The Shoulder Complex Flashcards
1
Q
Which joint is responsible for 2/3rd of shoulder motion?
A
Glenohumeral joint
2
Q
What joint is responsible for 1/3rd of shoulder motion?
A
Scapulothoracic joint
3
Q
What is the normal range of motion of elevation for the shoulder complex? How many degrees does the glenohumeral contribute? What about the scapulothoracic joint?
A
180º
120º
60º
4
Q
What bones make up the shoulder complex?
A
Clavicle
Scapula
Humerus
5
Q
Which 4 joints make up the shoulder complex?
A
Glenohumeral Joint
Sternoclavicular Joint
Acromioclavicular Joint
Scapulothoracic Joint
6
Q
What other motion is needed in order for shoulder elevation to occur? (Ipsilateral/contralateral) (cervical/thoracic/lumbar) (flexion/extension/sidebending/rotation)
A
Ipsilateral thoracic rotation
7
Q
What is the only structure that connects the axial skeleton to the shoulder?
A
Sternoclavicular joint
8
Q
How many degrees of freedom does the sternoclavicular joint have? What are those motions?
A
3 DoF
Elevation/Depression
Protraction/Retraction
Anterior/Posterior Rotation
9
Q
Between which 2 structures will elevation and depression of the sternoclavicular joint take place? (Disc/clavicle/manubrium/1st rib costocartilage)
A
Disc and Clavicle
10
Q
Between which 2 structures will protraction and retraction of the sternoclavicular joint take place? (Disc/clavicle/manubrium/1st rib costocartilage)
A
Disc and Manubrium
11
Q
Between which 2 structures will anterior and posterior rotation of the sternoclavicular joint take place?
(Disc/clavicle/manubrium/1st rib costocartilage)
A
Clavicle and 1st rib costocartilage
12
Q
Where is the articulation of the superior joint of the sternoclavicular joint?
A
Medial clavicle and disc
13
Q
Where is the articulation of the inferior joint of the sternoclavicular joint?
A
Medial clavicle with manubrium and first costal cartilage
14
Q
What happens at the SC joint during elevation and depression? (Relating to the clavicle and disc)
A
Clavicle rolls and glides on disc
15
Q
What happens at the SC joint during protraction and retraction? (Relating to the disc, clavicle, and manubrium)
A
The disc and clavicle roll and slide on the manubrium
16
Q
Which 4 ligaments surround the SC joint?
A
Anterior Ligament
Posterior Ligament
Costoclavicular Ligament
Interclavicular Ligament
17
Q
What motion does the anterior ligament in the SCJ limit?
A
Anterior/Posterior translation (posterior is the primary limiter)
18
Q
What motion does the posterior ligament in the SCJ limit?
A
Anterior/Posterior translation (posterior ligament is the primary limiter)
19
Q
What motion does the costoclavicular ligament in the SCJ limit?
A
Elevation of lateral clavicle
Counteracts superior pull of SCM and Sternohyoid muscles
20
Q
Which fibers of the costoclavicular ligaments run laterally?
A
Anterior fibers
21
Q
Which fibers of the costoclavicular ligaments run medially?
A
Posterior fibers
22
Q
What motion does the interclavicular ligament in the SCJ limit?
A
Excessive depression of clavicle
Superior gliding of clavicle on manubrium
23
Q
What structures does the interclavicular ligament protect?
A
Subclavian artery and brachial plexus
24
Q
How many degrees of elevation does the SCJ allow?
A
48º
25
How many degrees of depression does the SCJ allow?
15º
26
How many degrees of protraction does the SCJ allow?
15-20º
27
How many degrees of retraction does the SCJ allow?
30º
28
How many degrees of posterior rotation does the SCJ allow?
50º
29
How many degrees of anterior rotation does the SCJ allow?
10º
30
What happens to the medial end of the clavicle on the sternum during elevation? (Referring to rolling and sliding)
Rolls superiorly and slides inferiorly
31
What happens to the medial end of the clavicle on the sternum during depression? (Referring to rolling and sliding)
Rolls inferiorly and slides superiorly
32
What happens on the medial end of the clavicle on the sternum during protraction? (Referring to rolling and sliding)
Rolls and slides anteriorly
33
What happens on the medial end of the clavicle on the sternum during retraction? (Referring to rolling and sliding)
Rolls and slides posteriorly
34
What happens on the medial end of the clavicle on the sternum during posterior rotation? (Referring to the surface of the clavicle)
Inferior surface faces anteriorly
35
What happens on the medial end of the clavicle on the sternum during anterior rotation? (Referring to the surface of the clavicle)
Inferior surface returns to neutral (or more posteriorly)
36
What two structures does the ACJ attach?
Scapula and lateral clavicle
37
How many DoF does the ACJ have? What are they?
3
Internal/External Rotation
Anterior/Posterior Tilting
Upward/Downward Rotation
38
How many degrees of internal and external rotation does the ACJ allow?
20-35
39
How many degrees of anterior and posterior tilting does the ACJ allow?
20-40º
40
How many degrees of upward rotation does the ACJ allow?
30º
41
How many degrees of downward rotation does the ACJ allow?
17º
42
True or False: The AC capsule is a strong capsule
False; weak
43
How many AC ligaments are there? What are their names?
3 (4 if counting the coracoclavicular one as 2)
Superior AC
Inferior AC
Coracoclavicular (Made up of considerable ligament and trapezoid ligament)
44
What motions does the superior AC resist?
Opposing forces
45
What motions does the inferior AC resist?
Opposing forces (**Not as strong as the superior AC**)
46
What does the coracoclavicular ligament do?
Firmly unite the clavicle and scapula
47
What motions does the conoid ligament resist?
Resists inferior forces
48
What motions does the trapezoid ligament resist?
Resists posterior translation
49
What is the critical role of the coracoclavicular ligament?
Couple posterior clavicle rotation and scapula upward rotation during arm elevation
50
What is the most common way to injure the ACJ?
By engaging in contact sports or falling on shoulder with arm adducted
51
Which of the following is a functional joint rather than a true joint?
Scapulothoracic joint
52
For the scapulothoracic joint to move, which other joints must move as well?
AC, SC, or both
53
Where does the scapula naturally rest?
Scapula rests 2 inches from midline between ribs 2-7
54
In resting position, which way is the scapula shifted (protracted or retracted) and by how many degrees?
Internally rotated (protracted)
35-45º
55
In resting position, which way is the scapula tilted (anteriorly or posteriorly) and by how many degrees?
Tilted anteriorly
10-15º
56
In resting position, which way is the scapula rotated (upwardly or downwardly) and by how many degrees?
Upwardly rotated
5-10º
57
What are the rotary motions of the STJ?
Upward/Downward Rotation
Internal/External Rotation
Anterior/Posterior Tilting
58
What are the translatory motions of the SCJ?
Elevation/Depression
Protraction/Retraction (Abduction/Adduction)
59
How many degrees of upward rotation are required for arm elevation?
60º
60
In the STJ, what does excessive internal rotation cause?
Scapular winging
61
Which shoulder joint is the premier example of dynamic stabilization?
ST Joint
62
What kind of synovial joint it’s the GHJ?
Ball and Socket
63
How many degrees of freedom does the GHJ have?
3 rotary and 3 translatory
64
Size wise, how does the humeral head differ from the glenoid fossa?
The humeral head is larger than the glenoid fossa
65
The glenoid fossa can be retroverted or anteverted. What does this mean?
It is the bony orientation of the glenoid fossa. If the glenoid fossa is retroverted, that means that it is facing posteriorly. If it is anteverted, that means that it is facing anteriorly
66
Which way does the humeral head face, which relation to the glenoid fossa?
Head faces medially, superiorly, and posteriorly
67
What is the angle of inclination of the humeral head?
130-150º
68
What is the angle of torsion of the humeral head, and where direction does it face?
30º
Posteriorly
69
What does the glenoid labrum do to the glenoid fossa?
The glenoid labrum enhances the fossa concavity by about ~50%
70
What are all 5 functions of the glenoid labrum?
1. Enhance fossa concavity
2. Resist humeral head translations
3. Protect bony edges of fossa
4. Minimize GHJ friction
5. Dissipate joint contact forces
71
How do you tighten the GH capsule?
Abduction + Lateral Rotation (External rotation)
72
For which tendon does the glenoid labrum serve as an attachment site?
Tendon of the long head of bicep
73
How much distraction of the GHJ is possible in the loose packed position?
2.5 cm
74
Which direction is the GH capsule most commonly dislocated?
Anteriorly
75
How many ligaments are there in the GHJ, and what are they?
4
Superior GH Ligament
Middle GH Ligament
Inferior GH Ligament Complex
Coracohumeral ligament
76
How many ligaments is the inferior GH ligament complex composed of, and what are their names?
Anterior
Posterior
Axillary Pouch
77
What structure does the superior GH ligament help to form?
Rotator Cuff Interval
78
What motions does the superior GH ligament resist?
Resists anterior and inferior translations of the humeral head at 0º abduction
79
What motions does the middle GH ligament resist?
Prevents ANY translation of the humeral head from 0-60º of abduction
80
What motions does the anterior portion of the inferior GH ligament complex resist?
Resists anterior and inferior translation after 60º of abduction
81
What motions does the posterior portion of the inferior GH ligament complex resist?
Resists posterior and inferior translation after 60º of abduction
82
What motions does the axillary pouch portion of the inferior GH ligament complex resist?
Resists inferior translation after 60º of abduction
83
What do the two bands of the coracohumeral ligament form?
They form a tunnel for long head of biceps to pass through
84
Where is the first band of the coracohumeral ligament located?
Base of coracoid to edge of supraspinatus tendon and greater tubercle
85
Where is the second band of the coracohumeral ligament located?
Base of coracoid into subscapularis and lesser tubercle
86
What structures form the coracoacromial arch?
Coracoid, acromion, and coracoacromial ligament
87
What structures are contained in the subacromial space?
Subacromial bursa, rotator cuff tendons, tendon of long head of biceps
88
What is the function of the coracoacromial arch?
To protect subacromial structures, and prevent superior dislocation of the humerus
89
What can be a result of a type 3 coracoacromical arch?
Increased susceptibility to impingement
90
What can be a result of a type 4 coracoacromical arch?
Increased susceptibility to superior dislocation
91
How much flexion does the GHJ allow?
120°
92
How much extension does the GHJ allow?
50°
93
In what axis does GH flexion and extension occur?
Coronal
94
In what axis does GH medial and rotation occur?
Long axis
95
In what axis does GH abduction and adduction occur?
Anterioposterior axis
96
How much Abduction/Adduction does the GHJ allow?
90-120º
97
What motion of the GHJ is limited when in a certain position? And what is it limited by?
Abduction is limited when in neutral or medial rotation
Limited by the greater tubercle
98
In order for full abduction of the GHJ to occur, what following motion must also occur in the GHJ?
Lateral rotation
99
What can a tight capsule around the GHJ cause?
It could cause shifting of the humeral head during motion, or limit motion
100
What passive forces counteract the effects of gravity on the arm?
Rotator interval capsule
Capsular vacuum creates negative pressure
Lower glenoid + labrum tilt slightly upward
Passive tension of supraspinatus
101
Which muscle in the shoulder is “always on,” and what happens if it turns off?
The supraspinatus is always on. If it turns off, inferior subluxation occurs, which in turn reduces rotator cuff function
102
Which muscles are the prime movers for abduction in the GHJ?
Middle deltoid and supraspinatus
103
Which muscle is a prime mover for flexion in the GHJ?
Anterior deltoid
104
Which is a larger force vector of the middle deltoid? Parallel (Fx) or Perpendicualr (Fy)
Parallel (Fx)
105
The majority of force from the deltoid from resting position causes which directional translation in the humerus?
Superior
106
In order for the deltoid to produce desired rotation of the humeral head, which other synergistic muscles must activate?
Rotator cuff muscles
107
Name the 4 rotator cuff muscles
Supraspinatus
Infraspinatus
Teres minor
Subscapualris
SITSub
108
What is a dynamic stabilization function of the rotator cuff muscles, mainly the ITSub?
Compressing the head of the humerus into the glenoid fossa
109
The parallel force component (Fx) of the rotator cuff muscles offsets _______ translatory force from deltoid by pulling humeral head ______
Superiorly; Inferiorly
110
Which 2 rotator cuff muscles help with lateral rotation to clear the greater tubercle?
Infraspinatus
Teres minor
111
How does the long head of the biceps dynamically stabilize the GH?
Reinforces the GHJ by centering the head and reducing vertical and anterior shear
Also tightens labrum
112
At what angles is the greatest shear forces on the GHJ?
30-60º of elevation
113
Which tendon is the most vulnerable for degeneration or dysfunction in the GHJ?
Supraspinatus tendon
114
At which angles would you expect pain to be produced if there is degeneration of the supraspinatus tendon?
60-120º (the painful arch)
115
What are the main functions of scapulohumeral motion?
Distribute forces between the 4 joints, permitting more ROM with more stability
Maintains glenoid fossa in optimal position for humeral head -> decreases shear forces
Maintains good length-tension of humeral muscles preventing active insufficiency as scapula rotates up
116
How much abduction of the GH occurs before the ST kicks in?
30º
117
How much flexion of the GH occurs before the ST kicks in?
60º
118
Which 2 muscles kick in during clavicular elevation to upwardly rotate the scapula?
Trapezius and serratus anterior
119
Which ligament becomes taut during clavicular elevation?
Costoclavicular ligament
120
Which ligaments become taut during clavicular posterior rotation and work to prevent more elevation?
Coracoclavicular ligaments (conoid and trapezoid)
Costoclavicular ligaments
121
Which muscles work together to achieve elevation of the shoulder?
Deltoid
SITSub
Trapezius
Serratus Anterior
Rhomboids
Levator Scapulae
122
Which muscles work together to achieve depression of the shoulder?
Latissimus Dorsi
Pectoralis Major
Pectoralis Minor
Teres Major
Rhomboids
Levator Scapulae
Lower Trapezius
123
Which muscle has a constant MA through ROM, larger than deltoid for the first 60 degrees of abduction?
Supraspinatus
124
Which muscles’ activity in the shoulder is greater in flexion than in abduction when it comes to elevation of the shoulder?
ITSub
NOT SUPRA
125
Which muscles work together in order to elevate and downwardly rotate the scapula?
Rhomboids and Levator scapulae
126
Which muscles can eccentrically stabilize during upward rotation?
Rhomboids and Levator scapulae
127
Which portion of the pec major depresses the GH and shoulder complex?
Sternal portion
128
How does the pec minor work in depression of the shoulder?
Assists by directly depressing scapula through attachment to coracoid process
129
Which two muscles are strong synergists during adduction and depression of the humerus?
Teres major and rhomboids
