Shoulder complex Flashcards

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1
Q

What are the joints contributing to the shoulder complex

A

Acromioclavicular (AC)
Sternoclavicular (SC)
Scapulothoracic (ST)
Glenohumeral (GH)

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2
Q

what are the bones contributing to the shoulder comple

A

Scapula
clavicle
humerus
sternum

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3
Q

Describe the glenoid fossa and its orientation in good posture

A

-small and shallow
-diected anterior-laterally about 5*
-glenoid labrum and articular cartilage add depth
(articular cartilage is thinner on the inside)

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4
Q

What is the resting position of the scapula

A

-superior angle at T2
-root at T3
-inferior angle T8
-Medial border 5-6cm from midline
-35* anterior to frontal plane

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5
Q

describe the orientation of the clavicle

A

-acts as a strut-keeps scapula at a constance distance from trunk/thoracic
-20* posterior to the frontal plane

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6
Q

Describe the orientation of the humerus

A

-head faces medial
-incline 135* to shaft (superiorly)
-retroverted 30* posteriorly

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7
Q

articular surfaces of the GH joint

A

head of hummus with glenoid fossa of scapula
(1/3 of the humeral head contacts the glenoid fossa at any given time)

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8
Q

What is hilton’s law

A

a joint capsule has nerve supply from branches of the nerves that cross that joint (innervate the muscles that cross that joint)

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9
Q

Describe the GH
-capsule innervation
-overall ligament structure

A

-capsule is innervated by C5,6
-has a lax structure to allow for large ROM
~arm at side causes an inferior fold/slack
~can be distracted about 1 in

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10
Q

GH ligaments

A

coracohumeral
glenohumeral (Superior, middle, and inferior)

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11
Q

Coracohumeral ligament

A

-coracoid process to greater tuberosity
-limites external rotation and inferior translation (when you pull down on the humerus)
-limits flexion and extension at the extremes

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12
Q

Superior Glenohumeral ligement

A

Runs under coracohumeral
limits inferior translation
-limits external rotation at 0 degrees (what my arm is at my side)

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13
Q

Middle glenohumeral ligament limits

A

-limits external rotation at 0 and 45 * of abduction

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14
Q

Inferior GH ligament

A

-thickest
-2-3bands of the ligament
~superior (“2-4 O’clock”)
~axillary pouch
~posterior (“7-9 o’clock”)
-ligament is like a sling for the humerus
-limits ER at 90* of abduction/prevents anterior translation
-limits IR at 90* of abduction/prevents
posterior translation

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15
Q

GH capsule/ligament influence on kinematics

A

-ER produced posterior translation
-IR produced anterior translation
-capsule tension counters and reverses humeral head movement

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16
Q

where are the GH joint bursae

A

-subscapular bursa: deep to tendon of subscapularis
-subacromial bursa/sub deltoid: in the subscromial space

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17
Q

GH joint classifcation

A

-diarthrosis
-ball and socket: enarthroses
-triaxial
-three degrees of freedom

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18
Q

what are the osteokinematic motions of the GH joint and ROM

A

-flexion 0-180
-Abd: 0-180
-external rotation 0-90 (90 when abducted and 0-60 when at side)
-internal rotation 0-65 (90 when Abd)
-horizontal Add 0-120
-horizontal abd 0-45
-extension 0-50

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19
Q

injuries to the GH joint

A

-dislocation; most common is anterior/inferiorly (mechanism or injury forced horizontal abduction and external rotation)

20
Q

What are predisposing factors to a GH joint dislocation

A

-loose capsule
-small glenoid fossa
-no inferior musculature
-labrum does not provide a sufficient lip

21
Q

associated injuries with the GH joint

A

-tear in capsule and labrum (bankart lesion) an anterior inferior dislocation (anterior inferior tear of capsule and labrum “3-6” o’clock)
-fracture portion of humeral head (Hillsach’s lesion)
(impaction fracture)
-SLAP lesion: superior labrum anterior to posterior tear (“10-2 o’clock” on face of clock)

22
Q

What adds to the stability of GH joint

A

-dynamic musculature from the rotator cuff
-ligamentous: lax joint capsule does not provide much stability
-bony
-cohesion: synovial fluid bathes cartilage which adds cohesion
-intaarticular pressure in the closed capsule

23
Q

Sternoclavicular joint classification and shape of the bones at the joint

A

diarthrosis
saddle joint
biaxial/triaxial?
2-3 degrees of motion
(frontal plane has convex moving on concave/clavicle moving on sternum and transverse plane has concave moving on convex/clavicle moving on sternum)

24
Q

What are the SC joint ligaments

A

anterior and posterior sternoclavicular ligament
interclavicular ligament
costoclavicular ligament

25
Q

Anterior and posterior sternoclavicular ligament

A

-attaches from the clavicle to the sternum on the anterior and posterior side
-reinforces the joint capsule
-prevents an anterior/posterior displacement of clavicle that could occur during protraction/retraction of scapula
-prevents upward and lateral clavicle displacement during a downward roll and upward glide (doing depression of clavicle)

26
Q

describe the planes of the SC joint and their motions

A

-protraction/retraction are in the horizontal plane and the concave surface of the clavicle moves on the convex surface of the sternum
-elevation and depression are in the fontal plane and the convex surface of the clavicle moves on the concave surface sternum

27
Q

Interclavicular ligament

A

-runs from one clavicle to another in the sternal notch
-prevents excessive upward glide during clavicle during depression

28
Q

Costoclavicular ligament

A

-strong ligament that runs down and medial to 1st rub
-site of fulcrum of elevation/depression and protraction/retraction

29
Q

Are there any accessory structures in the SC joint if so explain?

A

articular disc
-reinforces the join t
-attaches superomedially to the upper aspect of sternal end of clavicle and inferolaterally to the first costocartilage
-supports the joint and prevents the medial clavicle from going superiorly
-resists force to dislocate clavicle medially
-increases the distance between the two articular surfaces for greater motion

30
Q

What are the osteokinematic motion so the SC joint

A

Protraction: anteriorly 0-30
Retraction: posteriorly 0-15
Elevation: superiorly 0-45
depression: inferiorly 0-10

Rotation:
-posterior: associated with elevation 0-40-50
-anterior: associated with depression back to neutral

31
Q

Characterize the AC joint
-other structures that might be present
-joint capsule

A

Plane synovial joint (flat surfaces the move on each other and sit at an angle- not a diarthrotial joint)
-little mobility between clavicle and acromion
-moves with scapula
-articular disc are sometimes incomplete
-joint capsule is thin and loose to allow sliding

32
Q

AC joint osteokinematic motions

A

-upward/downward rotation
-rotation adjustments in horizontal and sagittal plan

33
Q

AC joint arthrokinematic motions

A

gliding and sliding to adjust the clavicle

34
Q

AC joint ligaments

A

Coracoclavicular
-trapezoid
-conoid

35
Q

coracoclavicular ligaments

A

-prevent superior dislocation of clavicle on the distal end
-transmit forces from the scapula to the clavicle
-produce and limit longitudinal rotation of the clavicle

36
Q

AC joint injuries

A

Seperation: step off deformity
-scapula lifts down away from the clavicle so that the lateral end of the clavicle appears elevated (acromian gets driven below the distal clavicle) due to a shearing force

37
Q

Scapulothoracic joint

A

-not a true joint but rather a physiological joint
-extrinsic muscles of the shoulder
-maintain position of the scapula and produce the movements
-trapezius and serrates anterior provide major control of the scapula

38
Q

what are the osteokinematic motions of the ST joint

A

abduction (protraction)
adduction (retraction)
elevation
depression
rotation: superior(upward/lateral) /inferior (downward/medial)
tilting: around the medial lateral axis in the frontal plane

39
Q

what are the arthrokinematic motions of the ST joint

A

gliding or sliding
rotation

40
Q

explain the force couples produced at the glenohumeral joint during shoulder abduction

A

Force couple 1:deltoid and supraspinatus (and rotator cuff)
-accounts for 120* of total motion
-the rest of the rotator cuff will cause the inferior glide of the humeral head

Force couple 2: upward rotation of the scapula produced by the serrates anterior and trapezius
-accounts of the 60* of total motion

41
Q

Explain the scapula humeral rhythm
and its role for motion

A

-for every 2 degrees of GH there is 1 degree of ST
-occur simultaneously
-role:
1. limits active insufficiency of deltoid and supraspinatus
2. glenoid support for the humeral head
3. prevents impingement agasint the coracoacromian arch
4. provides stable base for intrinsics or muscles that cross the scapula and humerus

42
Q

Describe phase 1 of sacpulohumeral rhythm

A

-0-90*
-elevation of lateral end of clavicle occurs as scapula upwardly rotates about 30*
-elevation is limited by costoclavicular tautness medially

43
Q

describe phase 2 of scapulohumeral rhythm

A

-90-180*
-coracoclavicular ligament tightness producing posterior clavicular rotation
-scapular rotation is allowed to continue without further clavicular elevation

44
Q

what is the suprahumeral space and what is inside it

A

-interval between the head of the humerus and the coracoacromial arch
-also called the subacromial space
-contents (superficial to deep)
1. subacromial bursa
2. supraapsinatue tendon
3. super joint capsule
4. biceps brachii long head tendon

45
Q

Impingement syndrome

A

-painful arch 60-120* (during which there is the longest external moment arm where the rotator cuff must work the hardest to pull the humeral head down so it doesn’t pinch)
-irritation of supraspinatus tendon, biceps long head tendon, subdeltoid bursa infraspinatus tendon

46
Q

Impingement syndrome epidemiology (what can be factors that cause it)

A

-tightness of the inferior joint capsule therefore the hummus cannot go down
-weakness in the rotator cuff therefore it cannot pull down the humeral head or compress to allow for full motion
-timing: when they are calling on the muscles/retrain them to turn these muscles on during the correct time in the motion
-overuse: Rotation cuff gets tired so it will not cause the inferior glide

47
Q

What are signs of altered shoulder mechanics

A

-pain
-limited ROM
-limited force production
-Decreases quality of motion