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Biomechanics > Exam II > Flashcards

Exam II Flashcards

1
Q

what are the 3 true joints of the shoulder? what are the 2 articulations of the shoulder?

A 
True Joints
(1) GH joint
(2) AC joint
(3) SC joint
Articulations
(1) Scapulothoracic
(2) Suprahumeral articulation
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2
Q

the head of the humerus is much larger than the glenoid fossa, as a result what is the shoulder prone to?

A

instability; dislocations

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3
Q

what covers the glenoid cavity?

A

the labrum

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4
Q

what is the purpose of the labrum? (2)

A

(1) deepens the cavity

2) creates a negative pressure inside the cavity (like a suction cup

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5
Q

what angle is the humeral head at in the glenoid cavity?

A

30 degrees of retroversion; angled between frontal and sagittal planes

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6
Q

what sports might you see an increased amount of retroversion?

A

overhead throwing sports, such as baseball

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7
Q

what is the closed pack position of the GH joint?

A

90 degrees abduction, full ER

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8
Q

what is the open pack position of the GH joint?

A

40-50 degrees of abduction, 30 degrees of horizontal adduction

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9
Q

how does an increased retroversion of the shoulder affect ROM?

A

increased retroversion leads to increased ER at the GH joint; also leads to decreased IR (GIRD)

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10
Q

what are the passive mechanisms that provide stability to the GH joint? (4)

A

(1) capsule, ligaments, labrum, and tendons
(2) posture
(3) negative intracapsular pressure
(4) acromion (prevent superior subluxation)

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11
Q

how does poor posture contribute to GH instability?

A

forward shoulder posture can cause downward rotation of the GH joint causing ligament laxity; can also cause the humerus to travel superiorly

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12
Q

what attaches to the glenoid labrum?

A

the biceps tendon; about 50% of the tendon fibers attach to labrum

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13
Q

why are baseball players more prone to SLAP tears?

A

the biceps tendon works to decelerate the arm in throwing motions, increasing risk of labral tears

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14
Q

what is one reason a SLAP tear causes decreased stability of the GH joint?

A

tearing the labrum causes a decrease of negative pressure in the joint

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15
Q

what is a bankart lesion? what is typically the cause?

A

tear of anterior-inferior labrum (often with fracture of glenoid rim); usually caused by anterior dislocation or fracture

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16
Q

what are the movements that accompany GH abduction?

A

(1) inferior glide

(2) external rotation

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17
Q

what are the movements that accompany GH adduction?

A

(1) superior glide

(2) internal rotation

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18
Q

what are the movements that accompany GH external rotation?

A

(1) anterior glide

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19
Q

what are the movements that accompany GH internal rotation?

A

(1) posterior glide

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20
Q

what are the movements that accompany GH flexion?

A

(1) external rotation

(2) inferior glide

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21
Q

what are the movements that accompany GH extension?

A

(1) internal rotation

(2) inferior glide

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22
Q

with elevation of the humerus, which position puts the least amount of stress on the joint?

A

scaption (not pure flexion or pure abduction)

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23
Q

other than it’s muscle actions, what is the main role of the supraspinatus?

A

prevents superior translation of the humeral head

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24
Q

what can happen if the supraspinatus is torn or injured?

A

it can’t effectively prevent superior translation of the humerus, which can result in subacromial impingement

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25
Q

what is the normal space between the humerus and acromion in a resting position?

A

10-12 mm

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26
Q

what is the GH joint designed for?

A

mobility; NOT stability

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27
Q

how much retroversion do baseball players tend to have?

A

45 degrees

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28
Q

during shoulder elevation, what range is subacromial space the smallest?

A

60-80 degrees

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29
Q

what type of joint is the SC joint?

A

a saddle joint

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30
Q

how would you describe the surfaces of the SC joint?

A

Frontal Plane
-A convex clavicle moves on a concave sternum
Sagittal Plane
-A concave clavicle moves on a convex sternum

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31
Q

why is arthritis uncommon at the SC joint?

A

it has a fibrocartilage disc between the clavicle and sternum that absorbs shock

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32
Q

when protraction/retraction occurs, which way are the roll and glides at the SC joint?

A

the roll and glide occur in the same direction (sagittal plane movement)

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33
Q

when elevation/depression occurs, what way does the SC joint glide?

A

Elevation (frontal plane)
-inferior glide
Depression (frontal plane)
-superior glide

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34
Q

when raising the arm overhead, which way does the clavicle rotate?

A

superior aspect of the clavicle rotates posteriorly 20-35 degrees; clavicle rotates back when arm is returned to side

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35
Q

which joint contributes more to scapular motion, the AC joint or SC joint?

A

SC joint

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36
Q

what injuries are common at the AC joint? what sports are these injuries most likely to occur?

A

dislocations and instability are most common; contact sports (ex. football or rugby)

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37
Q

can damage to the SC joint be fixed by exercise?

A

no because to muscles hold the SC joint in place

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38
Q

do passive or active structures most contribute to the stability of the AC joint?

A

passive; mainly ligaments, but the deltoids and upper traps play a small role

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39
Q

what is the most important ligament to the stability of the AC joint? why?

A

coracoclavicular ligament; stronger and absorbs more energy than other ligaments of the shoulder

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40
Q

what is the main function of the coracoclavicular ligament?

A

prevent posterior rotation and subluxation of the clavicle

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41
Q

what is the difference between a joint and an articulation?

A

a joint has cartilage between bones, while an articulation doesn’t (ex. ST joint is an articulation)

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42
Q

where does the ST joint articulate?

A

between the scapula and ribcage

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43
Q

how many degrees of freedom does the ST joint have? what are they?

A

3 DOF

(1) anterior/posterior tilt
(2) IR / ER
(3) upward/downward rotation

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44
Q

what happens at the SC and AC joints during ST joint elevation? (2)

A

(1) Elevation at the SC joint
(2) Downward rotation at the AC joint

Test Question

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45
Q

what happens at the SC and AC joints during ST joint protraction? (2)

A

(1) protraction of the SC and AC joints

(2) internal rotation of the AC joint

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46
Q

what happens at the SC and AC joints during ST joint upward rotation? (2)

A

(1) elevation of the SC joint

(2) upward rotation of the AC joint

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47
Q

what are the main functions of the ST joint? (3)

A

(1) position the glenoid (upwardly rotated) so the shoulder functions properly
(2) maintain the length/tension relationship between delt and supraspinatus
(3) preserve subacromial space

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48
Q

what joints of the shoulder don’t follow the concave/convex rule?

A

AC joint and ST joint

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49
Q

how many degrees of freedom does the SC joint have? what are they?

A

3 DOF

(1) protraction / retraction
(2) elevation / depression
(3) anterior / posterior rotation (less discussed, not a ‘major’ movement)

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50
Q

what is responsible for ST joint mobility?

A

ST joint movement is the result of movement at the AC and SC joints

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51
Q

what is scapulohumeral (SH) rhythm?

A

the coordinated motion of the humerus and scapula during elevation (flexion, scaption, abduction)

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52
Q

what is the ratio of humeral motion to scapular motion? (1st Kinematic Principle of Abduction)

A

2:1 (120 degrees of GH abduction to 60 degrees of scapular upward rotation)

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53
Q

what creates the 60 degrees of scapular upward rotation? (2nd Kinematic Principle of Abduction)

A

(1) elevation of the SC joint
(20-35 degrees from posterior rotation of the SC joint)
(2) upward rotation of the AC joint (30 degrees)

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54
Q

how much does the clavicle retract during full abduction?

3rd Kinematic Principle of Abduction

A

15-20 degrees

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55
Q

during full shoulder abduction what occurs with the tilt and rotation of the scapula? (4th Kinematic Principle of Abduction)

A

(1) posteriorly tilts (20 degrees)

2) externally rotates (0-5 degrees

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56
Q

how is the clavicle rotated posteriorly during full abduction? (5th Kinematic Principle of Abduction)

A

(1) as the serratus anterior upwardly rotates the scapula, which pulls the coracoclavicular ligament tight
(2) this causes the clavicle to rotate posteriorly around it’s own axis
(3) this causes the AC joint to allow full upward rotation

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57
Q

when an arm is fully abducted or flexed to 180 degrees, how much ER is observed at the GH joint? why does this ER occur? (6th Kinematic Principle of Abduction)

A

40 degrees; allows the greater tubercle to pass posterior to the acromion to avoid impingement of the greater tubercle in the subacromial space

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58
Q

what are 2 ways motion in the scapular plane is more beneficial than movement in the frontal or sagittal plane?

A

(1) prevents subacromial impingement

(2) reduces stress on the labrum

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59
Q

what population of patients would motion in the scapular plane be recommenced for?

A

(1) after capsular shift surgeries
(2) after labral repairs
(3) after shoulder surgery

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60
Q

what is the neutral position of the shoulder?

A

30 degrees retroversion

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61
Q

where do most of the proximal stabilizers and distal mobilizers insert?

A

(1) proximal stabilizers insert on the scapula and clavicle

(2) distal mobilizers insert on the humerus or forearm

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62
Q

what do the proximal stabilizers and distal mobilizers act on?

A

(1) proximal stabilizers act on the AC, SC, and ST joints

(2) distal mobilizers act on the GH joint

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63
Q

what muscles may act as both proximal stabilizers and distal mobilizers? (2)

A

(1) serratus anterior

(2) traps

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64
Q

what are the proximal stabilizers that elevate the ST joint? (3)

A

(1) upper traps
(2) levator scapulae
(3) rhomboids

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65
Q

what are the proximal stabilizers that depress the ST joint? (4)

A

(1) lower traps
(2) lats
(3) pec minor
(4) subclavius

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66
Q

what muscles are involved with raising the body from a chair to another surface?

A

the depressors (think what muscles would work if your triceps didn’t function)

Test Question

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67
Q

what are the proximal stabilizers that protract the ST joint? (1)

A

serratus anterior

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68
Q

what are the proximal stabilizers that retract the ST joint? (3)

A

(1) middle traps
(2) rhomboids
(3) lower traps
- the rhomboids and lower traps work synergistically to cause retraction; they have opposing vectors

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69
Q

what are the proximal stabilizers that upwardly rotate the ST joint? (3)

A

(1) serratus anterior
(2) upper traps
(3) lower traps
- all muscles working synergistically

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70
Q

what are the proximal stabilizers that downwardly rotate the ST joint? (2)

A

(1) rhomboids

(2) lats

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71
Q

what are the distal mobilizers that abduct the GH joint? (2)

A

(1) deltoid (anterior and middle)

(2) supraspinatus

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72
Q

what are the distal mobilizers that adduct the GH joint? (4)

A

(1) infraspinatus
(2) teres major
(3) deltoid (posterior)
(4) triceps (long head)

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73
Q

what are the distal mobilizers that elevate the GH joint? (6)

A

(1) deltoid (anterior and medial)
(2) coracobrachialis
(3) biceps
(4) all 4 rotator cuff muscles
- Both Proximal Stab / Distal Mob
(1) serratus anterior
(2) traps

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74
Q

what distal mobilizers assist with upward rotation of the ST joint?

A

abductors

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75
Q

what distal mobilizers assist with downward rotation of the ST joint?

A

adductors

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76
Q

what is the rotator cuff’s function during arm elevation?

A

(1) tighten capsule to improve stability of GH joint
(2) compress humeral head against fossa
(3) controls active arthrokinematics of the GH joint

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77
Q

when the arm is elevated, it also externally rotates. why is this a more unstable position?

A

because it moves the RC tendons to a more lateral and posterior position, leaving the anterior shoulder more unstable (think about cocking back to throw a baseball)

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78
Q

below 90 degrees of elevation, what is mainly responsible to stability of the GH joint? what about above 90 degrees?

A

(1) below 90 degrees, the rotator cuff is mainly responsible for stabilizing the GH joint
(2) above 90 degrees, the capsule and ligaments are mainly responsible for stabilizing the GH joint (with assistance from RC)

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79
Q

what is an obligate translation?

A

when capsule and ligaments are tight in one direction and cause translation in the opposite direction (ex. tight posterior capsule causes humeral head to translate anteriorly during IR)

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80
Q

when a capsule is tight that causes obligate translations, what can occur?

A

obligate translations can cause laxity and instability of the capsule in the opposite direction of capsular tightness; can also cause impingement

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81
Q

what are 3 functions of the supraspinatus with regard to controlling arthrokinematic movement?

A

(1) drives the superior roll of the humeral head
(2) compresses the humeral head against the fossa
(3) resists excessive superior translation of the humerus

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82
Q

what is the function of the infraspinatus, teres minor, and subscap with regard to controlling arthrokinematic movement?

A

exert a depressive force on the humeral head

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83
Q

weakness of what muscles may lead to abnormal arm elevation?

A

(1) traps

(2) RC muscles

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84
Q

the adductors and extensors often act in combination, what muscles adduct and extend the arm?

A

(1) lats
(2) teres major
(3) deltoid (posterior)
(4) triceps (long head)
(5) pec major (sternal head)

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85
Q

what are the strongest muscles of the shoulder?

A

adductors and extensors (should make sense if you think of muscle bulk)

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86
Q

what muscles are often utilized by paraplegic patients with bilateral crutches?

A

adductors and extensors because they’re strong muscles

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87
Q

what are the distal mobilizers that internally rotate the GH joint? (5)

A

(1) subscap
(2) pec major
(3) lats
(4) teres major
(5) anterior delt

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88
Q

are internal rotators or external rotators of the shoulder stronger? why?

A

internal rotators are stronger; they have larger cross sectional areas

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89
Q

what are the distal mobilizers that externally rotate the GH joint? (3)

A

(1) infraspinatus
(2) teres minor
(3) posterior deltoid
- the supraspinatus acts as an ER when shoulder is flexed

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90
Q

where do the external rotators all attach?

A

between the scapula and humerus

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91
Q

if the scapular stabalizers are weak, what happens to the scapula during ER?

A

the scapula will wing because the external rotators are stronger than the scapular stabilizers, thus they pull the scapula off the rib cage

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92
Q

why doesn’t winging happen with internal rotation?

A

because internal rotators attach to the scapula and the trunk, so they act as scapular stabilizers

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93
Q

why do high velocity throwing sports, such as baseball, lead to tears of the infraspinatus and teres minor?

A

those muscles are required to eccentrically contract at high velocities (eccentric deceleration at the end of a throw)

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94
Q

what are the weakest muscles of the shoulder?

A

(1) external rotators (weakest)

(2) internal rotators

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95
Q

what are the two types of scapular dyskinesis?

A

(1) dysrhythmia: excessive elevation or protraction, non-smooth motion with elevation
(2) winging: medial border of the scapula are posteriorly displaced away from the thorax

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96
Q

what is the most common cause of scapular dyskinesia?

A

dysfunction of the proximal stabilizers of the shoulder

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97
Q

what are the 3 types of GH instability?

A

(1) acquired: repetitive high velocity motions with extreme ER and ABD; internal impingement
(2) atraumatic: uni or multidirectional; responds well to PT
(3) post-traumatic: (fall or collision; often injures cuff, anterior-inferior rim of the glenoid and labrum

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98
Q

what is the most common disorder of the shoulder?

A

subacromial impingement

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99
Q

what tissues are most commonly affected with subacromial impingement?

A

supraspinatus, biceps long head, superior capsule, subacromial bursa

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100
Q

what is the mechanical disadvantage of the supraspinatus?

A

1:20

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101
Q

what are the two types of osteokinematic motion?

A

spin and swing

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102
Q

what is the difference between spin and swing? which is more common?

A

spin occurs in one plane and swing occurs in multiple planes; swing occurs in 99% of motion (most motion occurs in multiple planes); spin is linear and swing is angular motion

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103
Q

what are some examples of when spin occurs?

A

during brief moments of shoulder flexion, hip flexion and pronation at the proximal radio-ulnar joint

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104
Q

what is the only joint of the spine that follows the concave/convex rule?

A

the atlanto-occipital joint

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105
Q

what is the difference between open and closed kinematic chain?

A

close chain: distal end of the kinetic chain is fixed (ex. squat, pull-ups)
open chain: distal end of the chain is free (ex. knee extensions, biceps curls)

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106
Q

what type of exercises are more functional and more optimal for strengthening the lower extremity?

A

closed-chain

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107
Q

what are the differences between the closed and open packed positions?

A

closed pack: excellent congruency (stress evenly distributed), least joint space, capsule tight
loose pack: poor congruency, joint space maximized, loose capsule

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108
Q

what position is a joint most stable, open or closed pack?

A

closed pack

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109
Q

what is the purpose of the elbow angle?

A

it’s a carrying angle, so it allows us to carry things without bumping into LE

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110
Q

what is the average elbow or carrying angle?

A

15 degrees

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111
Q

how does elbow angle vary between gender, age, and height?

A

(1) females have wider angles due to having wider hips
(2) the angle gets larger as you age
(3) larger in shorter people (ASK LADIRA)

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112
Q

what is considered excessive valgus and varus at the elbow?

A

excessive valgus: >30 degrees

varus: <5 degrees

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113
Q

what type of dysfunction can an increased elbow angle lead to?

A

dysfunction of the ulnar nerve (due to excessive friction)

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114
Q

how would the humeroradial and humeroulnar joints be described from a stability standpoint?

A

both are very stable joints; seldomly dislocates or subluxes

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115
Q

what are more common injuries at the humeroradial and humeroulnar joints, ligament tears or fractures?

A

fractures

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116
Q

what are the joint surfaces of the bones that make up the elbow joint, as far as concavity and convexity?

A

(1) humerus: convex
(2) radius: concave
(3) ulna: concave

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117
Q

what are the open pack (resting position) and closed pack for the humeroradial joint?

A

open pack: extension and forearm supination

closed pack: 90 degrees of flexion, 5 degrees of supination

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118
Q

what are the open pack (resting position) and closed pack for the humeroulnar joint?

A

open pack: 70 degrees of flexion, 10 degrees of supination

closed pack: full extension and supination

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119
Q

what direction are the roll and glide during elbow flexion? elbow extension?

A

flexion: roll and glide are both anterior
extension: roll and glide are both posterior

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120
Q

why aren’t glides used clinically for mobilization of the humeroulnar joint?

A

the ulna will jam against the humerus, so a bony block typically prevents effective glides as manual therapy techniques

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121
Q

what manual therapy technique can be effective for improving flexion and extension at the elbow joint?

A

distraction

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122
Q

when the elbow extends, what accessory movement occurs?

A

the ulna abducts when the arm is extended

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123
Q

when the elbow flexes, what accessory movement occurs?

A

the ulna adducts when the arm is flexed

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124
Q

what prevents hyperextension at the elbow?

A

the olecranon entering the fossa blocks the motion to prevent hyperextension

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125
Q

what prevents excessive flexion at the elbow?

A

ulnar coronoid process enters it’s fossa preventing excessive flexion (or large biceps muscle stops it early)

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126
Q

when the arm is fully extended, does the radius contact the humerus?

A

no

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127
Q

how does the contact between the trochlea and ulna differ between open chain and closed chain movements?

A

(1) open chain: no contact between the two bones between 30-120 degrees
(2) closed chain: constant contact

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128
Q

when does the radius come in contact with the humerus?

A

at end range elbow flexion

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129
Q

what are the two dynamic stabilizers of the humeroulnar joint?

A

(1) flexor carpi ulnaris

(2) pronator teres

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130
Q

what does the humeroradial rely on for stability?

A

its ligaments and capsule; bone structure doesn’t help as much at this joint as it does at the humeroulnar joint

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131
Q

where is the capsule of the elbow weakest? where is it strongest?

A

weakest: anterior and posterior (loose in these directions)
strongest: medial and lateral (reinforced by collateral ligaments)

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132
Q

how many bands make up the MCL? what are the names of the bands?

A

(1) anterior fibers
(2) posterior fibers
(3) transverse fibers

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133
Q

what ligaments make up the lateral collateral ligament complex?

A

(1) radial collateral ligament
(2) lateral ulnar collateral ligament (LUCL)
(3) annular ligament

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134
Q

what is the function of the anterior fibers of the MCL?

A

prevent valgus throughout flexion and extension

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135
Q

what is the function of the posterior fibers of the MCL?

A

prevent valgus in extreme (full) flexion of the elbow

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136
Q

what causes the terrible triad injury to occur at the elbow? what are the 3 structures that are damaged?

A

(1) extreme compression, hyperextension and valgus force

(2) joint dislocation (extensive ligament damage), fracture of radial head, and fracture of coronoid process

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137
Q

what type of injury most commonly causes valgus stress?

A

falling with the arm extended

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138
Q

what are the functions of the LCL complex at the elbow?

A

(1) stabilizes against varus torque
(2) stabilizes against simultaneous varus and supination torque
(3) resists longitudinal distraction
(4) fixates radial head for rotation
(5) prevents posterior lateral instability
(6) prevents humeroulnar subluxation

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139
Q

when is the LUCL most taut?

A

at full elbow flexion

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140
Q

what is the function of the LUCL?

A

(1) prevents excessive varus and valgus through flexion and extension
(2) prevents excessive external rotation of proximal forearm relative to humerus
(3) prevents radial head from dislocating

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141
Q

what is the function of the annular ligament of the elbow?

A

prevents the radial head from distracting

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142
Q

what causes a posterolateral rotatory instability (PLRI) injury of the elbow?

A

varus, supination, and external rotation of the forearm, with the shoulder internally rotated

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143
Q

what is the function of the radial collateral ligament?

A

prevent excessive varus of the elbow

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144
Q

what are the functions of the MCL?

A

(1) limit extension at end range
(2) guide motion through flexion
(3) resist longitudinal distraction

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145
Q

how much elbow flexion and extension is required for most people to complete ADLs?

A

30 - 130 degrees of motion
30 degrees extension
130 degrees of flexion

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146
Q

what are the two most important ligaments of the elbow to provide stability?

A

(1) anterior fibers of MCL

(2) LUCL

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147
Q

what type of loads are most damaging to the elbow?

A

bending and torsion

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148
Q

how many degrees of freedom are available at the radioulnar joint?

A

1 DOF; pronation and supination, radius rotates around a fixed ulna

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149
Q

how many degrees of motion occur at the radioulnar joint?

A

180 degrees; 90 from pronation / 90 from supination

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150
Q

what joint might contribute to the last 15-20 degrees of supination?

A

the radiocarpal joint

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151
Q

what are the closed pack and open pack positions of the proximal radioulnar joint?

A

(1) closed pack: 5 degrees of supination

(2) open pack: 70 degrees flexion, 35 degrees supination

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152
Q

what are the closed pack and open pack positions of the distal radioulnar joint?

A

(1) closed pack: 5 degrees of supination

(2) open pack: 10 degrees supination

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153
Q

what are the 2 main functions of the interosseous membrane between the radius and ulna?

A

(1) provide stability to both the proximal and distal radioulnar joints (prevents bones from spreading apart)
(2) helps transmit the load from the radius to the ulna and evenly distribute force to humerus

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154
Q

in a closed kinematic chain, how much of the load does the radius (radiocarpal joint) bear (like in a push-up)?

A

80%

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155
Q

what structure helps distribute force coming up the arm so that there is equal force on both sides of the humerus?

A

interosseous membrane

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156
Q

what are the three parts of the interosseous membrane?

A

(1) oblique cord
(2) central band
(3) distal oblique fibers

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157
Q

what structures help transmit open kinematic chain pulling forces at the elbow? (4)

A

(1) oblique cord
(2) annular ligament
(3) brachioradialis
(4) MCL (when strong external forces are carried)

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158
Q

what is the concave/convex rule at the proximal radioulnar joint in an OPEN CHAIN?

A

roll and glide are in OPPOSITE directions; ulna is fixed

proximal ulna is concave, convex radius moves on ulna

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159
Q

what is the concave/convex rule at the distal radioulnar joint in an OPEN CHAIN?

A

roll and glide are in SAME directions; ulna is fixed

distal ulna is convex, concave radius moves on ulna

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160
Q

what other motions occur when the elbow is flexed in an open chain?

A

(1) forearm supination

(2) ER of the shoulder

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161
Q

what other motions occur when the elbow is extended in an open chain?

A

(1) forearm pronation

(2) IR of the shoulder

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162
Q

in a closed chain (with elbow near full extension), what happens to the forearm when the shoulder is externally rotated?

A

the forearm pronates

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163
Q

in a closed chain (with elbow near full extension), what happens to the forearm when the shoulder is internally rotated?

A

the forearm supinates; helps lock the elbow in full extension for stability

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164
Q

what is the concave/convex rule at the proximal radioulnar joint in a CLOSED CHAIN?

A

roll and glide are in the SAME direction; radius is fixed

proximal ulna is concave and moves on convex radius

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165
Q

what is the concave/convex rule at the distal radioulnar joint in a CLOSED CHAIN?

A

roll and glide are in the OPPOSITE direction; radius is fixed
(distal ulna is convex and moves on concave radius)

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166
Q

what structures provide passive stability to the proximal radioulnar joint? (4)

A
  • 2 structures hold radial head
    (1) annular ligament
    (2) radial notch of ulna
  • Also contribute to stability
    (1) interosseous membrane
    (2) quadrate ligament
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167
Q

what is the traffic light injury?

A

when parents pull their child up by their hands and the radial head subluxes from the annular ligament

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168
Q

what is the most important structure and primary stabilizer of the distal radioulnar joint?

A

TFCC (triangular fibrocartilage complex)

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169
Q

what can damage to the TFCC result in?

A

multi-directional joint instability

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170
Q

what structures provide stability to the distal radioulnar joint?

A

(1) TFCC
(2) interosseous membrane (controls pronation and supination)
(3) pronator quadratus
(4) extensor carpi radialis

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171
Q

what 2 ligaments help maintain the radius against the ulna during pronation and supination?

A

(1) dorsal radioulnar ligament

(2) palmar radioulnar ligament

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172
Q

what are 2 common mechanisms of injury to the TFCC?

A

(1) fall on supinated, outstretched wrist

2) chronic repetitive rotational loading (ex. tennis players

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173
Q

how much pronation and supination is required for most people to complete ADLs?

A

50 degrees of pronation

50 degrees of supination

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174
Q

what joint is more mobile and less stable, the PRUJ or DRUJ?

A

DRUJ

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175
Q

what are the primary elbow flexors? (4)

A

(1) biceps brachii
(2) brachialis
(3) brachioradialis
(4) pronator teres

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176
Q

what muscles attach to the radius and have the ability to pronate/supinate? (3)

A

(1) biceps brachii
(2) brachioradialis
(3) pronator teres

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177
Q

when is the biceps brachii most active? least active?

A

most active with combined flexion and supination; least active with combined flexion and pronation

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178
Q

what is the strongest muscle of the elbow flexors, which is also known as the work horse of the flexors?

A

brachialis (largest cross section)

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179
Q

what is the weakest elbow flexor?

A

pronator teres (smallest cross section)

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180
Q

in what position is the shoulder in optimal position to shorten and produce force?

A

with the shoulder in extension with the elbow flexed

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181
Q

what head of the biceps has a larger internal moment arm for flexion? what does this mean?

A

the short head of the biceps has a greater internal moment arm; it can produce 15% greater flexion torque than the long head

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182
Q

what muscle of the elbow is the longest and has the largest moment arm? what is this muscle designed for?

A

brachioradialis; designed for speed

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183
Q

what muscle has the largest cross section of the flexors? what is this muscle designed for?

A

brachialis; power (heavy lifting)

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184
Q

which elbow flexor what a hybrid function of both speed and power?

A

biceps brachii

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185
Q

at what range can the elbow flexors produce the most torque (strongest)?

A

85-100 degrees of flexion

186
Q

at what range do the elbow flexors produce the least amount of torque (weakest)?

A

near full extension (0 degrees)

near full flexion (125+ degrees)

187
Q

what are the strongest muscles of the elbow? what are the weakest?

A

Strongest to Weakest

1) flexors (strongest
(2) extension
(3) supination
(4) pronation (weakest)

188
Q

how much stronger are the flexors than the extensors?

A

70%

189
Q

why is flexor strength 20-25% stronger in supination than in pronation?

A

due to the role of the biceps when supinated

190
Q

what are the primary extensors of the elbow? (2)

A

(1) anconeus

(2) triceps

191
Q

in minimum effort tasks, what initiates and controls elbow extension?

A

anconeus

192
Q

what is the order in which elbow extensors are activated?

A

(1) anconeus (low effort)
(2) medial head of triceps (low effort)
(3) lateral head (moderate high effort)
(4) long head (high effort)

193
Q

which elbow extensors works as a “reserve” and only kicks in during very high demand activities?

A

long head of triceps

194
Q

what is the law of parsimony? how does this law benefit movement?

A

hierarchical activation of muscles based on required torque; helps with energy expenditure

195
Q

what are 4 principles that the law of parsimony follows?

A

(1) smaller motor unit / smaller fibers before large ones
(2) red before white
(3) smaller cross section before larger
(4) uni-articular before bi-articular muscles

196
Q

what is the long head of the triceps designed for?

A

speed and strength; long fibers, large volume

197
Q

what are the lateral and medial heads of the triceps designed for?

A

together designed for strength; shorter fibers, medium cross section

198
Q

what percentage of elbow torque is the anconeus responsible for?

A

15%

199
Q

at what range can the elbow extensors produce the most torque (strongest)?

A

20-30 degrees of elbow flexion

200
Q

when performing a pushing motion, the triceps and anterior deltoid act to do what?

A

the elbow extends as the anterior delt flexes, this causes an isometric co-activation which provide stability to the shoulder joint

201
Q

if a person has the inability to use their triceps, how is that person able to supinate the forearm?

A

by internally rotating their shoulder

202
Q

what are the primary supinators of the forearm? (2)

A

(1) supinator

(2) biceps brachii

203
Q

which supinator muscle is most active?

A

supinator (it’s mono-articular); the biceps is recruited during higher power supination activities

204
Q

at what angle does the biceps function best as a supinator?

A

near 90 degrees of elbow flexion

205
Q

what synergistic action occurs with vigorous supination?

A

the triceps muscle activates to prevent elbow flexion (while the biceps is supinating)

206
Q

what are the primary pronators of the forearm? what are the secondary pronators?

A 
Primary
(1) pronator teres
(2) pronator quadratus
Secondary
(1) FCR
(2) palmaris longus
207
Q

what pronator is the most active?

A

pronator quadratus (mono-articular)

208
Q

what pronator is only active during high power pronation activities?

A

pronator teres (bi-articular)

209
Q

what nerve runs through the two heads of the pronator teres and can become compressed?

A

median nerve

210
Q

what muscle acts as a dynamic stabilizer of the distal radioulnar joint?

A

pronator quadratus

211
Q

what muscle acts as a dynamic stabilizer of the proximal radioulnar joint?

A

pronator teres

212
Q

what are the most common mechanisms of injury for MCL tears?

A

(1) trauma
(2) overuse (common in baseball players)
caused by valgus / ER rotational stress

213
Q

what band of the MCL is most commonly injured?

A

anterior band

214
Q

what are some complications that can arise from MCL tears?

A

(1) avascular necrosis of the capitulum
(2) displaced medial epicondyle
(3) damage to epiphyseal plate in children/teens

215
Q

what is the name of the surgery to repair the MCL of the elbow?

A

Tommy John surgery

216
Q

what is the most common elbow injury? what causes it?

A

lateral epicondylitis; repetitive wrist extension and supination

217
Q

what extensor muscle is most commonly affected by lateral epicondylitis?

A

ECRB

218
Q

how does a tennis elbow strap work?

A

(1) decreases stress applied to ECRB muscle

(2) reduces muscle activation / contraction of extensors

219
Q

MCL laxity can cause what type of injury?

A

capitulum compression injury

220
Q

what is the ‘most important’ joint of the wrist? why?

A

radiocarpal joint; most motion of the wrist occurs at this joint (angular movements of the sagittal and frontal planes)

221
Q

what carpal bones does the radius articulate with?

A

scaphoid and lunate

222
Q

what does the TFCC do from a weight distribution standpoint?

A

helps transfer weight from radius to the wrist

223
Q

when the wrist is compressed (think closed chain) what percentage of the compressive load is transferred by the radiocarpal joint? what percentage is transferred by the TFCC?

A

(1) radiocarpal joint: 80%

(2) TFCC: 20%

224
Q

of the compressive forces from the radius, what percentage of load is transferred to the scaphoid? what about the lunate?

A

(1) scaphoid: 60%

(2) lunate: 40%

225
Q

at the radiocarpal joint, how would you describe the articular surfaces of the radius, scaphoid, and lunate from concave/convex perspective?

A

(1) radius is concave in both frontal and sagittal planes

(2) scaphoid and lunate are both convex in both frontal and sagittal planes

226
Q

which direction do the first row of carpals glide when radial deviation occurs?

A

medially (towards the ulna)

227
Q

how many DOF does the midcarpal joint have?

A

2; flexion/extension and radial/ulnar deviation

228
Q

what bones make up the medial compartment of the midcarpal joint?

A

CONVEX capitate & hamate
which fit into
CONCAVE scaphoid, lunate and triquertrum

229
Q

what bones make up the lateral compartment of the midcarpal joint?

A

CONVEX scaphoid
which fits into
CONCAVE trapezium / trapezoid

230
Q

which compartment of the midcarpal joint has more motion?

A

medial compartment

231
Q

what range (in degrees) of ulnar variance is considered normal?

A

15-25 degrees

232
Q

what happens with positive ulnar variance? what pathology is this associated with?

A

(1) the ulna is longer than radius

(2) TFCC injury

233
Q

what happens with negative ulnar variance? what pathology is this associated with?

A

(1) the ulna is shorter than radius

2) Kienbock’s disease (damage to lunate

234
Q

what is the difference between intrinsic and extrinsic ligaments of the wrist?

A

(1) intrinsic: only join carpal bones

(2) extrinsic: joint forearm with carpal bones or fingers

235
Q

which ligaments are stronger, palmar ligaments or dorsal ligaments?

A

palmar ligaments (support weight of body, like in a push-up); the dorsal ones are thinner and weaker

236
Q

what is the purpose of the V shape that the ligaments of the wrist create?

A

help passively guide radial and ulnar deviation

237
Q

what is difference between the TFC and TFCC?

A

(1) TFC: only the ulnar disc

(2) TFCC: the entire complex, including the disc or TFC

238
Q

what is the axis for radial and ulnar deviation?

A

capitate

239
Q

what structures make up the TFCC? (4)

A

(1) ulnar collateral ligament
(2) palmar ulnocarpal ligament
(3) palmar radioulnar joint ligament
(4) TFC (disc)

240
Q

what movement occurs with wrist extension?

A

radial deviation

241
Q

what movement occurs with wrist flexion?

A

ulnar deviation

242
Q

when the wrist if fully flexed and moves into full extension, where does most of the motion occur throughout the motion?

A

(1) fully flexed to neutral; motion occurs between 1st and 2nd row of carpals
(2) from neutral to 30 deg extention; motion occurs between scaphoid and triquertrum / lunate
(3) from 30 deg extension to full extension; motion occurs between carpals and radius / TFCC

243
Q

which direction does the first row of carpals glide during wrist flexion?

A

dorsally (posterior)

244
Q

which direction does the first row of carpals glide during wrist extension?

A

palmarly (anterior)

245
Q

which direction does the second row of carpals glide during wrist flexion?

A

dorsally (posterior)

246
Q

which direction does the second row of carpals glide during wrist extension?

A

palmarly (anterior)

247
Q

when the wrist is compressed which way does the first row of carpals glide? what structure can excessive wrist compression damage?

A

they glide medially (towards ulna); the TFCC

248
Q

where do the primary and secondary muscles of the wrist attach?

A

(1) primary: muscles attach to carpal bones

(2) secondary: cross carpal bones and attach to fingers and thumb

249
Q

what are the primary (3) and secondary (4) wrist extensors?

A 
primary
(1) ECRL
(2) ECRB
(3) ECU
secondary
(1) ED
(2) extensor indicis
(3) extensor digiti minimi
(4) EPL
250
Q

muscles further from the axis have a better ability to do what?

A

produce torque

251
Q

what is the main function of the wrist extensors?

A

position and stabilize the wrist during active flexion of the digits

252
Q

what are the primary (3) and secondary (5) wrist flexors?

A 
primary
(1) FCR
(2) FCU
(3) palmaris longus
secondary
(1) FDP
(2) FDS
(3) FPL
(4) APL
(5) extensor pollicis brevis
253
Q

what muscle has the greatest wrist flexion torque potential?

A

flexor carpi ulnaris

254
Q

how do the wrist flexors and extensors work synergistically during gripping or finger flexion motions?

A

with the wrist in neutral, the wrist flexors are on active insufficiency; gripping is most powerful with the wrist in 30 degrees of extension, so without the extensors, gripping wouldn’t be as effective

255
Q

when is gripping the strongest? the weakest?

A

(1) strongest in extension
(2) weakest in flexion
(neutral wrist strength falls between the two)

256
Q

what are the primary ulnar deviators? (2)

A

(1) FCU

(2) ECU

257
Q

which ulnar deviator has a longer moment arm and is in the best position to produce torque?

A

ECU

258
Q

what are the primary radial deviators? (3)

A

(1) FCR
(2) ECRB
(3) ECRL

259
Q

what can be said about the radial deviators and their moment arms?

A

the ECRB and ECRL have a similar moment arm to the FCR

260
Q

how much stronger are the flexors of the wrist when compared to the extensors?

A

70%

261
Q

list the groups of muscles at the wrist from strongest to weakest

A

(1) flexors (strongest)
(2) radial deviators
(3) ulnar deviators
(4) extensors (weakest)

262
Q

where does the proximal transverse arch of the hand go through? which bone is the keystone of this arch?

A

2nd carpal row; capitate

263
Q

where does the distal transverse arch of the hand go through? which bone is the keystone of this arch?

A

MCPs; 2nd and 3rd MCPs

264
Q

where does the longitudinal arch of the hand go through? which bone is the keystone of this arch?

A

2nd and 3rd rays; 2nd and 3rd MCP joint

265
Q

what is the purpose of the arches?

A

told fold and hold objects in the hand

266
Q

what can be said about the CMC joints of the hand in regards to available motion?

A
  • 2nd/3rd CMC: plane joints; 1 DOF (almost no motion)
  • 4th CMC: plane joint; 1 DOF (flex/ext can be observed)
  • 1st CMC: saddle joint; 2 DOF
267
Q

which CMC joints have the most motion and allow for closing of the hand (opposition)?

A

1st CMC
4th CMC
5th CMC

268
Q

which CMC joints have little to no motion?

A

2nd CMC

3rd CMC

269
Q

what ligaments provide stability to the CMC joints and prevent flexion and extension?

A

(1) dorsal / palmar carpometacarpal ligaments

(2) intermetacarpal ligaments

270
Q

in addition to the traditional movement of the MCP joints, how else can the joints be moved? (3)

A

(1) distracted / compressed
(2) A/P and lateral translations
(3) axially rotated
(joint mobs are commonly performed at this joint)

271
Q

at the MCP joint, what movement accompanies flexion?

A

external rotation

272
Q

at the MCP joint, what movement accompanies extension?

A

internal rotation

273
Q

how many DOF do the MCP joints have? (NOT including thumb)

A

2; flex/ext and add/abd

274
Q

how does the concave convex rule apply to the MCP joint? (NOT including thumb)

A

(1) during flexion / extension the roll and glide are the same direction
(1) during abduction / adduction roll and glide are the same direction

275
Q

what position is the MCP joint most stable?

A

full flexion, or 90 degrees (closed pack position); lateral ligaments are taut and prevent lateral movement

276
Q

what are palmar plates and what is their function?

A

(1) menicus-like structure made of fibrocartilage that help with joint congruence
(2) distribute stress on MCP surfaces which help prevent OA

277
Q

the collateral ligaments of the PIP and DIP joints are taut in what position?

A

full extension

278
Q

the collateral ligaments of the MCP joints are taut in what position?

A

full flexion

279
Q

what are the closed and open pack positions for the PIP and DIP joints?

A

closed pack: full extension

open pack: slight flexion

280
Q

what additional motion occurs at the PIP and DIP joints with flexion? what about extension?

A

(1) flexion: external rotation

(2) extension: internal rotation

281
Q

what can be said about the palmar plates (padding) between the IP joints compared to the MCP joint?

A

less padding between IP joints than MCP joints; IP joints are more prone to OA

282
Q

injuries at the IP joints are taped in what position? why?

A

full extension; prevent contractures and enhance joint stability during healing phase

283
Q

what type of joint is the CMC of the thumb? how many DOF does it have?

A

saddle joint; 2 DOF (flex/ext and add/abd)

*also known to have rotation which helps with opposition (technically has 3 DOF)

284
Q

how does the concave / convex rule apply to the CMC of the thumb?

A

SAGITTAL PLANE
flexion / extension glide is SAME the roll

FRONTAL PLANE
abduction / adduction glide is the OPPOSITE as the roll

285
Q

what are the movements that create opposition at the CMC of the thumb?

A

(1) abduction at the CMC joint

(2) flexion with IR at the CMC joint

286
Q

what 2 bones make up the articulation of the CMC joint?

A

(1) trapezium

(2) metacarpal

287
Q

what is closed pack position of the 1st CMC joint? what is open pack?

A

closed: extreme opposition
open: neutral

288
Q

what ligament prevents separation between the 1st and 2nd CMC joints?

A

intermediate ligament

289
Q

what are 2 common pathologies at the CMC joint?

A

(1) notorious for developing OA

2) sprain of UCL (ulnar/medial collateral ligament

290
Q

how much flexion and extension does the MCP of the thumb have?

A

flexion: 30-60 degrees
extension: 0-15 degrees

291
Q

what is the function of the MCP joint of the thumb?

A

provide further flexion during thumb opposition

292
Q

what can be said about the capsule of the MCP of the thumb?

A

stronger than the MCP joints of the fingers; reinforced by sesamoid bones (palmarly)

293
Q

what are the extrinsic flexors of the fingers? (3)

A

(1) FDS
(2) FDP
(3) flexor palmaris longus

294
Q

what is the main function of the FDS? can each tendon be controlled independently?

A

(1) flex the PIP joints (except the 5th digit)

(2) each PIP can be flexed independently

295
Q

what is the main function of the FDP? can each tendon be controlled independently?

A

(1) flex the DIP joints

(2) the FDP of the index finger can be independently controlled; the other 3 tendons are connected

296
Q

what are the actions of the flexor pollicis longus? (3)

A

(1) flex CMC of thumb
(2) flex MCP of thumb
(3) flex IP of thumb
(4) flex and radially deviate the wrist

297
Q

how many annular ligaments do each of the 4 fingers have? how many cruciate ligaments?

A

5 annular ligaments (pulleys) (A1-A5)

3 cruciate ligaments

298
Q

how many annular ligaments does the thumb have? how many oblique ligaments?

A

2 annular ligaments (pulleys) (A1-A2)

1 oblique ligament

299
Q

what do they pulleys do?

A

make muscle contraction more efficient

300
Q

what are the extrinsic extensors of the fingers? (3)

A

(1) extensor digitorum
(2) extensor indicis
(3) extensor digiti minimi

301
Q

what muscle extends the MCPs of the fingers

A

extensor digitorum

302
Q

how does the extensor hood extend the PIP and DIP joints? (4)

A

(1) intrinsic muscles (lumbricals) contract
(2) this causes the PIP to extend
(3) which causes oblique retinacular ligament to stretch
(4) which extends the DIP

303
Q

what are the actions of the extensor pollicis longus? (4)

A

(1) extend the CMC of thumb
(2) extend the MCP of thumb
(3) extend the IP of thumb
(4) adduct CMC when CMC is abducted

304
Q

what are the actions of the extensor pollicis brevis? (2)

A

(1) extend the CMC of thumb

(2) extend the MCP of thumb

305
Q

what are the extrinsic muscles of the thumb? (4)

A

(1) EPL
(2) EPB
(3) APL
(4) FPL

306
Q

how many intrinsic muscles does the hand have? what are the 4 sets?

A

20; divided into 4 sets

(1) thenar
(2) hypothenar
(3) adductor pollicis
(4) lumbricals and interossei

307
Q

what is the purpose of the thenar muscles of the hand?

A

position the thumb to facilitate grasping

308
Q

what is the purpose of the hypothenar muscles of the hand?

A

deepens transverse arch of the hand and enhances contact to hold objects

309
Q

what is the function of the oblique and transverse heads of the adductor pollicis?

A

(1) BOTH heads flex and adduct the CMC

(2) BOTH heads flex the MCP

310
Q

which head of the adductor pollicis is stronger (can produce more torque)?

A

transverse head

311
Q

what is the function of the lumbricals of the hand?

A

flex the MCP joints and extend the PIP and DIP joints (by pulling on lateral band extensor hood)

312
Q

which MCP joints do the palmar interossei adduct?

A

2nd, 4th, 5th

313
Q

why don’t the dorsal interossei abduct the 5th digit?

A

it has it’s own abductor (abductor digiti minimi)

314
Q

which interossei are bipennate?

A

the dorsal interossei

315
Q

in addition to abducting and adducting the fingers, what other function do they interossei assist with?

A

(1) MCP flexion
(2) PIP and DIP extension
(same action as the lumbricals)

316
Q

which muscle is in a better position to produce a flexion torque at the MCP, the lumbricals or interossei?

A

the lumbricals

317
Q

what do hand intrinsic and extrinsic muscles work synergistically to do?

A

open and close the digits of the hand (wrist extensors and finger flexors)

318
Q

what are the steps involved with opening the hand? (3)

A

(1) early phase - ED extends the MCPs
(2) middle phase - lumbricals / interossei assist ED and extend PIP and DIP; also prevent MCP from hyperextending MCPs
(3) late phase - wrist flexors pull the wrist in slight flexion; this allows ED to fully extend fingers

319
Q

what are the steps involved with closing the hand? (2)

A

(1) early phase - FDS, FDP, interossei flex PIP and DIP

(2) late phase - wrist extensors slightly extend the wrist; finger flexion continues and ED decelerates flexion of MCPs

320
Q

what synergistic action is required for finger extension?

A

wrist flexion

321
Q

what synergistic action is required for finger flexion?

A

wrist extension

322
Q

what is the extrinsic plus position? what is the intrinsic plus position?

A

extrinsic plus
(1) MCPs extended, PIP and DIP flexed
intrinsic plus
(1) MCPs flexed, PIP and DIP extended

323
Q

what can happen when the intrinsic muscles of the hand don’t work?

A

(1) can’t control MCP flexion

(2) can’t extend PIP and DIP

324
Q

what part of the body has a lot of motor control from the motor cortex of the brain?

A

the hand

325
Q

what joint is most prone to instability and ligament tears in the hand?

A

midcarpal joint

326
Q

is carpal instability static or dynamic?

A

it can be static, dynamic, or both

327
Q

what are 3 common instabilities of the wrist?

A

(1) dorsal intercalated segment instability
(2) volar intercalated segment instability
(3) ulnar translocation of carpus

328
Q

which row of carpals is more mobile?

A

the proximal row

329
Q

where does zig-zag carpal instability occur?

A

midcarpal joint between distal and proximal carpal rows

330
Q

what occurs during dorsal intercalated segment instability? what causes this?

A

capitate glides dorsally; tear of scapholunate ligament

331
Q

volar intercalated segment instability? what causes this?

A

capitate glides volarly; tear of lunotriquetral ligament

332
Q

what is Kienbock’s disease?

A

avascular necrosis of the lunate

333
Q

can spinal segments be moved individually?

A

no; movement of the spine involves several vertebral segments

334
Q

where are the areas where load is transitioned in the spine? what are these areas prone to?

A

the curvatures; prone to dysfunction and pain

335
Q

which curvatures are prone to dysfunction? (3)

A

(1) suboccipital
(2) CT junction
(3) LS junction
* TL junction isn’t prone to injury

336
Q

how does each main curvature of the spine develop?

A

(1) cervical lordosis: as an infant, trying to keep the head up while lying prone
(2) thoracic kyphosis: when child learns to sit up
(3) lumbar lordosis: when child starts to walk

337
Q

what is the purpose of the curvatures of the spine?

A

absorb load, make the spine flexible, and dampen shock

338
Q

how would you describe the height of the vertebral discs in the C/S, T/S and L/S?

A

(1) C/S - discs taller anterior than posterior
(2) T/S - disc height is even
(3) L1 - L3 taller posterior
L3 - L4 even
L4-S1 taller anteriorly

339
Q

what can a flat cervical lordosis cause?

A

headaches

340
Q

what can an increased thoracic kyphosis cause?

A

neck pain

341
Q

what can an increased lumbar lordosis cause?

A

nerve root compression

342
Q

where does the vertebral artery typically run?

A

C1-C6

343
Q

what motions are known to occlude the vertebral artery and block blood flow to the brain?

A

extreme ranges of cervical extension and rotation

344
Q

is the thoracic spine designed for mobility or stability?

A

stability; ribs provide stability but limit mobility (reduced rotation)

345
Q

what type of joints are facet joints of the spine? do they follow the concave convex rule?

A

plane synovial joint; they don’t follow concave convex rule

346
Q

what segments of the spine have fat pads and a meniscus to help reduce compressive forces around the joints?

A

(1) cervical spine

(2) lumbar spine

347
Q

what is the only segment of the spine to follow the concave/convex rule?

A

occiput / C1

348
Q

what segment is responsible for the greatest amount of cervical rotation?

A

C1/C2

*50% of cervical rotation comes from this segment

349
Q

what type of motion is favored with transverse, sagittal, and frontal facet orientations?

A

(1) transverse facets favor rotation
(2) sagittal facets favor flexion and extension
(3) frontal facets favor side bending

350
Q

which segment allows for more side bending, the cervical spine or lumbar spine?

A

cervical spine

351
Q

with the exception of C1/C2, what does each vertebral segment have?

A

(1) two synovial joints

(2) one symphysis

352
Q

what is the function of the nucleus pulposus?

A

works to absorb shock by dissipating and transferring loads across the vertebrae

353
Q

what type of collagen is the annulus fibrosus primarily composed of?

A

type I collagen (structure is similar to ligaments)

354
Q

what makes up majority of the nucleus pulposus? what type of collagen is more abundant in this structure

A

(1) proteoglycans (maintain positive pressure)

(2) type II collagen

355
Q

how are the fibers of the annulus fibrosus oriented in the lumbar spine? what problems can this cause?

A

(1) criss-crossed
(2) only 50% of the collagen fibers are tense during lumbar rotation while the other 50% are relaxed, which can cause damage to the disc with rotation

356
Q

is the NP/AF higher in the cervical or lumbar spine? what are the implications of this?

A

(1) lumbar spine

(2) because the L/S has a larger nucleus pulposus, it’s more prone to disc herniation

357
Q

where is the annulus fibrosus of the cervical spine strongest? weakest?

A

(1) strongest: anteriorly

(2) weakest: posterior and laterally

358
Q

what structure helps prevent posterio-lateral disc herniations of the cervical spine?

A

u-joints

359
Q

what is the orientation of the annulus fibrosus of the cervical spine? (2)

A

(1) anterior: criss-cross (resists compression and tension)

2) posterior: longitudinal (resists flexion and tension

360
Q

are herniations more common in the upper or lower cervical spine? why?

A

(1) lower

(2) U-joints are less developed the further down the C/S you go

361
Q

during flexion, what happens to the AF and NP at the lumbar spine?

A

(1) AF: compressed anteriorly and tensioned posteriorly

(2) pushed posteriorly

362
Q

during rotation, what happens to the AF at the lumbar spine?

A

internal shearing force

363
Q

where are the vertebrae most vulnerable to fracture?

A

anterior portion of vertebral body (stress isn’t applied here as often so bone is weaker)

364
Q

is disc pressure higher with sitting or standing?

A

disc pressure is higher SITTING than it is during standing or walking

365
Q

is disc pressure higher with standing or lying down?

A

standing

366
Q

what sitting position decreases disc pressure? what seated position increases disc pressure?

A

(1) decreases: reclined

(2) increases: slouched

367
Q

when lifting, what technique reduces pressure on the discs?

A

bending the knees to lift an object

368
Q

what movement causes greater torque (stress) on the upper cervical spine? lower cervical spine?

A

(1) lower cervical: during flexion (looking down)

2) upper cervical: during extension (looking up

369
Q

what movements accompany protraction of the head? (2)

A

(1) upper C/S extends

(2) lower C/S flexes

370
Q

what movements accompany retraction of the head? (2)

A

(1) upper C/S flexes

(2) lower C/S extends

371
Q

why does poor sitting posture tend to cause added stress and pain?

A

it moves the line of gravity further from the center of gravity

372
Q

how many DOF does the spine have?

A

3

373
Q

what way do the facets glide with flexion of the lumbar spine?

A

superiorly and anteriorly

374
Q

what happens to the intervertebral foramen and vertebral canal during lumbar flexion?

A

(1) intervertebral foramen: widen (vertically)

2) vertebral canal: widens (vertically and horizontally

375
Q

what way do the facets glide with extension of the lumbar spine?

A

posteriorly and inferiorly

376
Q

how does the superior vertebral body glide on the inferior vertebral body during lumbar extension?

A

posterior glide

377
Q

what happens to the intervertebral foramen and vertebral canal during lumbar extension?

A

both canals narrow

378
Q

what way do the facets glide with rotation of the lumbar spine?

A

(1) ipsilateral stretch of the facet capsule

(2) contralateral compression of facet joint

379
Q

what happens to the intervertebral foramen during lumbar rotation?

A

(1) ipsilateral foramen widens

(2) contralateral foramen narrows

380
Q

how does the superior vertebral body glide on the inferior vertebral body during lumbar rotation?

A

ipsilateral side glides posteriorly

381
Q

what way do the facets glide with side flexion of the lumbar spine?

A

(1) ipsilateral inferior glide of the facet

(2) contralateral superior glide of the facet

382
Q

what happens to the intervertebral foramen during lumbar side flexion?

A

(1) ipsilateral foramen narrows

(2) contralateral foramen widens

383
Q

what is the roll and glide of the occiput on C1?

A

roll and glide are opposite

CONVEX facets of occiput
move on
CONCAVE facets of C1

384
Q

what accessory movements occur at C1/C2 with flexion and extension?

A

(1) small anterior tilt with flexion
(2) small posterior tilt with extension
* no A/P or P/A glides at this joint

385
Q

what way do the facets glide with flexion of the lower cervical spine?

A

superiorly and anteriorly

386
Q

how does the superior vertebral body glide on the inferior vertebral body during flexion of the lower cervical spine?

A

anteriorly

387
Q

what happens to the intervertebral foramen and vertebral canal during flexion of the lower cervical spine?

A

(1) intervertebral canal: widens

(2) vertebral canal: narrows

388
Q

in what population can extreme cervical flexion or extreme extension damage the spinal cord?

A

elderly and patients with arthritis of the spine; osteophytes develop in the vertebral canal

389
Q

what way do the facets glide with extension of the lower cervical spine?

A

posteriorly and inferiorly

390
Q

how does the superior vertebral body glide on the inferior vertebral body during extension of the lower cervical spine?

A

posteriorly and inferiorly

391
Q

what happens to the intervertebral foramen and vertebral canal during extension of the lower cervical spine?

A

(1) intervertebral canal: narrows

2) vertebral canal: narrows (more than with flexion

392
Q

what way do the facets glide with rotation of the lower cervical spine?

A

(1) ipsilateral facets glide inferiorly and posteriorly
(2) contralateral facets glide superiorly and anteriorly

*facets don’t jam like in the lumbar spine

393
Q

what happens to the intervertebral foramen and vertebral canal during rotation of the lower cervical spine?

A

(1) ipsilateral foramen narrows
(2) contralateral foramen widens
(3) vertebral canal isn’t affected much with rotation

394
Q

what percentage of cervical rotation comes from C1/C2? what about C2-C7?

A

(1) C1/C2 provides 50% of cervical rotation

(2) C2-C7 provides 50% of cervical rotation

395
Q

what way do the facets glide with side flexion of the lower cervical spine?

A

(1) ipsilateral facets glide inferiorly and posteriorly

(2) contralateral facets glide superiorly and anteriorly

396
Q

what happens to the intervertebral foramen during cervical side flexion?

A

(1) ipsilateral foramen narrows

(2) contralateral foramen widens

397
Q

do side bending and rotation of the LOWER cervical spine occur in the same or opposite directions?

A

same direction

398
Q

do side bending and rotation of the lumbar spine occur in the same or opposite directions?

A

(1) same direction if facets are touching

(2) opposite direction if facets are NOT touching

399
Q

do side bending and rotation of the UPPER cervical spine occur in the same or opposite directions? at what levels do these movements occur?

A

opposite directions

(1) rotation occurs at C1/C2
(2) side flexion occurs at Occiput/C1

400
Q

what direction do the condyles of the occiput glide with side flexion?

A

opposite direction of the roll; remember the concave / convex rule for occiput and C1

401
Q

why is it important that the movements of the upper cervical spine are coupled?

A

to keep your eyes level with the horizon when you side bend or rotate your head

402
Q

what way do the facets glide with rotation of the upper cervical spine?

A

(1) ipsilateral facet (of C1) glides posteriorly

(2) contralateral facet (of C1) glides anteriorly

403
Q

when you ROTATE your head RIGHT, what happens both osteokinematically and arthokinematically?

A

Rotation to the right occurs
Side flexion to the left occurs

(1) Occ/C1: right facet moves posterior, left facet moves anterior
(2) occipital condyles glide RIGHT (because side flexion is left)

404
Q

when you SIDE BEND your head RIGHT, what happens both osteokinematically and arthokinematically?

A

Rotation to the left occurs
Side flexion to the right occurs

(1) Occ/C1: left facet moves posterior, right facet moves anterior
(2) occipital condyles glide LEFT (because side flexion is right)

405
Q

what vertebrae have more flexion / extension, the thoracic or lumbar segments?

A

lumbar segments

406
Q

what vertebrae have more rotation, the thoracic or lumbar segments?

A

thoracic segments

407
Q

what segment of the C/S has the least amount of rotation?

A

Occiput/C1

408
Q

what segment of the spine has the most side flexion?

A

cervical segments

409
Q

where is the center of gravity located in the body? what can be said about this area?

A

(1) anterior to S2 within the sacroiliac ring

(2) tends to be a very stable area with less motion

410
Q

what is the keystone for motion between the upper and lower body?

A

the sacrum

411
Q

what happens during sacral nutation?

A

(1) sacrum flexes

(2) pelvis tilts posteriorly

412
Q

what happens during sacral counternutation?

A

(1) sacrum extends

(2) pelvis tilts anteriorly

413
Q

what are the phases of the lumbosacral rhythm?

A

from full trunk flexion to full trunk extension

(1) initial phase: hip extensor muscles initial extension
(2) shared activation of hip and lumbar extensors extend the hip trunk further
(3) muscle activity ceases once LOG falls posterior to hips

414
Q

when there is limited flexion of the hips (tight hamstrings), what compensation occurs?

A

increased flexion of the lumbar and lower thoracic spines

415
Q

when lumbar spine mobility is limited, what compensation occurs?

A

increased flexion of the hip joint

416
Q

what are the muscles of the back designed for?

A

to provide stability

417
Q

what muscle action does the SCOM perform unilaterally (3) and bilaterally (1)?

A 
unilateral
(1) ipsilateral side flexion 
(2) contralateral rotation 
(3) extension of the head
bilateral
(1) flexion of cervical spine
418
Q

what muscle action do the scalenes (3) perform unilaterally and bilaterally (1)?

A

unilateral
(1) anterior: side flexion; contralateral rotation
(2) middle: stabilizer
(3) posterior: ipsilateral lateral flexor
bilateral
(1) flexion

419
Q

what muscle action do the longus capitis & colli perform? (1)

A

(1) stabilize head and neck

420
Q

what muscle action do the rectus capitis anterior and lateralis perform? (2)

A

(1) primary: stabilizer

(2) secondary: flexion

421
Q

which cervical extensors perform ipsilateral rotation? (2)

A

(1) Splenius capitis and cervicis

(2) suboccipital muscles

422
Q

which cervical extensors perform ipsilateral side flexion? (2)

A

(1) longissimus capitis and cervicis

(2) traps

423
Q

which cervical extensors perform contralateral rotation? (1)

A

(1) traps

424
Q

which cervical extensors are in optimal alignment for extension? (1)

A

(1) semispinalis capitis and cervicis

425
Q

where does the LOG fall for the AO joint? what does that mean from a muscle standpoint?

A

(1) anterior

(2) produces a flexion moment, meaning the extensors have to fire

426
Q

forward head posture increases the activity of what muscles?

A

extensors; to keep the head upright

427
Q

how does forward head posture affect the lower segments of the spine?

A

(1) increased kyphosis of T/S
(2) anterior pelvic tilt
(can cause mid back and low back problems)

428
Q

what muscle can act as both a hip flexor and hip extensor?

A

psoas major

429
Q

what controls trunk flexion from upright to full flexion for the first half of the motion? the second half of the motion?

A

(1) first half: eccentric contraction of the extensors AND posterior ligaments and discs
(2) second half: posterior ligaments and discs

430
Q

what are the main muscles that contract ipsilaterally (2) and contralaterally (3) during trunk rotation?

A

ipsilateral side

(1) internal oblique
(2) lats

contralateral side

(1) external oblique
(2) traps
(3) gluteus maximus

431
Q

what are the muscles that contract during side flexion?

A

(1) contralateral QL

(2) contralateral psoas major

432
Q

what muscles initiate trunk flexion when doing a sit-up? what muscles kick in a little later?

A

(1) abdominals and obliques initiate flexion

(2) hip flexors kick in later

433
Q

when performing an oblique crunch, which muscles work synergistically unilaterally (2) and synergistically bilaterally (2)?

A 
unilateral
(1) ipsilateral internal oblique
(2) contralateral external oblique
bilateral
(1) rectus abdominis
(2) transversus abdominis
434
Q

which deep muscles of the spine provide motor and sensory feedback and are well developed in the cervical spine? (2)

A

(1) interspinalis

(2) intertransvesarius

435
Q

how does the position of an object affect muscle activity when lifting it off the ground?

A

if the object is further away, it increases the external moment and puts added stress on the muscles and passive structures of the spine

436
Q

how can you reduce the compression of the spine during lifting activities? (4)

A

(1) reduce the load
(2) decrease external MA
(move object closer)
(3) increase internal MA (squat lower)
(4) lift in a slow controlled motion

437
Q

why is a golfer’s lift (single-leg RDL) recommended for picking up small, light objects?

A

extension of the leg reduces the flexion moment on the muscles and discs of the spine

438
Q

generally speaking, where does most back pain stem from?

A

the joints and discs, not the muscles

439
Q

poor posture and chronic pain can lead to the deactivation of which muscles of the spine?

A

typically deeper muscles will get weaker, and don’t fire as much (multifidi, transverse abs, longus colli, etc.)

440
Q

what structure of the lumbar spine is pulled on by the muscles to keep the vertical column erect?

A

thoracolumbar fascia

441
Q

what are the main deep stabilizers of the lumbar spine? (2)

A

(1) multifidus

(2) transverse abdominals

442
Q

what are the main deep stabilizers of the cervical spine? (3)

A

(1) longus capitis
(2) longus colli
(3) multifidus

443
Q

what are the main rotators of the trunk? (2)

A

internal and external obliques

444
Q

what muscle attaches to and protects the facet capsules during motion

A

multifidus

445
Q

what are the functions of the spinal ligaments? (4)

A

(1) limit motion
(2) maintain spinal curvatures
(3) stabilize the spine
(4) protect spinal cord, roots, and vessels

446
Q

what is the function of ligamentum flavum? what is it composed of? where is it the thickest?

A

(1) function: decelerates lumbar flexion
(2) high percentage of elastin (recoils in extension)
(3) lumbar spine

447
Q

what is the function of the supraspinous and interspinous ligaments?

A

limit forward flexion

448
Q

what is the function of the intertransverse ligament? (2)

A

(1) limit forward flexion

(2) limit contralateral side flexion

449
Q

what is the function of the anterior longitudinal ligament? (3)

A

(1) prevents hyper extension
(2) maintains lordosis
(3) protects discs anteriorly

450
Q

what is the function of the posterior longitudinal ligament? (2)

A

(1) limits flexion

(2) reinforces posterior rise of intervertebral discs

451
Q

what is the function of the facet capsules?

A

supports the facets and become taut in any position other than neutral

452
Q

what are the main ligaments responsible for stability of the upper cervical spine?

A

(1) cruciform ligament
(2) alar ligament
(3) tectorial membrane
* cruciform ligament is most important

453
Q

what is the most important ligament for keeping the odontoid process in check?

A

transverse ligament

454
Q

what is one reason children have more mobility in their lumbar spine and are more prone to spondys than adults?

A

the iliolumbar ligament doesn’t develop until your twenties and this ligament adds stability to the lumbosacral area

455
Q

what is the function of the anterior sacroiliac ligament?

A

reinforce and add stability to the anterior side of the SI joint

456
Q

what is the strongest ligament of the SI joint? what’s it’s function?

A

(1) interosseous ligament

(2) binds the sacrum with the ilium

457
Q

what is the function of the posterior sacroiliac ligament?

A

limits sacral translation

458
Q

what is the function of the sacrotuberous ligament?

A

limits sacral nutation

459
Q

how many capsules / ligaments are present in alls segments of the spine?

A

6

460
Q

what ligament is important to maintain anterior stability of L4/L5 an L5/S1 segments?

A

iliolumbar ligament

Biomechanics (4 decks)

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