Week 10 Flashcards
four joints of the shoulder complex
Sternoclavicular
acromioclavicular
glenohumeral
scapulothoracic
Articulations involved in the shoulder complex
sternum clavicle ribs scapula humerus
What stabilises the sternoclavicular joint
anterior and posterior sternoclavicular ligaments
interclavicular ligaments
costoclavicular
articular disc
sternothyroid, sternohyoid, subclavius muscles
What is the primary purpose of the sternoclavicular joint
position scapula optimally to receive head of humerus
What stabilises the AC joint
Superior and inferior AC joint capsular ligaments
coracoclavicular ligament
articular disc
deltoid and upper traps
Role of the AC joint
Optimally align scapula against the thorax
add to scapula motion
Primary motions of the AC joint
upward and downward rotation
Secondary motions of the AC joint
horizontal & sagittal plan adjustments
Why is the AC joint inherently susceptible
sloped joint
high probability of large shear force
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
GH Type of joint
Multiaxial synovial ball and socket joint
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
What stabilises the GH joint
Joint capsule & capsular ligaments coracohumeral ligament glenoid labrum rotator cuff muscles long head of biceps
What are the 4 glenohumeral joint ligaments
superior glenohumeral ligament
middle glenohumeral ligament
coracohumeral ligament
inferior glenohumeralligament
Function of the superior glenohumeral ligament
restrainsinferior & AP translation of humeral head
Function of the middle glenohumeral ligament
provides anterior GH stability (esp 60 degree abd)
Limits extreme ER
Function of coracohumeral ligament
Taut in add
restrains inf translation + ER of HOH
what are the three parts of inferior glenohumeral ligament
3 Parts - ant band pos band and auxillary pouch
What is the function of the axillary pouch
taut at 90 degrees
acts as a sling supporting humeral head to resist inferior & AP translation
What is the role of the posterior band
taut at 90 degrees abd and EOR IR
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
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
what does the glenoid labrum do
increases fossa depth by 50%
improves stability by increasing contact with HOH
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
- scapulohumeral rhythm 2:1 - 120 degrees GH abduction + 60 degrees ST upward rotation
- 60 degrees upward rotation of scapula - simultaneous SC joint elevation + AC joint upward rotation
- clavicle retracts at SC joints
- Scapula posteriorly tilts and externally rotates
- 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
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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
