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Winter 2023 - Essential Biomechanics and Kinesiology > Elbow/Forearm - WK6 ( Ch6 and 7) > Flashcards

Elbow/Forearm - WK6 ( Ch6 and 7) Flashcards

1
Q

What is the normal carrying angle for the elbow ?

A

13 degrees plus or minus 6 degrees of lateral deviation

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2
Q

What constitutes cubitus valgus ?

A

20-25 degrees of lateral deviation

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3
Q

What constitutes cubitus varus ?

A

5 degrees of medial deviation

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4
Q

Why does the normal carrying angle disappear with full elbow flexion ?

A

due to positioning of olecranon process on trochlea

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5
Q

What is the lowest intra-capsular pressure at the elbow and what is its importance ?

A

80 degrees of flexion; most comfortable for elbow discomfort

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6
Q

List all the ligaments of the elbow and their respective jobs.

A

MCL ( anterior fibers ): resists valgus, extension and flexion
MCL ( posterior fibers): resists valgus, and flexion
RCL or LCL: resists varus forces
LUCL: resists varus forces, ER of elbow complex, flexion
Annular: distraction of the radius

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7
Q

What is the functional arc of elbow flexion ?

A

30-130 degrees; despite normal AROM being -5-145 degrees.

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8
Q

Describe the arthrokinematics of: humeroulnar flexion and extension.

A

flexion: anterior roll and slide
extension: posterior roll and slide

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9
Q

Describe the arthrokinematics of: Humeroradial flexion and extension

A

flexion: anterior roll and slide
extension: posterior roll and slide

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10
Q

Describe the arthrokinematics of: PRUJ Pronation and Supination

A

Pronation: radial spin while ulna is fixed
Supination: radial spin while ulna is fixed

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11
Q

Describe the arthrokinematics of: DRUJ pronation and supination

A

pronation: palmar roll, palmar slide
supination: dorsal roll, dorsal slide

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12
Q

Describe the arthrokinematics of: PoD Pronation/Supination

A

when the radius is fixed, the ulna and humerus rotate; the ulna spins around the radius proximally, and distally; it rolls anteriorly and slide posteriorly.

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13
Q

What are some consequences of a torn interosseus membrane ?

A

-Proximal drift of radius which can cause degeneration at the humero-radial joint due to increased loading.
-bony assymetry and increased stress on elbow and wrist joint
- normally membrane allows sharing of forces at the humeroradial joint and the humeroulnar joint.

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14
Q

What are some consequences of a torn TFCC ?

A
  • Triangular fibrocartilage complex
  • marked joint multidirectional instability, resulting in pain and difficulty in motions at the forearm and wrist
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15
Q

What structures are responsible for stabilizing DRUJ ?

A

TFCC, pronator quadratus, tendon of extensor carpi ulnaris, and distal oblique fibers of interosseus membrane

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16
Q

What are the functional norms of forearm pronation and supination ?

A

50 degrees either way from neutral position

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17
Q

Explain the screw home mechanism of the elbow.

A
  • Natural proximal migration of the radius and associated increased joint compression of the humero-radial joint during active pronation.
  • compression force of joint by pronator teres
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18
Q

Give the muscles and innervations for the following motion: Elbow flexion

A

(a) brachialis, biceps brachii
(b) brachioradialis
(c) Pronator Teres

(a) Musculucutaneous N. ( C5-6)
(b) Radial N. ( C5-6)
(c) Median N. ( C6-7)

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19
Q

Give the muscles and innervations for the following motion: Elbow extension

A

Triceps Brachii, Anconeus

Radial N. ( C7-8)

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20
Q

Give the muscles and innervations for the following motion: Forearm Pronation

A

Pronator Quadratus, Pronator Teres

Median N. ( C8-T1), ( C6-7)

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21
Q

Give the muscles and innervations for the following motion: Forearm Supination

A

Biceps Brachii, Supinator

Musculocutaneous N. ( C5-6)
Radial N. ( C6)

22
Q

Give the muscles and innervations for the following motion: Wrist Flexion

A

FCR, FCU, Palmaris Longus

FDP, FDS, APL, EPB

Median and Ulnar N.

23
Q

Give the muscles and innervations for the following motion: Wrist Extension

A

ECRL+ECRB, ECU

ED, EI, EDM, EPL

Radial N.

24
Q

Give the muscles and innervations for the following motion: Wrist Radial Deviation

A

ECRL+ ECRB, FCR, APL, FPL, EPL, EPB

Radial and Median N.

25
Q

Give the muscles and innervations for the following motion: Wrist Ulnar Deviation

A

ECU, FCU, FDP and FDS, ED

Radial, Median, and Ulnar N.

26
Q

During what ROM do the following movements have the best torque potentials:
elbow; flexion, extension
Wrist: flexion, extension
Gripping

A

Elbow flexion: 85-95 degrees flexion
Elbow Extension: 80-90 degrees of flexion
Wrist Flexion: 40 degrees of flexion
Wrist Extension: 30 degrees of flexion to 70 degrees of extension
Gripping: 30-35 degrees extension at the wrist

27
Q

Which positions make the biceps active and passively insufficient ?

A

active: shoulder flexion and elbow flexion
passive: shoulder and elbow extension

28
Q

Explain the best positioning for optimal length tension relationship of the biceps and triceps.

A

Biceps: shoulder extended with elbow flexed; posterior deltoid helps modify muscle length of biceps
Triceps: shoulder flexion with elbow extended; anterior deltoid helps to neutralize shoulder extension potential of triceps

29
Q

What is the law of parsimony ?

A

the nervous system recruits fewest muscles and fibers possible for control of a given joint action.

30
Q

What is the terrible triad of the elbow ? and what is PLRI ?

A

elbow joint dislocation, radial head fracture, coronoid fracture

posterolateral rotary instability; elbow joint instability; radial head dislocates post.

31
Q

Your neighbor brings her three year old son who is complaining of lateral elbow pain after his mom picked him up by the hand when he fell to the floor. What do you suspect is wrong ?

A

Nursemaid’s elbow: pulling on his hand may have removed the radial head from the annular ligament

32
Q

How can a person with a C6 lesion transfer from supine to sit ?

A

creating a close chained allows activation of upper arm muscles to create movement of humerus on radius and ulna.

33
Q

Explain the pathomechanics of lateral epicondylalgia.

A

repetitive microtrauma involving ECRB
incomplete reparative process
symptoms; weak and painful grip
tenderness over lateral epicondyle
pain w PROM wrist flexion

34
Q

What is the OPP and CPP of the ulnohumeral joint ?

A

OPP: 70 degrees of flexion, 10 degrees of supination
CPP: extension

35
Q

What is the OPP and CPP of the radiohumeral joint ?

A

OPP: full extension and supination
CPP: 90 degrees of elbow flexion, 5 degrees of supination

36
Q

What is the OPP and CPP of the PRUJ ?

A

OPP: 70 degrees of flexion, 35 supination
CPP: 5 degrees of supination

37
Q

What is the OPP and CPP of the DRUJ ?

A

OPP: 10 degrees of supination
CPP: 5 degrees of supination

38
Q

OIIA: Biceps Brachii

A

O:Short head: tip of coracoid process of scapula
Long head: supraglenoid tubercle of scapula
I:Tuberosity of radius and fascia of forearm via bicipital aponeurosis
I:Musculocutaneous nerve (C5, C6, C7)
A:Supinates forearm and, when it is supine, flexes forearm; short head resists dislocation of shoulder

39
Q

OIIA: Brachialis

A

O: Distal half of anterior surface of humerus
I: Coronoid process and tuberosity ulna
I: Musculocutaneous nerve (C5, C6) and radial nerve (C5, C7)
A: Flexes forearm in all positions

40
Q

OIIA: Triceps

A

O: Long head: infraglenoid tubercle of scapula
Lateral head: posterior surface of humerus, superior to radial groove
Medial head: posterior surface of humerus, inferior to radial groove
I:Proximal end of olecranon of ulna and fascia of forearm
I:Radial nerve (C6, C7, C8)
A: Chief extensor of forearm; long head resists dislocation of humerus; especially important during adduction

41
Q

OIIA: Anconeus

A

O: Lateral epicondyle of humerus
I: Lateral surface of olecranon and superior part of posterior surface of ulna
I: Radial nerve (C7, C8, T1)
A: Assists triceps in extending forearm; stabilizes elbow joint; may abduct ulna during pronation

42
Q

OIIA: Brachioradialis

A

O: Proximal two thirds of lateral supra-epicondylar ridge of humerus
I: Lateral surface of distal end of radius proximal to styloid process
I: Radial nerve (C5, C6, C7)
A: Relatively weak flexion of forearm; maximal when forearm is in midpronated position

43
Q

OIIA: Pronator Teres

A

O: Ulnar Head: coronoid process, Humeral head: medial epicondyle of humerus
I: Middle of convexity of lateral surface of radius
I:Median nerve (C6, C7)
A: Pronates and flexes forearm (at elbow)

44
Q

OIIA: Pronator Quadratus

A

O: Distal quarter of anterior surface of ulna
I: Distal quarter of anterior surface of radius
I: Anterior interosseous nerve, from median nerve (C8, T1)
A: Pronates forearm; deep fibers bind radius and ulna together

45
Q

OIIA: Supinator

A

O: Lateral epicondyle of humerus; radial collateral and anular ligaments; supinator fossa; crest of ulna
I: Lateral, posterior, and anterior surfaces of proximal third of radius
I: Deep branch of radial nerve (C7, C8)
A: Supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)

46
Q

What are the AAOS norms for: Elbow Flexion and Extension

A

Flexion:150
Extension:0

47
Q

What are the AAOS norms for: Supination and Pronation of the forearm

A

Supination:80
Pronation:80

48
Q

What are the AAOS norms for: Wrist Flexion and Extension

A

Flexion: 80
Extension: 70

49
Q

What are the AAOS norms for: Wrist Radial and Ulnar Deviation

A

Radial Dev.: 20
Ulnar Dev.:30

50
Q

During proximal on distal motion, which motion occurs with shoulder external rotation?

A

pronation of the forearm

Winter 2023 - Essential Biomechanics and Kinesiology (16 decks)

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