Shoulder Arthrology Flashcards
1
Q
Which joint is made up of the clavicle acting like a strut holding the scapula?
A
Sternoclavicular (SC) joint
2
Q
Which joint firmly attaches the scapula to clavicle?
A
Acromioclavicular (AC) joint
3
Q
Which joint is not a true anatomic joint, but an interface between bones? Its movements are linked to the movements at the SC and AC, the position of the scapula provides the base for the GH joint.
A
Scapulothoracic joint
4
Q
Which joint is the most distal and mobile portion of the whole complex?
A
Glenohumeral joint (GH)
5
Q
A series of kinematic links cooperate to maximize range of motion; weakened painful or unstable link decreases the effectiveness of the entire UE
A
Shoulder Complex
6
Q
Superior slide of scapula in ____________
A
Elevation
7
Q
Inferior slide of scapula in _____________
A
Depression
8
Q
Medial border of the scapula slides anterior/lateral in ______________
A
Protraction
9
Q
Scapula goes posterior and medial during _____________
A
Retraction
10
Q
The inferior angle of the scapula rotates superior-lateral direction, glenoid fossa faces upward and UE is elevated during ________________
A
Upward rotation
11
Q
The inferior angle rotates inferior-medial direction and the UE is lowering during ___________
A
Downward Rotation
12
Q
What makes up the sternoclavicular joint?
A
Medial end of clavicle, clavicular facet on sternum, superior border of the cartilage of the first rib
13
Q
What does the basilar joint of UE do?
A
Links axial/appendicular skeleton
14
Q
Why does the sternoclavicular joint allow for large ROM?
A
Firmly attached
15
Q
The sternoclavicular joint is made of _________ ___________ tissues
A
Extensive periarticular
16
Q
What is the shape of the sternoclavicular joint?
A
Irregular saddle shaped, convex and concave with sternal facet reciprocally shaped
17
Q
The longitudinal diameters extend roughly in the_______ plane between the superior and inferior points of the articular surfaces
A
Frontal
18
Q
The _______________ diameters extend roughly in the horizontal plane between anterior and posterior points of the articular surfaces
A
Transverse
19
Q
What reinforces the capsule of the shoulder?
A
The anterior and posterior SC ligaments
20
Q
What are the components of the SC joint? (Ligaments, muscles, discs)
A
Anterior and posterior SC ligaments
Interclavicular ligament
Costoclavicular ligament
Articular disc (50% only)
SCM, Sternothyroid, sternohyoid, and subclavious muscle
21
Q
How many degrees of freedom in the SC joint?
A
3
Sagittal, frontal, and horizontal
22
Q
What does the SC joint do?
A
Elevates/depresses; protracts/retracts; rotates
23
Q
What is the goal of the SC joint?
A
To place scapula in optimal position for head of humerus
24
Q
What movements of the GH joint involve some movement at the SC joint?
A
All movements
25
When does the clavicle rotate in all 3 degrees of freedom?
UE elevation
26
What are the osteokinematics of shoulder elevation and depression?
Parallel to frontal plane
Axis is near anterior-posterior
35-45 degrees elevation
10 degrees degression
Clavicular motion produces similar in scapula
27
What are the arthrokinematics of elevation of the shoulder?
Convex surface rolls superiorly and slides inferiorly; CC ligament stretched and limits motion
28
What are the arthrokinematics of depression of the shoulder?
Convex surface rolls inferiorly and slides superiorly; interclavicular ligament/ superior portion of capsule stretches
29
What are the osteokinematics of SC protraction and retraction?
Occurs nearly parallel to horizontal plane
Axis - vertical
15-30 degrees each direction
associated with scapular protraction/retraction
30
Where are the arthrokinematics of protraction and retraction happening?
Occurs along SC joint's transverse diameter
31
What are the arthrokinematics of retraction?
Concave surface of clavicle rolls and slides posteriorly on convex surface of sternum; stretched anterior CC lig and anterior capsule
32
What are the arthrokinematics of protraction?
Occurs in an anterior direction, stretches posterior CC lig and posterior capsule, involves reaching forward
33
What are the osteokinematics of rotation of the clavicle?
Around the bone's longitudinal axis
UE elevation: posterior rotation 20-35 degrees
as UE returns clavicle returns
34
What are the arthrokinematics of axial rotation of the clavicle?
Spin of its sternal end relative to the lateral surface of the articular disc
Axial rotation is linked with the overall kinematics of flexion and abduction
35
What is the acromioclavicular joint connecting?
Lateral end of clavicle and acromion of scapula
36
What direction does the clavicular facet on the acromion face?
Medial and slightly superior
37
What type of disc is present in most AC joints?
Articular disc of varying forms
38
What is the capsule of the AC joint reinforced by?
Superior and inferior AC ligaments
39
What provides extrinsic stability for the AC joint?
Coracoclavicular ligament
40
What are the two parts of the coracoclavicular ligament?
Trapezoid ligament and conoid ligament
41
What are the kinematics of the AC joint?
* Subtle motions between scapula and lateral clavicle
* Optimizes the mobility and fit between scapula and thorax (GH joint)
42
What are the degrees of freedom of the AC joint?
3
43
What are secondary motions?
Rotational adjustment motions to fine tune and position the scapula
NOT USUALLY PERFORMED IN THE CLINIC
44
What does the upward rotation of the scapula at the AC joint look like?
Swings upward and outward relative to the end of the clavicle
- natural motion as part of elevation
45
How much upward rotation can we get?
Up to 30 degrees
46
What does downward rotation of the scapula at the AC joint look like?
Returning to anatomical position; frontal plane depicted but really scapular plane
47
What are rotational adjustment movements at the AC joint?
Pivoting or twisting type motions of the scapula around the lateral end of the clavicle
Optimally align the scapula against the thorax
48
What are the rotational adjustments in the horizontal plane? What axis?
Vertical axis, medial border moves away (internal rotation of glenoid fossa)
49
What are the rotational adjustments in the sagittal plane? What axis?
Medial-lateral axis, inferior angle pivots away (anterior tilting) or reverse (posterior tilting)
50
Wha happens to the AC joint during protraction?
Internally rotates in the horizontal plane; helps align the anterior surface of the scapula with the thorax curved surface
51
What happens to the AC joint during elevation?
Anterior tilting
52
Why is the scapulothoracic joint not a true joint?
No direct contact
53
Where is the scapula seated
between 2nd and 7th ribs. 6 cm lateral to spine
54
What degree of tilt, upward rotation, & internal rotation does the scapula have?
10 degrees of anterior tilt, 5-10 degrees of upward rotation, 30-40 degrees internal rotation
55
What is large UE ROM largely dependent on?
Scapular motion
56
What is protraction and retraction doing?
Protracting clavicle around SC joint, SC varies the amount of internal rotation
- Summation of horizontal motions at both SC and AC joint
57
What is upward and downward rotation made up of?
The summation of clavicular elevation and SC/Scapular upward rotation
58
What places the glenoid fossa in postion to support/stabailze the head of the humerus?
Upward and downward rotation
59
How many degrees is considered full upward rotation?
60 degrees
60
What is the shape of the head of the glenohumeral joint?
Large and convex
61
What direction does the fossa face in the GH joint?
Anterior
** lateral in scapular plane
62
What position is the head in in the GH joint?
Medially, superiorly, and posteriorly (Normal retroversion)
63
Where is the fibrous capsule?
Rim of glenoid fossa to anatomic neck
64
Describe the fibrous capsule's function?
Allows mobility
65
What are some characteristics of the fibrous capsule?
Loose fitting, thin and expandable
66
What is the fibrous capsule reinforced by?
External ligaments
67
What is it called when the inferior portion of the capsule is slackened in anatomical position?
Axillary pouch
68
Where is the synovial membrane in the shoulder?
Lines inner wall
69
What lines the intracapsular portion of the tendon of the LHB as it exits into the intertubercle groove?
An extension of the synovial membrane
70
What are both the head of the humerus and the glenoid fossa lined with?
Articular cartilage
71
What is the potential volume of space in the GH joint?
Up to 2 x the size of the humeral head
72
What stabilizes the GH joint?
Embedded ligaments provide passive tension
73
What are active forces of the GH joint produced by?
Local muscles -- specifically the rotator cuff
74
What crosses superiorly over the head of the humerus?
LHB
75
Describe glenohumeral capsular ligaments?
Fibrous connective tissue, interlacing collagen fibers
76
What do the capsular ligaments of the GH joint do?
Limit extremes of rotation and translation, helps keep a negative intra-articular pressure in the GH joint
77
What is the role of the superior GH capsular ligament?
Resist external rotation, inferior and anterior translations
78
What is the role of the middle GH capsular ligament?
Stabilizes most motions- esp anterior restrain in 45-90degrees of abduction and extremes of external rotation
79
What is the role of the inferior bands of the GH capsular ligaments?
supports the suspended humeral head and resists inferior/ anterior-posterior translations
80
How many portions of the inferior bands of GH capsular ligament are there? where are they taut?
3
Taut in 90 degrees of abduction
81
What does the coracohumeral ligament connect?
Coracoid process and the greater tubercle
82
What does the coracohumeral ligament blend with?
Superior capsule and supraspinatus tendon
83
When is the coracohumeral ligament taut?
In anatomical position
84
What does the coracohumeral ligament restrain?
Inferior translation and external rotation of the humeral head
85
Where does the superior GH ligament attach on the humerus?
Anatomic neck
86
When is the superior GH ligament taut?
External rotation, inferior and anterior translations of the humeral head
87
What is the distal attachment of the middle GH ligament?
Anatomic neck, blends with subscapularis tendon
88
What makes the GH ligament taut?
Anterior translation of humeral head with abduction, external rotation
89
Where is the distal attachment of the inferior GH ligament?
Anatomic neck
90
When is the inferior GH ligament taut?
90 degrees of abduction
91
Where is the distal attachment of the coracohumeral ligament?
Anterior side of greater tubercle, blends with superior capsule and supraspinatus tendon
92
What makes the coracohumeral ligament taut?
Inferior translation of the humeral head, external rotation
93
What do the rotator cuff muscles do?
Provide structural support for the capsule
94
Which rotator cuff muscle is the thickest?
Subscapularis
95
Where are the 2 regions of vulnerability of the rotator cuff?
- rotator cuff interval inferior to the supraspinatus and subscapularis
96
What reinforces the rotator cuff interval?
Long head of the biceps, coracohumeral ligament, and the superior/middle capsular ligaments
97
Where is the origin of the long head of the biceps?
Supraglenoid tubercle and labrum
98
What does the long head of the biceps restrict?
Anterior translation of humeral head
99
What does the force generated through the tendon of the long head of the biceps resist? When is it needed?
Anterior translation, needed in abduction
100
What is the glenoid labrum?
Fibrocartilaginous ring
101
What creates 50% of the depth of the glenoid fossa?
Glenoid labrum
102
What is the job of the glenoid labrum?
Stabilizer
103
What structures deepen and reinforce the GH joint?
joint capsule / GH capsular ligaments
Coracohumeral ligament
rotator cuff muscles (SITS)
Long head of the biceps
Glenoid labrum
104
What do superior capsular structures (SCS) provide the shoulder?
ligamentous support
105
What can disruption and deformation of the superior capsular structures (SCS) produce?
Humeral head can drift inferiorly - leads to subluxation or dislocation
106
What is the coracoacromial arch formed by?
Coracromial ligament and acromion process
107
What is depth of the the coracoacromial arch with the arm at rest by the side?
1 cm in adults
108
What is in the coracoacromial arch?
Supraspinatus muscle, subacromial bursa, long head of the biceps, and superior capsule
109
Where are the bursas generally around the GH joint?
Situated where significant frictional forces develop such as between tendons, capsule and bone, muscle and ligament, or 2 adjacent muscles
110
How many bursa are superior to the humeral head?
2
111
Where is the subacromial bursa? What does it do?
Above supraspinatus
protects supraspinatus from acromial bone
112
What does the subdeltoid bursa do?
Limits friction forces between deltoid and SS tendon/humeral head
113
How many degrees of freedom in the shoulder?
3
114
How many degrees is anatomic position of the shoulder?
0
115
Describe abduction kinematics?
Rotation of the humerus in the frontal plane
AP axis
convex head of humerus rolls superiorly, slides inferiorly
116
Describe adduction kinematics?
Convex head of humerus rolls inferiorly, slides anteriorly
AP axis
117
Why does the larger head not fall off during abduction and adduction?
Sliding
118
What stretches the axillary pouch?
the humeral head in 90 degrees abduction
119
What is the height of the subacromial space at 20 degrees of abduction?
7.5 mm
120
What is the height of the subacromial space at 85 degrees of abduction?
2.6 mm
121
What is the height of the subacromial space at 150 degrees of abduction?
5mm
122
Where is the SS potentially compressed in abduction? (Degrees)
35-70 degrees
123
What is adhesive capsulitis?
Excessive thickening or stiffness in ICL
124
What does adhesive capsulitis limit? Why?
slide of humeral head, jams against coracoacromial arch
125
How many degrees can the humeral head move without any slide?
22 degrees
126
What is impingement syndrome?
Unnatural and repeated compression/ abrasions damages the SS tendon, subacromial bursa, or superior parts of the capsule
127
What syndrome can repeated compression lead to?
Impingement syndrome
128
What is flexion arthrokinematics?
Rotation of the humerus in the sagittal plane, med-lateral axis
129
How many degrees of flexion are typical?
120 degrees GH
180 complex
130
How many degrees of extension are typical?
65 degrees active
80 degrees passive
131
What does the scapula do during extenion?
Anterior tilt
132
What are the degrees of internal rotation in neutral?
75-85
133
What are the degrees of external rotation?
60-70 degrees
134
What is the roll and slide with external rotation?
Rolls posteriorly and slides anteriorly
135
What is the roll and slide for internal rotation?
Rolls anteriorly, slides posteriorly
136
What is 90 degrees of abduction external rotation primarlly?
Spinning
137
What is the first kinematic principle of shoulder abduction?
active shoulder abduction of 180 degrees occurs as a result of simultaneous 120 degrees of GH joint abduction and 60 degrees of scapulothoracic upward rotation
138
What is the second kinematic principle of shoulder abduction?
The 60 degrees of upward rotation of the scapula is the result of a simultaneous elevation at the SC joint and rotation at the AC joint
139
What is the third principle of shoulder abduction?
the clavicle retracts at the SC joint
140
What is the fourth kinematic principle of shoulder abduction?
The upwards rotating scapula posteriorly tilts and externally rotates slightly with full shoulder Abd
141
What is the fifth kinematic principle of shoulder abduction?
The clavicle posteriorly rotates around its own axis
142
What is the sixth kinematic principle of shoulder abduction?
The GH joint externally rotates
143
What is scapulohumeral rhythm?
Natural rhythm between GH abduction and scapulothoracic upward rotation
144
When is the scapulohumeral rhythm constant?
after 30 degrees of abduction
145
What is the ration for scapulothumeral rhythm?
2:1 - every 3 degrees abduction = 2 degrees at GH joint and 1 degrees at scapulothoracic for upward rotation
146
What is the ration for the full arc of 180 regarding scapulohumeral rhythm?
120 GH / 60 ST
147
What is the 60 degrees of the scapula a result of (think SC and AC joints)?
elevation of the clavicle at the SC joint and upward rotation of the scapula at the AC joint
148
how many degrees does the sternoclavicular joint elevate during 180 degrees of full abduction?
30 degrees
149
What does the clavicle do at the SC joint during full abduction
Retracts 15-20 degrees
150
What plane does the clavicle move in during full abduction?
frontal plane
151
What does the scapula do at full abduction?
Tilts posteriorly and slightly rotates outward
152
What is the position of the scapula at rest (degrees)?
Anterior tilted 10 degrees
internally rotated 30-40 degrees
153
What does the scapula do with abduction (degrees)?
Posteriorly tilts 20 degrees
rotates AC and SC joints
154
What does the posterior tilting and external rotation of the scapula help with during abduction?
Keeps scapula flush with thorax, orients the fossa, moves the coracoacromial arch away from humeral head
155
How many degrees does the clavicle rotate posteriorly during full abduction?
20-35 degrees
156
What can cause reduced rotation of the clavicle during abduction?
Subacromial impingement
157
Which muscle makes the coracoclavicular ligament taut with scapular upward rotation?
Serratus anterior
158
What does the humerus naturally do during abduction
externally rotates
159
What does the rotation of the humerus during abduction allow for?
The greater tubercle to pass posterior to the acromion
160
What is the range for the external rotation of the humerus during abduction? (degrees)
25-50 with the majority before 70-80 degrees of abduction
