Elbow Biomechanics Flashcards
1
Q
What joints make up the elbow (4)
A
- Humeroulnar
- Humeroradial
- Proximal radioulnar
- Distal radioulnar
2
Q
What is the shape of the radial head
A
More oval than spherical
3
Q
What are the points of articulation for the proximal radioulnar joint (2)
A
- Radial head
2. Radial notch of the ulna
4
Q
What are the points of articulation for the distal radioulnat joint (2)
A
- Ulnar head
2. Ulnar notch of the radius
5
Q
What does TFCC stand for
A
Triangular FibroCartilage Complex
6
Q
What type of joint are the humeroulnar and humeroradial joints
A
Hinge joint, uniaxial diarthrodial
7
Q
What motion occurs at the humeroulnar and humeroradial joints
A
Flexion and extension
8
Q
What type of joint are the proximal and distal radioulnar joints
A
Pivot joint (trochoid joint), uniaxial diarthrodial
9
Q
What motion occurs at the proximal and distal radioulnar joints
A
Supination and pronation
10
Q
True or False:
The joint capsule of the elbow is fairly large, loose, and weak anteriorly and posteriorly
A
True
11
Q
What are the sides of the capsule reinforced by
A
Ligaments
12
Q
What joints does the capsule enclose (3)
A
- Humeroulnar
- Humeroradial
- Proximal radioulnar
13
Q
Does the joint capsule enclosing 3 joints have any potential problems
A
Yes, there is the potential for cross contamination of infection
14
Q
What are the ligaments of the elbow (4)
A
- Ulnar collateral ligament (medial)
- Radial collaterla ligament (lateral)
- Annular ligament
- Interosseous membrane
15
Q
What are the 3 parts of the UCL
A
- Anterior
- Oblique
- Posterior
16
Q
Where does the anterior UCL run
A
Medial epicondyle to coronoid process
17
Q
What does the anterior UCL stabilize against
A
Valgus stress
18
Q
When does the anterior UCL protects the best
A
20-120 of flexion
19
Q
True or False:
We don’t need the anterior UCL to be effective at 0-20 due to the oleranon
A
True
20
Q
Where does the posterior UCL run
A
Medial epicondyle to ulnar coronoid process and olecranon
21
Q
What is the posterior UCL’s main function
A
Primary co-stabilizer against valgus stress at 120 flexion
22
Q
What is the posterior UCL’s secondary function
A
Secondary stabilizer at 30 and 90 flexion (NOT A RANGE)
23
Q
What are the other names for the oblique UCL
A
Transverse and Cooper’s
24
Q
Where does the oblique UCL run
A
Olecranon and coronoid process
25
What is the function of the oblique UCL
Helps hold down the anterior and posterior UCL
26
What happens because the oblique UCL holds down the anterior and posterior UCL ligaments
The oblique UCL helps maintain joint surface approximation
27
Where does the RCL run
Inferior lateral epicondyle to annular ligament and olecranon
28
What does the RCL resist (2)
1. Varus stress
| 2. Distractive forces of joint surfaces
29
What does the annular ligament do
Stabilizes head of radius to ulna`
30
What is it called when the radial head dislocates from the annular ligament
Nurse maids elbow
31
What is the shape of the annular ligament
Circular
32
Does the annular ligament and radial head have a perfect match
No
33
what is the interosseous membrane between
Radius and ulna
34
Which directions are the fibers of the interosseous membrane
Every direction
35
What does the fibers being in every direction do
Provides strength
36
What are the arthrokinematics of the humeroulnar and humeroradial joints
Concave on convex
37
What arthrokinematic motions occur with flexion and extension at the humeroulnar and humeroradial joints
Flexion: Anterior roll, Anterior glide
Extension: Posterior roll, Posterior glide
38
What are the arthokinematics of the proximal radioulnar joint
Spin of radial head on capitulum
39
Which way is the radial head longer when supinated
A-P
40
Which way is the radial head longer when pronated
M-L
41
What are the arthrokinematics of the distal radioulnar joint
Concave radius on convex ulna
42
What are the arthrokinematic motions of the distal radioulnar joint during pronation and supination
Pronation: Anterior roll, Anterior glide
Supination: Posterior roll, Posterior glide
43
Where is the axis of motion at the elbow joint
Fixed through the center of trochlea and capitulum
44
What projects more distal capitulum or trochlea
Trochlea
45
Is the axis of rotation at the elbow perfectly in the M-L axis
No
46
What is the average angle of the axis of rotation at the elbow
5-15
47
What is cubitus valgus
More than 15 carrying angle
48
What is cubitus varus
Less than 5 carrying angle
49
Who has a greater cubitus valgus males or females and why
Females due to the greater pelvic angle
50
What does cubitus mean
Elbow
51
What makes the carrying angle
The axis of motion at the elbow
52
How do you measure the carrying angle
Using the long axis of the humerus and ulna then take the angle made at the intersection of the lines
53
Why do you measure from the ulna and not center of the forearm
The ulna is fixed so the angle will not vary if measured from it
54
What is the normal carrying angle for men
5
55
What is the normal carrying angle for women
15
56
What motions cause the carrying angle to disappear
Pronation and full elbow flexion
57
Why does the carrying angle disappear with pronation and full elbow flexion
Change in the orientation of the forearm levers due to the radius gliding over the ulna
58
What is the open pack position
The position in which the joint capsule and ligaments have the greatest laxity
59
What is the close pack position
The position in which the joint capsule and ligaments are the most taut
60
True or False:
| The close pack position is most often the position where the most joint congruency occurs
True
61
What is normal elbow extension
0
62
How much hyperextension can a person have that is not pathologic
10-15
63
What is the end feel for elbow extension
Hard
64
What is the close pack position of the humeroulnar joint
Full extension
65
What is the open pack position of the humeroulnar joint
70 Flexion
66
What is the close pack position of the humeroradial joint
90 Flexion
67
What is the open pack position of the humeroradial joint
Full extension
68
Why is the humeroradial joint in the open pack position during full extension
The radial head should not have any contact with the capitulum of the humerus
69
What are the check reins to extension (3)
1. Olecranon process/fossa
2. Anterior capsule and anterior portion of collateral ligaments
3. Flexor muscle tension
70
What is normal AROM of elbow flexion
135-145
71
What is normal PROM of elbow flexion
150
72
What is the end feel for elbow flexion
Soft or hard
73
What are the check reins to elbow flexion (3)
1. Approximation of anterior musculature
2. Bony articulation
3. Passive stretch of triceps and posterior capsule
74
When dos approximation of anterior musculature occur first pronation or supination
Pronation
75
What are the primary movers of elbow flexion (3)
1. Biceps brachii
2. Brachioradialis
3. Brachialis
76
What are the secondary movers of elbow flexion (2)
1. Pronator teres
| 2. Wrist flexors
77
What determines the role of flexor muscles (6)
1. Location of muscles
2. Joint ROM
3. Forearm position
4. Magnitude of load applied
5. Type of muscular contraction
6. Velocity of movement
78
What is a spurt muscle
Mobility muscle
79
What type of muscle if the biceps brachii
Spurt muscle
80
What does a spurt muscle have
Increased rotary component and angle of pull
81
Where is the insertion of the muscle in relation to the axis of rotation
Close to the axis of rotation
82
Where is the MA of the biceps brachii the greatest
80-100 of elbow flexion
83
When is the biceps brachii most effective
Forearm supinated for power activities
84
Is the biceps brachii effective during both concentric and eccentric contractions
Yes
85
What type of muscle is the brachioradialis
Shunt muscle
86
What is a shunt muscle
Stabilizing muscle
87
Where is the insertion for a shunt muscle
Far from joint axis
88
True or False:
| Shunt muscles have a decreased rotary component and decreased angle of pull
True
89
Does the shunt muscle increase or decrease compressive force
Increase
90
Where is the moment arm of the brachioradialis greatest
Between 100 and 110 elbow flexion
91
When is the brachioradialis most effective
Neutral forearm position
92
True or False:
| There is slightly less pronation than supination of the forearm
True
93
What is the second most effective position of the brachioradialis
Full pronation because pronation is closer to neutral than supination
94
What type of muscle is the brachialis
Spurt muscle
95
What position is the brachialis most effective
All forearm positions
96
What position isolates the brachioradialis
Pronation of forearm
97
When is the moment arm of the brachialis grestest
100 elbow flexion
98
The brachialis is consider what of forearm flexion
Work horse
99
Which of the triceps muscles is a 2 joint muscle
Long head
100
Which of the triceps muscles is consider to be the work horse of extension
The medial head
101
What is the optimal length of the triceps muscles
30 elbow flexion
102
True or False:
| The triceps acts synergistically with biceps during resistive forearm supination
True
103
How does the triceps act synergistically with the biceps during resistive forearm supination
Prevents flexion of forearm by isometrically contracting
104
What is the main function of the anconeus
Initiate elbow extension
105
How does the anconeus initiate elbow extension
Draws posterior capsule posteriorly to prevent impingement of capsule
106
True or False:
| The anconeus has attachment to the posterior capsule and annular ligament
True
107
What is pronation of the forearm
85
108
What is supination of the forearm
90
109
What is the end feel of supination
Firm
110
What is the end feel of pronation
Firm or hard
111
What are the check reins to pronation of the forearm (4)
1. Radius over ulna
2. Posterior fibers of UCL
3. Posterior radioulnar ligament
4. Supinator
112
What are the check reins to supination of the forearm (6)
1. Anterior radioulnar ligament
2. Oblique cord of UCL
3. Pronator teres
4. Pronator quadratus
5. Interosseous membrane
6. Annular ligament
113
What is the open pack position of the proximal radioulnar joint
35 supination and 70 elbow flexion
114
What is the closed pack position of the proximal radioulnar joint
5 supination and elbow extended
115
What is the open pack position good for
Joint play, joint mobilizations, non thrust
116
What is the close pack position good for
Stabilization via CKC
117
True or False:
When a person is hypermobile we want them in the close pack position to promote osseous stability or capsuloligamentous intergrity
True
118
What is osseous stability
Greater joint congruency
119
What is the axis of rotation for the proximal and distal radioulnar joint
Longitudinal from radial head to ulnar head
120
During supination what is the orientation of the radius and ulna
Parallel
121
During pronation what is the orientation of the radius and ulna
Radius over ulna
122
Which way does the ulnar head move during pronation
Slightly distal and dorsal
123
Which way does the ulnar head move during supination
Slightly proximal and ventral
124
What is the primary mover for supination
Biceps Brachii
125
What is the secondary mover for supination
Supinator
126
When is the biceps brachii active during supination
When resistance is met and with increased speeds
127
Where is the biceps brachii most efficient
90 of elbow flexion
128
How does the supinator act
By "unwinding" pulls shaft and distal end of radius off the ulna
129
What angles is the supinator active in
All angles of elbow flexion
130
What work synergistically to cause supination (4)
1. Supinator
2. Biceps brachii
3. Triceps
4. Anconeus
131
What do the triceps and anconeus do for supination
Stabilize ulna
132
What is the primary mover of pronation
Pronator quadratus
133
What is the secondary mover of pronation
Pronator teres
134
When is the pronator quadratus active
With or without resistance at fast and slow speeds
135
Is the pronator quadratus affected by the position of the elbow
No
136
When is the pronator teres actively insufficient
Flexion of elbow and forearm pronation
137
What does radial hed and capitulum compression create
Stability
138
What causes lateral epicondylitis (2)
1. Repetitive use
| 2. Tensile stressing leading to microtears
139
What causes medial epicondylitis
Repetitive use
140
What muscle use causes lateral epicondylitis (1)
1. Extensor carpi radialis brevis
141
What muscle use causes medial epicondylitis (3)
1. Pronator teres
2. Flexor carpi radialis
3. Flexor carpi ulnaris
142
What is nursemaid's elbow
Radial head extraction from annular ligament
143
What causes nursemaid's elbow
Longitudinal traction (tensile) force
144
What does the cocking phase of throwing cause
Increased tensile stress throwing a ball
145
What type of stress does the cocking phase cause at the elbow
Valgus stress
146
Medial epicondylitis may lead to what
Increased carrying angle
147
Why does the carrying angle increase with medial epiconylitis
Adaptive lengthening of the UCL
148
Medial epicondylitis causes what to happen to the radial head and capitulum
Increased compression
149
What happens because of prolonged medial epicondylitis
Vascular compromise to articular cartilage and bone
150
What does vascular compromise result in
Avascular necrosis
151
Where does the radius and ulna fracture
Radius: Distal
Ulna: Proximal olecranon
152
What are the 2 types of radial fractures
1. Colle's
| 2. Smith's
153
Which way is a Colle's fracture
Posterior
154
Which way is Smith's fracture
Anterior
