____

Clavicle on the disc

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during protraction and retraction of the sternoclavicular joint, the ____________ roll and slide on the _________

Clavicle and disc on the manubrium

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The anterior and posterior sternoclavicular ligament both limit ______

which is the primary?

Anterior/posterior translation

posterior ligament is the primary

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What ligament limits elevation of lateral clavicle and counteracts force of SCM/sternohyoid muscle

costoclavicular ligament

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What ligament resists excessive depression of clavicle and superior gliding of clavicle on manubrium

interclavicular ligament

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What is normal SC elevation?

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What is normal SC depression

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What is normal SC protraction?

15-20

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what is normal SC retraction?

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What is normal posterior rotation of the SC?

Anterior?

Posterior: 50

Anterior: 10

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During SC elevation: the lateral end of clavicle moves upward and the medial end rolls _______ and slides ______ on the sternum

rolls superiorly and slides inferiorly

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During SC depression, the Lateral end of clavicle moves downward
Medial end of clavicle rolls _______ and slides ________

rolls inferiorly and slides superiorly

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During SC protraction, the Lateral clavicle moves anteriorly in transverse plane
Medial clavicle roll and slide __________ on sternum

anteriorly

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During SC retraction: Lateral clavicle moves posteriorly
Medial clavicle roll and slide ____________

posteriorly

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During SC Elevation depression the roll and slide are ______

during SC protraction/retraction the roll and slide are _____

Opposite

Same

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SC Joint Stability facts

Incongruent but stable link to axial skeleton

Degenerative changes uncommon

Disc and ligament structures help to dissipate forces

Represent 1-3% of joint dislocations in body
subluxations may be more frequent

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What is the purpose of the AC joint?

Allows scapula to rotate during arm movement:

Increases UE motion

Positions glenoid beneath humeral head

Maximizes scapula contact to thorax

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The lateral clavicle's contact with the acromion is _____ in orientation and susceptible to ____ forces

Vertical Shear forces Note: This joint varys in congruence and configuration person to person, Variable disc at this joint that may or may not form

The AC joint has a ____ capsule and ____ ligaments

weak capsule strong ligaments

What is the purpose of the superior AC and inferior AC ligament

resists opposing forces inferior ligament is not as strong Note: these are reinforced by the deltoids and traps

What are the two parts of the coracoclavicular ligament?

Conoid Trapezoid

What is the purpose of the conoid ligament?

Resists inferior forces

What is the purpose of the trapezoid ligament

resist posterior translation Note: trapezoid is in the front so it can resist clavicule moving back

What is the critical role of the coracoclavicular ligament (both parts combined)

couple **posterior** clavicle rotation and scapula **upward rotation **during arm elevation

Internal and external rotation of the AC joint occurs at what axis? How much normal motion?

vertical Normally has 20-35 degrees

Anterior or posterior tipping of the AC joint normally occurs in what plane? How much motion does this normally have?

Oblique coronal axis 20-40

Upward and downward rotation of the AC joint occurs in what axis? how much motion?

Oblique AP axis upward: 30 downward: 17

What is the purpose of AC int/ext rotation? Anterior/posterior tipping? Up/down rotation?

Int/ext rotation- maintains scapular contact with curvature thorax ant/post tipping- maintains scapular contact with verticle curvature of thorax up/down rotation- tilts glenoid fossa up and down

How is the AC joint most commonly injured?

Fall on shoulder with arm adducted or contact sports - not a very stable joint, subject to degenerative changes

The scapulothoracic joint is dependent on...

movement at the AC and SC joints

What is normal scapular position?

2 inches from midline between ribs 2 and 7

How is the scapula normally oriented?

35-45 degrees internally rotated/protracted tilted anteriorly 10-15 degrees upwardly rotated 5-10 degrees

How much upward rotation of the scap is required for arm elevation?

Excessive ______ of the scapula causes winging

internal rotation

Review this chart

The GH joint has _ rotary and _ translatory degrees of freedom

3 and 3

The humeral head normally faces...

Medially, superiorly, and posteriorly

What is the normal angle of inclination and angle of torsion

inclination - 130-150 torsion- 30 posterior

The glenoid labrum enhances the concavity by...

50%

What 2 structures attach to the GH labrum?

Longhead of bicep tendon and GH ligaments

The GH capsule tightens during... how much distraction is normally possible?

Ext rotation + abd (90/90) 2.5cm note: capsule has x2 the surface area of the humeral head

What does the superior GH ligament resist?

Resists anterior and inferior translations of humeral head at 0 degrees abduction

What is the function of the middle GH ligament?

Prevents all types of translation from 0-60 abduction

What is the function of the inferior GH ligament?

3 components Anterior- resists ant/inf translation Posterior- resists post/inf translation Axillary pouch- resists inf translation

What ligament forms a tunnel for the longhead of bicep tendon to pass through?

Coracohumeral ligament

what are the 2 parts of the coracohumeral ligament?

First band: coracoid to supraspinatus tendon + greater tubercle Second band: coracoid to subscapularis + lesser tubercle

What muscle can be impinged at the coracoacromial arch

supraspinatus

What is inside of the subacromial space?

subacromial bursa, rotator cuff tendons, and tendon of long head of biceps

What is the purpose of the coracoacromial arch

Protects subacromial structures and prevents superior dislocation of humerus

What is normal flexion/extension and what axis does it occur in?

Coronal axis 120 50

ABd limited when in neutral or medial rotation by _______, ________ is required for full Abd

greater tubercle lateral rotation

During GH elevation, the humeral head rolls ______ and slides __________

superiorly inferiorly

If arm is loaded (like you’re carrying something at your side), _________ contracts May be more important that originally thought ↑ inferior subluxation with ↓ __________

supraspinatus ↑ inferior subluxation with ↓ rotator cuff function

Deltoid requires synergistic help from ___________ to produce desired rotation of humeral head

rotator cuff

Force vectors of middle deltoid: larger parallel (Fx) than perpendicular (Fy) component Majority of force from deltoid from rest position causes humerus to translate __________

superiorly

S.I.T.S perpendicular force component (Fy) causes some rotation of humerus but also compresses head into glenoid fossa Parallel force component (Fx) offsets _________ force from deltoid by pulling humeral head _______

superior inferior

What muscle has the largest MA for abduction?

supraspinatus

Can contribute to both flexion and abduction of shoulder Helps to reinforce superior GH joint, centering the head and reducing vertical and anterior shear May also tighten labrum **What muscle is this?**

Longhead of biceps

Joint reaction forces

All forces compress humeral head into glenoid fossa Can reach 9-10x the weight of UE when arm is elevated Greatest shear forces occur b/w 30-60˚ elevation

What tendon is most susceptible to degenerate changes?

Supraspinatus tendon painful arc 60-120

Shoulder abduction requires SC _____, _______ and _____

protraction, elevation, and posterior roll

shoulder adduction requires SC _____, _____, _____

retraction, depression, anterior roll back to neutral

What is the overall ratio of scapulohumeral rhythm?

2:1

Describe Scapulohumeral rhythm?

First 30- very little scapular movement middle portion- 1:1 ratio last portion: only GH motion

What muscles upwardly rotate the scap

Trap and serratus anterior

What happens at the SC/AC during 60 degrees of GH elevation

SC elevation -> Costoclavicular ligament becomes taut AC posterior roll -> Conoid and trapezoid (coracoclavicular) ligaments and costoclavicular ligaments are taut and prevent more elevation

What two delts work together for abduction?

ant and mid delt Note: supraspinatus has larger MA than delt at less than 60 degrees of abduction

Infraspinatus, teres minor, subscapularis Activity is greater in _______ than abduction

flexion

Rhomboids and levator scapulae do what?

Elevate and downwardly rotate scap

What muscles can depress the scap?

Latissimus Dorsi- Adduction, extension, and medial rotation of humerus + Adduction and depression of scapula Pectoralis Major Sternal Portion – depress GH and shoulder complex Pectoralis Minor- Assists both by directly depressing scapula through attachment to coracoid process Teres Major and Rhomboids- Strongly synergistic during adduction and depression of humerus Levator Scapular- Downward rotation of the scapula