Elbow/forearm Flashcards
(109 cards)
1
Q
What it normal cubitus valgus?
A
15 degrees angle from longitudinal axix
2
Q
What is excessive cubitus valgus?
A
20-25 degrees deviated laterally
3
Q
What is gun stock?
A
Cubitus varum where forearm is deviated midline 5 degrees
4
Q
What can cubitus valgus damage if overstretched?
A
ulnar nerve
5
Q
What reinforces the articular capsule?
A
oblique bands of fibrous tissue
6
Q
What does the medial collateral ligament consist of?
A
anterior, posterior and transverse fiber bundles
7
Q
Which ligaments: anterior, posterior, transverse, are the strongest?
A
anterior
8
Q
Which fibers provide most significant resistance against valgus force?
A
anterior
9
Q
Where to anterior fibers arise and insert?
A
anterior part of medial epicondlye
medial part of coronoid process of ulna
10
Q
Why are some anterior fibers taut throughout sagittal plane movement?
A
fibers span both sides of axis of rotation
11
Q
What do anterior fibers provide?
A
articular stability throughout entire ROM
12
Q
Where do posterior fibers attach and insert?
A
- posterior part of medial epicondyle
- medial margin of olecranon process
13
Q
What do posterior fibers resist?
A
valgus force
14
Q
Transverse fibers insert and attach
A
cross from olecranon to coronoid process of ulna
15
Q
What are dynamic medial stabilizers of the elbow?
A
proximal fibers of wrist flexor and pronator group of muscles also resist excessive valgus-producing strain at elbow, most notably by flexor carpi ulnaris
16
Q
How can anterior capsule be injured?
A
excessively hyperextended
17
Q
The MCL is susceptible to injury from what?
A
valgus-producing forces to elbow in non–weight-bearing activities, such as pitching baseball and spiking volleyball
18
Q
The lateral collateral ligament complex is composed of what?
A
radial collateral ligament
lateral (ulnar) collateral ligament
19
Q
Where does the lateral collateral ligament originate?
A
lateral epicondyle and immediately splits into two fiber bundles
20
Q
Where does the radial collateral ligament go?
A
fans out to blend with annular ligament
21
Q
Where does the lateral ulnar collateral ligament attach?
A
distally to supinator crest of ulna
22
Q
The fibers of the LCL become taut during what action?
A
full flexion
23
Q
Why are the lateral collateral ligament and anterior fibers called “guy wires?”
A
provide medial-lateral stability to ulna during sagittal plane motion
24
Q
LCL complex and posterior-lateral aspect of capsule are primary stabilizers against what?
A
varus-producing force
25
Rupture of the elbow cause what?
- increase varus adduction
| - increase posterior-lateral rotary instability
26
What can instability of LCL be expressed as?
-excessive external rotation with subsequent subluxation of both humero-ulnar and humeroradial joints
27
What motion increases tension of MCL (anterior fiber)?
valgus
| extension and flexion
28
What motion increases tension of MCL (posterior fiber)?
valgus
| flexion
29
What motion increases tension of radio collateral ligament?
varus
| external rotation
30
What motion increases tension of lateral (ulnar) collateral ligament?
varus
| external rotation and flexion
31
What motion increases tension of annular ligament?
direction of radius, external rotation
32
What are the primary valgus or varus stabilizers?
- anterior fibers of MCL
| - lateral (ulnar) collateral ligament
33
What is maximal range of passive motion to elbow?
5° beyond neutral (0°) extension through 145° of flexion
34
What is the functional arc of motion
b/w 30° and 130° of flexion
35
What articulates the humero-ulnar joint?
concave trochlear notch of ulna and convex trochlea of humerus
36
Hyaline cartilage covers about _____ of articular surface on trochlea, compared with only ____ on trochlear notch
300°, 180°
37
What limits motion of humero-ulnar joint within sagittal plane?
natural congruency and shape of joints
38
What is required for humero-ulnar joint to be fully extended?
extensibility required in dermis anterior to elbow, flexor muscles, anterior capsule, and anterior fibers of medial collateral ligament
39
What can limit full extension?
excessive ectopic bone formation around olecranon
40
What does full extension require?
that prominent tip of olecranon process become wedged into olecranon fossa
41
In a health humero-ulnar joint, what stabilizes extension?
articular congruency and ↑ tension in stretched connective tissues
42
What is the action of the humero-ulnar joint during flexion?
concave surface of trochlear notch rolls and slides on convex trochlea
43
What can lead to neuropathy?
Stretching of ulnar nerve from prolonged or repetitive elbow flexion activities
44
What does full elbow flexion require?
elongation of posterior capsule, extensor muscles, ulnar nerve and certain portions of collateral ligaments, especially posterior fibers of MCL
45
How to severe elbow injuries effect the humero-ulnar joint?
trochlear notch of ulna may dislocate posterior to trochlea of humerus
46
How is the humeroradial joint articulated?
b/w cuplike fovea of radial head and reciprocally shaped rounded capitulum
47
How to flexion and extension affect the humeroradial joint?
consist of fovea of radius rolling and sliding across convexity of capitulum
48
Where is the medial lateral axis of rotation during humeroradial joint flexion?
center of capitulum
49
What structures are stretched taut during humeroradial joint flexion?
- posterior capsule
| - lateral (ulnar) collateral ligament
50
What structures are slackened during humeroradial joint flexion?
anterior capsule
51
What binds the radius and ulna together?
interosseous membrane and proximal and distal radio-ulnar joints
52
Where does forearm rotation occur?
an axis of rotation that extends from radial head through ulnar head—an axis that intersects and connects both radio-ulnar joints
53
What binds the radius and ulna together?
interosseous membrane and proximal and distal radio-ulnar joints
54
What does the set of radio-ulnar joints allow?
the forearm to rotate into pronation and supination
55
Where is the axis of rotation in forearm rotation?
axis extends from radial head through ulnar head-an axis that intersects and connects both radio-ulnar joints
56
In full supination the radius and ulna are ________?
parallel
57
Moving into full pronation, the radius______?
crosses over the ulna
58
Where does the axis of rotation extend when in pronation?
obliquely across forearm from radial head to ulnar head
59
What forms the distal segment in the forearm complex?
radius and carpal bones
60
What forms the proximal segment in the forearm complex?
humerus and ulna
61
Where does the thumb stay during pronation?
with the radius
62
What is the zero reference position of the forearm?
thumb up position midway between complete pronation and supination
63
What is the average forearm rotation?
75 degrees of pronation and 85 degrees of supination
64
How much rotation do ADL require?
100 degrees of rotation, 50 of that from pronation and 50 from supination
65
A decrease in pronation and supination can be compensated for by what?
internally and externally rotating the shoulder
66
Pronation and supination require simultaneous movements where?
proximal and distal radio-ulnar joints
67
Pronation and supination also require movement where?
adjacent humeroradial joint
68
Where does supination occuur?
proximal radio-ulnar joint
69
What happens during supination?
rotation of radial head with fibro-osseous ring formed by annular ligament and radial notch of ulna
70
What prohibits standard roll and slide?
tight constraint of radial head by fibro-osseous ring
71
During supination, what do the radius and carpal bones rotate?
fixed humerus and ulna
72
During pronation and supination proximal end of radius rotates where?
both proximal radio-ulnar and humeroradial joints
73
What are the arthrokinematics at humeroradial joint?
spin of fovea of radial head against rounded capitulum of humerus
74
What is the screw home mechanism of elbow?
Natural proximal migration of radius and associated ↑ joint compression of humeroradial joint
75
What can significantly disrupt functional mobility of entire distal upper extremity?
pain or limited motion at humeroradial joint
76
Pronation and supination in a weight bearing positin?
humerus and ulna rotate relative to stationary radius and hand
77
Where is the GH joint during pronation and supination with radius and hand held fixed?
partially internally rotated
78
Where are the ulna and radius positioned with radius and hand held fixed?
parallel -rod placed through epicondyle of humurus helps with orientation of this position
79
With radius and hand held firmly fixed with ground, pronation of forearm occurs by what?
external rotation of humerus and ulna
80
Rotation of humerus transferred, nearly degree for degree, to rotating ulna how?
because of tight structural fit of humero-ulnar joint
81
Moving back to full supinated position with radius hand held fixed involved what?
internal rotation of humerus and ulna relative to fixed radius and hand
82
What muscle rotates the humerus relative to fixed scapula during pronation of the forearm from weight bearing position?
infraspinatus
83
What muscle rotates the ulna relative to fixed radius during weight bearing pronation?
pronator quadratus
84
What are the arthrokinematics of the radio-ulnar joint during pronation while radius and hand are stationary?
- at proximal radio-ulnar joint annular ligament and radial notch of ulna rotate around fixed radial head
- capitulum of humerus spinning relative to fovea of fixed radius
- distal radio-ulnar joint head of ulna rotates around fixed ulnar notch of radius
85
At the proximal radio-ulnar joint, what are the arthrokinematics in weight bearing?
annular ligament and radial notch of ulna rotate around fixed radial head
86
At the distal radio-ulnar joint, what are the arthorkinematics in weight bearing?
convex ulnar head rolls and slides in opposite directions on concave ulnar notch of radius?
87
At the proximal radio-ulnar joint what are the arthrokinematics in non-weight bearing?
radial head rotates within ring formed by annular ligament and radial notch of the ulna
88
At the distal radio-ulnar joint, what are the arthrokinematics in non-weight bearing?
concavity of ulnar notch of radius rolls and slides in similar directions on convex ulna head
89
What do muscles that attach distally on the ulna do?
flex or extend the elbow, but possess no ability to pronate or supinate the forearm
90
What do muscles that attach distally on the radius do?
flex or extend the elbow, but can also pronate or supinate the forearm
91
What are the primary flexors of the elbow?
Biceps brachii, brachialis, brachioradialis and pronator teres
92
When do the biceps produce its maximal EMG signal?
when performing both flexion and supination simultaneously (spoon to mouth)
93
What is the sole function of the brachialis?
flex the elbow
94
Which muscle of the elbow generates the greatest of any muscle crossing elbow?
brachialis
95
What muscle is the longest of all elbow muscles?
brachioradialis
96
The brachioradialis causes what actions?
full elbow flexion and rotation of the forearm
97
The pronator teres has only what percentage of physiological cross sectional area of the brachialis?
50%
98
What are the primary extensors of the elbow?
triceps, anconeus
99
What allows the long head of the triceps to extend and adduct the shoulder?
attachment on the infraglenoid tubercle
100
What movement does the anconeus allow?
longitundinal and medial-lateral stability across humero-ulnar joint
101
What shoulder motion occurs with pronation?
internal rotation
102
What shoulder motion occurs with supination?
external rotation
103
How many degrees does supination alone allow?
180 degrees
104
How many degrees does pronation alone allow?
170 degrees
105
Rotation at the shoulder in addition to pronation/supination allows for how much rotation
360 degrees
106
What are the primary supinator muscles?
supinator
| biceps
107
What are the secondary muscles of supination?
extensor pollicis longus, and extensor indicis
| brachioradialis (from pronated position)
108
What are the primary pronator muscles?
pronator teres and pronator quadratus
109
What are the secondary pronators?
flexor carpi radialis,
palmaris longus
brachioradialis (from supinated position)
