L&n 8 Shoulder Complex

Front 1

Define the bones of the shoulder complex

Back 1

clavicle, scapula, humerus

Front 2

Most mobile joint in the body

Back 2

glenohumeral joint

Front 3

Primary mechanism of stability in the UE

Back 3

Muscles; the arm is only connected to the axial skeleton at the SC joint

Front 4

Describe dynamic stabilization

Back 4

Situation where passive elements (bones, etc) provide little support and stability of structure is dependent on active muscle contraction forces.

Front 5

Advantages of dynamic stabilization

Back 5

Wide range of mobility, good stability when function is normal.

Front 6

Movement at the scapulothoracic interface is dependent on movement at what joint(s)?

Back 6

The stenoclavicular and/or acromioclavicular joints

Front 7

Relative contributions of the SC, AC and GH joints for movement of UE in flexion or abduction

Back 7

2/3 glenohumeral
1/3 SC and AC (scapular)

Front 8

List the main components of the sternoclavicular joint

Back 8

- medial clavicle with manubrium and first costal cartilage
- plane/mild saddle
- synovial
- 3 rotary degrees of freedom
- 3 translatory degrees of freedom
- capsule
- joint disk
- 3 major ligaments

Front 9

Describe the shape of the SC joint at rest

Back 9

wedge-shaped open superiorly

Front 10

Attachments at superior portion of medial clavicle

Back 10

- SC joint disck
- interclavicular ligament

Front 11

Attachments of the sternoclavicular disk

Back 11

- upper portion to postereosuperior clavicle
- lower portion to manubrium, 1st costal cartilage, anterior and posterior capsule
- Therefore, the disk acts like a hinge/pivot

Front 12

Position of strenoclavicular disk in the joint space

Back 12

Diagonally transects the SC joint space and divides into 2 cavities

Front 13

Describe different pivot points in sternoclavicular joint based on movement

Back 13

- elevation/depression clavicle: upper attachment as pivot
- protraction/retraction: lower attachment as pivot

Front 14

Axis of motion of the sternoclavicular joint

Back 14

At location of the costoclavicular ligament (lat and ant to joint)

Front 15

List the three major ligaments of the SC joint

Back 15

- sternoclavicular ligaments
- costoclavicular ligament
- interclavicular ligament

Front 16

Describe clavicular rotation with elevation and depression

Back 16

- elevation: lat clavicle rotates upward
- deperession: lat clavicle rotates downward

Front 17

Possible ROM at the SC joint

Back 17

- 50 degrees of elevation
- 15 degrees of depression
- 15 degrees protraction
- 20 degrees of retraction
- min/10 degrees of ant rotation
- 50 degrees posterior rotation
This ROM is usually not used functionally

Front 18

Describe clavicular rotation with protraction and retraction

Back 18

- protraction: lat clavicle rotates anteriorly
- retraction: lat clavicle rotates posteriorly

Front 19

From resting, which direction (in A/P) can the clavicle rotate around the long axis?

Back 19

Posteriorly (bring inferior surface anteriorly)

Front 20

Describe the balance of incongruence and joint degeneration in the sternoclavicular joint

Back 20

SC joint is incongruent BUT with disc matches well, dissipates force and RARELY have degenerative changes.

Front 21

SC joint dislocations represent what % of joint dislocations in the body?

Back 21

~1%

Front 22

The AC joint attaches...

Back 22

the scapula to the clavicle

Front 23

Describe the AC joint

Back 23

- plane
- synovial
- 3 rotational degrees of freedom
- 3 translational degrees of freedom
- joint capsule
- 2 major ligaments
- may or may not have a disk

Front 24

3 general purposes of the AC joint

Back 24

- allow additional rotation of scapula on thorax
- allow adjustments in tipping on thorax as arm moves
- transmission of forces from upper extremity to clavicle

Front 25

Describe the articular facets of the AC joint

Back 25

- incongruent
- large range and may be flat, concave-convex or reversed
- intra-articular mvnts at this joint are not predictable

Front 26

Describe relationship between AC joint facet shape and shear forces

Back 26

The more vertical the facet shape, the more prone to joint wear from shear forces.

Front 27

Describe the development (age2...) of the AC joint

Back 27

Fibrocartilaginous union until age 2. As UE is used the joint space develops and there may or may not be a "meniscoid" fibrocartilage remnant (disk) within the joint

Front 28

AC joint capsule strength

Back 28

It is weak

Front 29

3 ligaments of the AC joint

Back 29

- superior acromioclavicular
- inferior acromioclavicular
- coracoclavicular

Front 30

Why is the superior support of the AC joint better than the inferior?

Back 30

- fibers of superior AC ligament are reinforced by fibers of the deltoid and trapezius

Front 31

The clavicle and scapula are most most strongly connected by the

Back 31

coracoclavicular ligament; provides most of the joint's stability

Front 32

2 parts of the coracoclavicular ligament:

Back 32

- trapezoid laterally (more horizontal) resists posterior
- conoid medially (more vertical) resists sup/inf
- both limit upward rotation of the scapula at AC joint

Front 33

What separates the trapezoid and conoid ligaments of the AC joint?

Back 33

These are the 2 components of the coracoclavicular joint
- separated by adipose tissue and a large bursa

Front 34

Where on the clavicle does the coracoclavicular ligament attach?

Back 34

- undersurface
- the conoid attaches very posteriorly

Front 35

2 most important roles of the coracoclavicular ligament

Back 35

- Transfer forces from bearing weight on arm to strong SC joint
- coupling posterior rotation of clavicle to scapula rotation during elevation of upper extremity.

Front 36

Movements at the AC joint occur in relation to what?

Back 36

The plane of the scapula

Front 37

Helpful to focus on the position of _____ for external and internal rotation at the AC joint

Back 37

position of the glenoid fossa secondary to movement of scapula

Front 38

List 4 important reasons to maintain correct position of the glenoid fossa

Back 38

- maintain congruency with humeral head
- maximize function of GH muscles, capsule and ligaments
- maximize stability of GH joint
- maximize ROM of arm

Front 39

ROM at AC joint

Back 39

- 30 degrees of internal/external roation
- 30 degrees of ant/post tipping
- 30 degress of upward rotation
- 15 degree of downward rotation

Front 40

Describe the relationship between rotation of the scapula and rotation of the GH fossa

Back 40

They are the same; upward rotation of the scapula rotates the glenoid fossa up

Front 41

Upward/downward rotation of the scapula is limited by the

Back 41

coracoclavicular ligament

Front 42

Describe the process of the coracoclavicular ligament "allowing" the scapula to rotate upward

Back 42

- The coracoclavicular ligamnet attaches inferiorly and posteriorly on the clavicle.
- the clavicle rotates posteriorly
- the coracoclavicular ligament then has slack and allow the AC joint to "open up"

Front 43

Describe general progression of AC joint degeneration

Back 43

- degeneration starts in 20s
- joint space commonly narrowed in 60s

Front 44

Why is AC joint vulnerable to degeneration?

Back 44

Incongruent facets lead to high pressure per surface area

Front 45

General description of AC joint dislocation classification

Back 45

- graded on amount and direction of displacement
-Usually VI types
- Types I-III result from inferior displacement of the acromion from loss of support of coracoclavicular ligaments
- Type IV-VI injuries have posteriorly displaced lateral clavicle and are surgical

Front 46

% of residual symptom rates in non-surgical AC joint injuries

Back 46

40-70% (type I-type III) of people still have symptoms

Front 47

How to tell a person had an old type III unilateral AC joint dislocation

Back 47

On physical exam, the injured shoulder will have a step down to the acromion (relative clavicle is more superior)

Front 48

Is the scapulothoracic joint a closed chain or open?

Back 48

Closed; any movement at the scapulothoracic junction MUST cause movement at the acromioclavicular and/or the sternovclavicular joints.

Front 49

What is the resting position of the scapula

Back 49

- medial edge aprox 5 cm from midline
- internally rotated 40 degrees
- tipped anteriorly 15 degrees
- upwardly rotated 15 degrees from AC axis (or 2 degrees compared to vertebral line)

Front 50

What is the primary scapular motion that occurs at the AC joint?

Back 50

upward/downward rotation

Front 51

List the primary translatory motions of the scapula

Back 51

- elevation/depression
- protraction/retraction

Front 52

Does the scapula ever have a pure movement?

Back 52

No; the linkage to both the acromion and the clavicle prevents isolated movements.

Front 53

What is the primary movement of the scapula when the arm is elevated?

Back 53

upward rotation (of the scapula on the thorax)

Front 54

ROM of the scapula

Back 54

- 60 degrees of upward rotation
- others not well defined

Front 55

Shrugging the shoulders occurs primarily through what?

Back 55

Elevation of the clavicle at the SC joint; subtle changes in this joint also keep the scapula on the thorax during shrug

Front 56

Scapular protraction/retraction is a combination of what movements?

Back 56

- internal/external rotation at the AC joint
- protraction/retraction at the SC joint

Front 57

Upward rotation of the scapula is a combination of what movements?

Back 57

- elevation of the clavicle
- Posterior rotation at the SC joint
- Rotation at AC joint

Front 58

Anterior/posterior tipping of the scapula typically occur ______ and in association with _________

Back 58

- at the AC joint
- in association with ant/post rotation of the clavicle at the SC joint

Front 59

Stability of the scapula depends on

Back 59

- stability of SC and AC joints
- Muscle attachments pulling the scapula into the thorax

Front 60

Which is bigger: the glenoid fossa or the humeral head?

Back 60

The humeral head is bigger

Front 61

What is the most common orientation of the glenoid fossa in relation to the scapula

Back 61

7 degrees of retroversion (although may be larger or even anteverted)

Front 62

Which direction of the glenoid fossa is most curved?

Back 62

It is typically more curved in its LENGTH

Front 63

Shape of articular cartilage of the glenoid fossa

Back 63

- Increased radius of curvature over just bone
- Thinner in middle and thick at periphery of cartilage

Front 64

Proximal and distal components of the GH joint

Back 64

- proximal: glenoid fossa
- distal: the humeral head

Front 65

Shape of the humeral head

Back 65

1/3-1/2 of a sphere

Front 66

Where is the head of the humerus in relation to the shaft and humeral condyles?

Back 66

The head is medial, superior and posterior

Front 67

What is the angle of inclincation of the humerus

Back 67

- 130-150 degrees in the frontal plane
(axis through humeral head and neck in relation to longitudinal axis)

Front 68

What is the angle of torsion of the humerus?

Back 68

- 30 degree posteriorly
(angle through the humeral head and neck in relation to axis through the condyles)

Front 69

Why is posterior torsion of the humerus beneficial?

Back 69

Is helps match the resting GH joint from the internally rotated scapula

Front 70

Pitchers often have increased GH external rotation and decreased GH medial rotation. What is their likely retro/anteversion of the humeral head and what would they be at risk for?

Back 70

- humeral retroversion
- increased risk of posterior subluxation at end range

Front 71

What is the GH joint articulation like at rest?

Back 71

Little contact between joint surfaces; inferior humeral head rests on a small part of the inferior glenoid fossa

Front 72

The glenoid labrum attaches where and changes GH joint how?

Back 72

- Attaches around glenoid fossa
- Increases the depth of curvature by about 50%

Front 73

Describe basic difference between the glenoid labrum superiorly and inferiorly

Back 73

- superiorly: loose attaches
- inferiorly: firmly attached and relatively immobile

Front 74

What attaches to the glenoid labrum?

Back 74

- Tendon of the long head of the biceps brachii
- Glenohumeral ligaments

Front 75

Characteristics of GH capusle when arm is resting at side

Back 75

- large capsule
- taut superiorly
- slack anteriorly and inferiorly

Front 76

Size of the GH joint capsule compared to the humeral head

Back 76

Capsular surface area is twice that of the humeral head

Front 77

In the loose packed position, how much distraction of the humeral head is generally allowed

Back 77

2.5 cm

Front 78

What is the close-packed position of the GH joint?

Back 78

The humerus abducted and laterally rotated (joint capsule twists on itself)

Front 79

Where does the humeral head commonly sulux through anteriorly?

Back 79

* The foramen of Weitbrecht
An area of capsule between the superior and middle glenohumeral ligaments

Front 80

What muscle helps reinforce the GH capsule anteriorly?

Back 80

The subscapularis tendon

Front 81

Define and describe the rotator interval capsule.

Back 81

- Capsule of GH joint
- complex in the space between the supraspinatus and subscapularis tendons
- mad eof the upserior GH ligament, superior capsule and the coracohumeral ligament

Front 82

Important characteristics of the middle GH ligament

Back 82

- runs obliquely from the sup/ant labrum to the ant humerus
- blends with anterior capsule
- absent in 30% of subjects

Front 83

Define and describe the inferior glenohumeral ligament complex

Back 83

- called the IGHLC
- 3 components are the anterior band, axillary pouch, posterior band
- positional variation in function
- positional variation in viscoelastics

Front 84

The superior GH ligament (and thus the rotator interval capsule) limit:

Back 84

Anterior and inferior movements with arm at zero abduction

Front 85

The middle GH ligament limits:

Back 85

Anterior humeral translation with arm in 45 degrees of abduction

Front 86

The IGHLC stabilizes in what position:

Back 86

In abduction greater than 45 degrees and/or rotation
- reinforces when inferior capsule slack is used up
- external rot: anterior band fans out
- medial rot: posterior band fans out

Front 87

When arm is abducted, how does rotation effect the capsule?

Back 87

In all positions the capsule and GH ligaments tighten with rotation

Front 88

Describe the structure and function of the coracohumeral ligament

Back 88

- originates at the base of the coracoid process
- 2 bands: one to supraspinatus and greater tubercle; one to subscapularis and lesser tubercle
- 2 bands form a tunnel for long head of biceps brachii
- limits inferior translation of humeral head at rest
- prevents superior translation of humeral head especially when dynamic stabilizers are weak.
- resists external rotation when arm adducted

Front 89

What forms the coracoacromial arch

Back 89

coracoid process, acromion, coracoacromial ligament; often includes wtih inferior surface of AC joint

Front 90

What is in the coracoacromial arch

Back 90

- subacromial bursa
- rotator cuff tendons
- part of long head of biceps brachii

Front 91

Rotator cuff impingement is typically "impingement" of _________

Back 91

supraspinatus

Front 92

Radiographic features of the coracoacromial arch

Back 92

- measured from the acromion to the humerus
- 10mm at rest, 5mm with arm abducted

Front 93

People with shoulder impingement will often mention this about their sleep...

Back 93

Can't sleep on affected side (position forces the head of the humerus further into the space)

Front 94

2 most important bursae in the shoulder

Back 94

- subacromial and subdeltoid
- often continuous w/ each other
- separate the supraspinatus tendon and humerus from the other structures
- inferior part of bursae is superior supraspinatus tendon sheath
- does not normally communicate with the GH joint space

Front 95

ROM of the GH joint

Back 95

- 90 degrees (more with scapula)
- 45 degrees of extension
- med/lat rotation: 60 degrees in adduction, 120 degrees in abduction