Shoulder Biomechanics Flashcards
1
Q
How many degrees of freedom does the shoulder have
A
3… Can argue 4 (Horizontal ADD/ABD)
2
Q
Which ways does the UE elevate (3)
A
- Flexion
- Abduction
- Scaption
3
Q
What are the 7 motions of the UE
A
- Elevation
- ER
- IR
- Extension
- Adduction
- H ADD
- H ABD
4
Q
What is the amount of elevation of the UE
A
170-180
5
Q
What plane and axis does scaption occur in
A
Plane of the scapula and perpendicular axis
6
Q
What is the angle for the POS
A
30 degrees anterior to coronal plane
7
Q
What is ER at base of UE
A
40-60
8
Q
What is ER at 90 ABD
A
90-100
9
Q
What is IR at 90 ABD
A
45-60
10
Q
What motions occur with FIR (3)
A
IR, Ext, ADD
11
Q
What motions occur with FER (3)
A
ER, Flx, ABD
12
Q
What is normal FIR
A
Spinous process T5
13
Q
What is normal FER
A
Spinous process T3
14
Q
What is horizontal ABD of UE
A
120-140
15
Q
What is horizontal ADD of UE
A
40-60
16
Q
What is extension of the UE
A
60-80
17
Q
What position does the long head prevent the most motion
A
Elbow extension and pronation
18
Q
What are the 4 joints of the shoulder
A
- GH
- ST
- AC
- SC
19
Q
Where is the superior angle located in relation to spine
A
T2
20
Q
Where is the inferior angle located in relation to spine
A
T7
21
Q
What is the distance between spine of scapula and T3
A
2”
22
Q
What is normal upward rotation of scapula at rest
A
3-5 degrees
23
Q
Which rotation of the scapula is pathologic
A
Downward rotation
24
Q
Upward rotation promotes what
A
Inferior stability
25
What happens with a downward rotated shoulder
Adaptive lengthening
26
What ligaments are adaptively lengthened with downward rotated shoulder (2)
1. Superior GH
| 2. Coracohumeral
27
What is scapular dumping
Humeral head out of glenoid
28
What become tension loaded during scapular dumping (2)
1. Superior GH
| 2. Coracohumeral
29
What does scapular dumping potentially cause
False positive sulcus test
30
What is the surgery for inferior instability
Vest over pants
31
What does AMBRI stand for
Atraumatic Multidirectional Bilateral Rehabilitation and rarely requires Inferior capsular shift
32
What does TUBS stand for
Traumatic Unilateral with Bankart lesion requires Surgery
33
What position normally causes scapular dumping
Kyphotic psture
34
What is the anterior tilt of the scapula
9-20
35
What is another name for anterior tilt
Anteflexion
36
Does the anterior tilt of scapula increase or decrease with age
Increase
37
What does exaggerated thoracic kyphosis and/or an abnormally elevated scapula cause
Increased anterior tilt of scapula
38
How big is the subacromial space
5 dimes
39
What 3 things are housed in the subacromial space
1. RC muscles
2. Long head of biceps
3. Subacromial bursa
40
What type of impingement occurs at the subacromial space
External
41
How does anterior tilting effect impingement
Increases the chances of impingement
42
Where does internal impingement occur
Between humeral head and glenoid (posterior side)
43
What is the scapulo-clavicular angle at rest
50 degrees
44
What is the clavicular retraction angle at rest
20 degrees
45
What is the purpose of the scapula
Position the glenoid to allow optimal motion
46
What are the 5 motions of the scapulothoracic joint
1. Elevation/Depression
2. Protraction/Retraction
3. Upward/Downward rotation
4. Anterior/Posterior tilting
5. Medial/Lateral rotation
47
Do the motions of the scapulothoracic joint occur separate
No, they occur together
48
What occurs with scapular elevation
Clavicular elevation and anterior tilt of scapula
49
What occurs with scapular depression
Clavicular depression and posterior tilt of scapula
50
What occurs with scapular protraction
Clavicular protraction and medial rotation of the scapula
51
What occurs with scapular retraction
Clavicular retraction and lateral rotation of the scapula
52
What axis does sagittal plane motion occur about in the scapula
M-L axis at the AC joint
53
What axis does rotary motion occur about in the scapula
Vertical axis in region of AC joint
54
What does scapular winging result in
Posterior displacement of the medial border of the scapula
55
What causes scapula winging
Pathology of the serratus anterior
56
What causes pathology to the serratus anterior most commonly
Long thoracic nerve palsy
57
What clavicular motion occurs with upward rotation of the scapula
Elevation of the clavicle
58
What clavicular motion occurs with downward rotation of the scapula
Depression of the clavicle
59
What is the normal configuration of the AC joint
Convex clavicle and concave acromion
60
What type of joint is the AC joint
Synovial joint with fibrocartilage disc
61
What scapular motions occur with UE elevation
Elevation, anterior tilting, upward rotation, protraction, and medial rotation
62
What are the rotary scapular motions (3)
1. Anterior/Posterior tilting
2. Medial/Lateral rotation
3. Upward/Downward rotation
63
What type of joint is the SC joint
Synovial joint with articular disc
64
What SC joints movements occur with scapular motion (3)
1. Elevation/Depression
2. Protraction/Retraction
3. Posterior/Anterior tilting
65
What is the configuration of the clavicle and sternum in the frontal plane
Convex clavicle on concave sternum
66
What is the configuration of the clavicle and sternum in the sagittal plane
Concave clavicle on convex sternum
67
What 2 motions are you most likely to have trouble with at the sternoclavicular joint
Elevation and retraction
68
What is the amount of elevation at the SC joint
45
69
What is the amount of depression at the SC joint
15
70
What is the amount of elevation at the SC joint from full depression
60
71
What is the amount of protraction and retraction at the SC joint
15
72
Rotation of the clavicle occurs about what type of axis
Longitudinal axis
73
What type of clavicular motion occurs with scapular upward rotation
Posterior rotation and elevation
74
When does the posterior rotation of the clavicle occur during scapular upward rotation
After 30 degrees of elevation of outer clavicle
75
What is the max rotation of the clavicle
30-55
76
Is the anterior rotation of the clavicle
Not from anatomical neutral
77
GH joint analogy
GH joint = golf ball on a tee
78
What is the max amount of the humeral head that is in contact with glenoid
1/3
79
What is the shape of the glenoid fossa
Pear shaped
80
Where does the glenoid have greater concavity and dimension
Superior to inferior
81
Most common to least common dislocation of shoulder (3)
1. Anterior
2. Posterior
3. Inferior
82
Why are anterior and posterior dislocations more common than inferior dislocations
Due to decreased concavity of glenoid anterior to posterior
83
What is the angle of inclination of the humeral head
130-150
84
Which way does the humeral head face
Medially, superiorly, and posteriorly
85
Which way does the glenoid fossa face
Laterally, superiorly, and anteriorly
86
Is the glenoid and humeral head a perfect match
No 2/3 are perfect
87
What is GH ER at base
40-60`
88
What is GH ER at 90
90-100
89
What is GH IR at 90
45-60
90
What amount of elevation is the GH responsible for
0-120
91
Does the glenohumeral elevate the UE
No it is entire shoulder complex and scapulothoracic joint
92
For full UE elevation to occur what must happen
ER of humerus
93
What does ER of humerus do during UE elevation (2)
1. Prevents impingement of greater tuberosity against acromion
2. Provides greater humeral head articulating surface
94
What is the amount of glide with any UE motion
2mm
95
What is scapulohumeral rhythm
Humerus and scapula working together to provide smooth motion of UE
96
what is the ratio of humeral motion to scapular motion
2:1
97
What is it called when the scapula doesn't move properly
Scapulodiskinesis
98
What does scapulohumeral rhythm allow for (3)
1. Increase elevation ROM
2. Inferior stability of the GH joint
3. Maintain optimal length tension relationship for scapulohumeral musculature
99
How much flexion or scaption makes up phase 1A of UE elevation
Scaption: 0-30
Flexion: 0-60
100
True or False:
| The motion during phase 1A is predominantly GH motion
True
101
Where is the axis of rotation during phase 1A
Medial part of scapular spine
102
How much flexion or scaption occur during phase 1B UE elevation
Flexion: 60-90
Scaption: 30-90
103
True or False:
| In phase 1B there is consistent upward scapular rotation
True
104
Where is the axis of rotation during phase 1B
Line connecting root of the spine of scapula and SC joint
105
During phase 2A of UE elevation how much flexion and scaption occur
90-120
106
What happens to clavicular elevation during phase 2A
It tension loads costoclavicular ligaments
107
What is the limit of costoclavicular ligament elevation
30
108
As the clavicle elevation slows what happens to the axis of rotation
Shifts to the AC joint
109
How much flexion and scaption occur during phase 2B of UE elevation
120-end rang
110
Where is the axis of rotation during phase 2B
The AC joint
111
During phase 2B what is scapular upward rotation accompanied by
Coracoid depression
112
Why is scapular upward depression accompanied by coracoid depression
Anterior tilting of scapula
113
What does the depression of the coracoid process cause
Tension load to coracoclavicular ligaments
114
What does the tension of the coracoclavicular ligament do to the clavicle
Imparts a downward force on the posterior clavicle through conoid ligament
115
What does the downward force on the posterior clavicle cause
Posterior rotation of the clavicle
116
What does the clavicles crank shape result in
30 further elevation of the lateral clavicle
117
What does posterior clavicle rotation aid in
Scapular posterior tilting/tipping
118
What are the muscles that cause upward rotation of the scapula (4)
1. Upper trapezius
2. Lower trapezius
3. Upper serratus anterior
4. Lower serratus anterior
119
During phase 1B what causes upward rotation of the scapula (2)
1. Upper trapezius
| 2. Lower serratus anterior
120
During phase 2B what causes upward rotation of the scapula (2)
1. Lower trapezius
| 2. Lower serratus anterior
121
What is more important for abduction serratus or trapezius
Trapezius
122
What is more important for flexion serratus or trapezius
Serratus
123
With serratus paralysis what does abduction and flexion look like
Abduction: ROM may be full
Flexion: Reduced ROM
124
With trapezius paralysis what does abduction and flexion look like
Abduction: ROM to 75 degrees
Flexion: ROM may be full
125
How much upward rotation can the trapezius produce in the sagittal plane
20 degrees
126
In anatomical neutral what motion occurs at the humerus due to the deltoid
Superior translation
127
What helps start to UE elevation
Supraspinatus
128
How does the supraspinatus help start UE elevation
It compresses the humeral head into the glenoid giving the humeral head something to pivot around
129
What muscles help with inferior glide of the humeral head (3)
1. Subscapularis
2. Infraspinatus
3. Teres minor
130
True or False:
| If you have shoulder instability you should strengthen all of the RC muscle
True
131
What is the space below the coracoacromial arch and humeral head called
Outlet view for radiographs
132
What is the space used for
Look at space to determine if it is narrowed and if so are osteophytes or hooking of acromion present
133
Why do we get superior glide of the humeral head
RC pathology or adhesive capsulitis
134
What happens to the RC tendon when it is torn
Retract back toward origin
135
What 5 things provide stability to the GH joint
1. Negative intraarticular pressure
2. Labral concavity compression
3. Capsular constraint
4. Scapulohumeral muscle
5. Capsuloligamentou restraint
136
What is venting of the GH joint
Lose negative pressure effect due to puncture in the GH capsule
137
What does venting of GH joint produce
Immediate inferior subluxation
138
True or False:
| Full thickness RC tears can cause venting
True
139
With the labrum in contact the GH joint resists dislocation forces up to what percent of the compressive loads
64%
140
With the labrum removed how much does the resistance of dislocationdecrease
20%
141
What is a bony bankart
Avulse anterior labrum with bone
142
What muscles compress the humeral head into the glenoid cavity (4)
1. Deltoid
2. Supraspinatus
3. Infraspinatus
4. Teres minor
143
What percent of your body weight can the GH joint resist at 90 degrees of elevation when everything is intact
90%
144
What is cocontraction
Contracting muscles all the way around the joint
145
True or False:
| Closed chain allows for cocontraction
True
146
True or False:
| Scapulohumeral musculature aides in centering the humeral head in glenoid
True
147
When are the GH ligaments able to restrain translation
When osteokinematic motion takes slack out of the structur
148
Shoulder ligaments are stressed where
End range
149
What are stressed at mid range
Shoulder musculature
150
What is isometricity
There will always be some tension in the ligament no matter the range
151
What does end range osteokinematic motion do
Take slack out of a specific ligament or capsule
152
What happens when the ligament or capsule is passively tensioned
They contribute to an obligatory humeral head translation
153
Which way is the humeral head translation in relation to tensioned ligament or capsule
The opposite direction
154
What ligament or capsule is tension loaded during IR and which way is the translation
Posterior capsule is tension loaded and an anterior translation occurs
155
What are the 4 main capsuloligamentous structures of the GH joint
1. Superior GH ligament
2. Middle GH ligament
3. Inferior GH ligament
4. Coracohumeral ligament
156
What are the 3 parts of the Inferior GH ligament
1. Anterior band
2. Axillary pouch (accordion folder)
3. Posterior band
157
What is the main capsuloligamentous structures that provide stability during flexion
Anterior coracohumeral ligament
158
What is the main capsuloligamentous structures that provide stability during abduction
Inferior posterior capsule
159
What is the main capsuloligamentous structures that provide stability during IR
Middle posterior capsule
160
What is the main capsuloligamentous structures that provide stability during ER
Superior GH ligament
161
In anatomical neutral what is the primary stabilizer to ER and anterior head translation
SGHL
162
In anatomical neutral what is the secondary stabilizer to ER and anterior head translation
MGHL
163
True or False:
| There is a relative lack of support by the posterior capsule against posterior translation in anatomical neutral
True
164
What resists anterior humeral translation at 45 degrees of scaption
MGHL
165
True or False:
The posterior band of IGHL provides some capsule stabilization against posterior translation of humeral head at 45 degrees scaption
True
166
What stabilizes against anterior humeral head translation at 90 degrees of scaption
IGHL anterior band
167
What stabilizes against posterior humeral head translationat 90 degrees of scaption
IGHL posterior band
168
What happens to the anterior and posterior bands of the IGHL during IR
Anterior band goes below the equator
| Posterior band goes above the equator
169
What happens to the anterior and posterior bands of the IGHL during ER
Anterior band goes above the equator
| Posterior band goes below the equator
170
True or False:
| When there is a tear or laxity on one side will eventually cause laxity or a tear on the opposite side
True
171
What happens when you decrease the compressive force
You increase the shear force
172
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