Week 10 Flashcards by Matthew Russell

four joints of the shoulder complex

Sternoclavicular
acromioclavicular
glenohumeral
scapulothoracic

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Articulations involved in the shoulder complex

sternum
clavicle
ribs
scapula 
humerus

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What stabilises the sternoclavicular joint

anterior and posterior sternoclavicular ligaments
interclavicular ligaments
costoclavicular
articular disc
sternothyroid, sternohyoid, subclavius muscles

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What is the primary purpose of the sternoclavicular joint

position scapula optimally to receive head of humerus

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What stabilises the AC joint

Superior and inferior AC joint capsular ligaments
coracoclavicular ligament
articular disc
deltoid and upper traps

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Role of the AC joint

Optimally align scapula against the thorax

add to scapula motion

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Primary motions of the AC joint

upward and downward rotation

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Secondary motions of the AC joint

horizontal & sagittal plan adjustments

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Why is the AC joint inherently susceptible

sloped joint

high probability of large shear force

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Joint sprains of the AC joint GI-III

Gr I = damage to capsule & acromioclav lig
Gr II = rupture acromioclav & damage to coracoclav lig
Gr III = rupture acromioclav & coracoclavic ligs

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GH Type of joint

Multiaxial synovial ball and socket joint

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How much of the humeral head does the glenoid fossa articular surface cover

1/3

fit offers little to no stability
mobility favoured over stability

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What stabilises the GH joint

Joint capsule &amp; capsular ligaments
coracohumeral ligament
glenoid labrum
rotator cuff muscles
long head of biceps

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What are the 4 glenohumeral joint ligaments

superior glenohumeral ligament
middle glenohumeral ligament
coracohumeral ligament
inferior glenohumeralligament

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Function of the superior glenohumeral ligament

restrainsinferior & AP translation of humeral head

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Function of the middle glenohumeral ligament

provides anterior GH stability (esp 60 degree abd)

Limits extreme ER

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Function of coracohumeral ligament

Taut in add

restrains inf translation + ER of HOH

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what are the three parts of inferior glenohumeral ligament

3 Parts - ant band pos band and auxillary pouch

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What is the function of the axillary pouch

taut at 90 degrees

acts as a sling supporting humeral head to resist inferior & AP translation

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What is the role of the posterior band

taut at 90 degrees abd and EOR IR

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Role of the anterior band of the inferior glenohumeral ligament

strongest and thickest part of capsule
taut at 90 degrees abd and EOR ER
primary ligamentous restraint of ant translation of HOH
-both in neutral and abducted

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What stresses the anterior band

activities involving abduction and ER
e.g. the cocking phase of a baseball pitch
repetition of movement can stretch and tear the anterior band

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what does the glenoid labrum do

increases fossa depth by 50%

improves stability by increasing contact with HOH

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What causes anterior-inferior labral tear

rapidly anteriorly translating HOH

What does SLAP stand for

Superior labral tear

What causes a superior labral tear

large and/or repetitive forces produced by LH biceps | Limits ability of LH biceps to restrain HOH anterior translation

what does the coracoacromial arch comprise of

coracoacromial ligament and acromion space | - function roof of GH joint

what is the subacromial space

space between arch & HOH

What does the axillary nerve innervate

deltoid and teres minor

What does the thoracodorsal nerve innervate

latissimus dorsi

What does the upper subscapular nerve innervate

subscapularis upper fibres

What does the lower subscapularis innervate

subscapularis lower fibres and teres minor

What does the lateral pectoral nerve innervate

pectoralis major, occ pectoralis minor

What does the middle pectoral nerve innervate

pectoralis major (sternocostal head) , pectoralis minor

What does the suprascapular nerve innervate

Supraspinatus and infraspinatus

What does the subclavian nerve innervate

subclavius

What does the dorsal scapular nerve innervate

rhomboid major and minor, levator scapulae

What does the long thoracic nerve innervate

Serratus anterior

6 steps of full abduction of the shoulder

1. scapulohumeral rhythm 2:1 - 120 degrees GH abduction + 60 degrees ST upward rotation 2. 60 degrees upward rotation of scapula - simultaneous SC joint elevation + AC joint upward rotation 3. clavicle retracts at SC joints 4. Scapula posteriorly tilts and externally rotates 5. clavicle posterior rotates about its axis 6 GH joint externally rotates -- allows greater tubercle to pass posterior to acromion process - -supraspinatus contracts to ull superior capsule taut - -Auxillary pouch stretches to form sling for HO inferiorly

Role of Rotator cuff

provide structural reinforcement regulate dynamic joint stability actively control arthrokinematics

LH biceps brachii role

reinforces capsule rotator interval restricts ant translation of HOH Thoughts to resist superior migration of HOH

ST elevators

upper traps levator scapulae rhomboids

ST depressors

lower traps lats pec minor subclavius

ST protractor

serratus ant

ST retractors

middle traps lower traps rhomboids

ST upward rotators

Serratus ant | upper and lower traps

ST downward rotators

rhomboids | pec minor

What is throwers paradox

shoulder must be mobile enough to throw but stable enough to prevent injury

Injury risks of baseball pitchers

labrum vulnerable to injury - LH biceps ER at risk when shoulder decelerates

Stages of baseball pitch

``` -knee up (wind up) knee up - foot contact (stride) Foot contact - Max ER (arm cocking) Max ER - Release (Arm acceleration) Release - Max IR (Arm deceleraton) Max internal rotation - (follow through) ```

What is the wind up

initial movement to max knee lift of stride leg greatest activity = upper traps , serr ant, ant delt low RC activity forces and torques low

What is the stride phase

From end of balance to ground contact of lead foot - dramatic increase in shoulder muscle activity - - incl deltoids, suprasp, infrap SA & upper traps Scapula rotates up, elevates + retracts Shoulder abducts, ER +horiz abd

Stride phase

supraspin highest activity - abduct shoulder compress and stabilise GH joint Deltoid high activity

Arm cocking phase

lead foot contact to max shoulder ER

arm acceleration

Max sh ER to ball release

Phase 1 throwing rehab program

``` decrease pain and inflamm Normal ROM prevent muscle atrophy Dynamic stability Control functional stress/strain ( stop throwing ``` Exercises & modalities -ice, mobes, STT flexibility and stretching `

Phase 2 Throwing rehab

``` control flexibility progress strength restore muscle balance enhance dynamic stability core and LL strength ```

Phase 3 throwing rehab program

aggressive stretching progress neuromuscular control and proprioception improve strength power and endurance initiate light throwing

phase 4`

progress to throwing program return to competitive throwing continue strength and flexibility drills