the shoulder complex Flashcards

1
Q

how many joints make up the shoulder?

A

3:
- sternoclavicular
- glenohumeral
- acromioclavicular
1 pseudo:
- scapulothoracic

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2
Q

what makes up the “shoulder girdle”

A

scapula
clavicle
manubrium

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3
Q

where is the manubrium?

A

sternal/ jugular notch b/n clavicular facets
- connection point b/n appendicular and axial skeleton

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4
Q

clavicle:
what does the outwards curve protect?
how does it help us absorb impact?

A
  1. major neurovasculature bundles travel up
  2. force travels from hand up to clavicle and scapula, then diffused through muscles
    - sits above transverse plane, 20 degrees to frontal plane
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5
Q

what does the scapula provide regarding GH muscles and joint?

A
  • location for GH muscles to originate
  • stable base from which GH joint can operate
  • works w clavicle to enhance shoulder ROM
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6
Q

significant muscle/group living on scapula:

A
  • rotator cuff
  • serratus anterior (vert border on thoracic aspect)
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7
Q

where does the long head of the biceps tendon originate?

A

supraglenoid tubercle

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8
Q

where does the long head of the triceps tendon originate?

A

infraglenoid tubercle

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9
Q

what does the labrum of the glenoid fossa allow for?

A

deepens fossa by 50%

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10
Q

“plane of scapula” or plane of scaption:

A

sits in middle of frontal and sagittal plane ~45 degrees b/n

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11
Q

where is the anatomical vs surgical neck of the humerus?

A

anatomical = immediately beneath head, where joint capsule of shoulder has insertion point
surgical = below, where fracture ysyally happens

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12
Q

how does the head of the humerus sit to articulate w the fossa?

A

rotate head back to sit on fossa
(laterally, superiorly, and anteriorly)

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13
Q

what is “angle of inclination” ?
what plane does is occur?
angle?

A

angle b/n humeral head and shaft relative to shaft
frontal plane
135 degrees

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14
Q

what is “angle of torsion” ?
what plane does is occur?
angle?
allows for?

A

torsion = twist
how humeral head is angled posterior relative to distal condyles
transverse plane (head in scapular plane while elbow neutral)
allows for greater ROM in abduction and ER before impinging

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15
Q

main movements of shoulder girdle:

A

elevation/ depression
protraction/ retraction
upward/ downward rotation
scapular tilting/ tipping

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16
Q

what joint connects the arm to the skeleton?

A

sternoclavicular

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17
Q

depression and elevation
due to:
ROM:
joints involved:
examples

A

upward/ downward scapular glide
up 60 degrees, down 5-10 degrees
psuedo, SC, AC
shrug vs crutches/ push out of chair

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18
Q

what do tilt and rotation help maintain scap contact w?

A

thorax

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19
Q

protraction/ retraction
measure of:
due to:
ex:

A

how far scapulae move away from spine
forward glide/ abduction of lat clavicle & scap
backward glide/ adduction of lat clavicle&scap
ex: reach arms forward vs pinch shoulder blades together

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20
Q

what joint motions are responsible for maintaining scapular contact w torax?

A

AC and SC

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21
Q

upward/ downward rotation
how does it allow for full GH flexion/ extension?
joints? movement?

A

upward rotation = scap moves superiorly and rotates underneath toward armpit to spot head of humerus
elevation/ depression of AC&SC

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22
Q

types of scapular tilt/tip:
named how?

A
  1. anterior-posterior
  2. medial-lateral
    name according to where superior angle of scap goes
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23
Q

sternoclavicular joint:
connects?
what type?
DOF

A

manubrium & 1st rib - connection b/n axial and appendicular skeleton
synovial, complex, modified saddle
3 - elevation/ depression, protraction/ retraction, rotation

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24
Q

purpose of SC disc (4):

A
  • separates joint into 2 cavities
  • serves as a hinge = motion occurs b/n clavicle&dic and disc&sternum
  • adds stability = reduce medial sliding to protect trachea
  • reduces joint stress - has potential for arthritis
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25
Q

which capsular ligaments strengthen the SC capsule?
how?
which is extracapsular?

A
  • A/P SC
  • interclavicular = prevents upward displacement
  • anteriorly, posteriorly, and superiorly
    -costoclavicular = restricts clavicle elevation, rotation, medial/lateral motion
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26
Q

describe the costoclavicular ligament

A
  • restricts clavicle elevation, rotation, medial/lateral motion
  • 2 crossing heads = stronger, dissapates force
  • origin of sternocleidomastoid - provides additional support
  • reinforced by subclavius
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27
Q

what limits elevation vs depression of SC?

A

elevation = costoclavicular ligament and subclavius
depression = interclavicular ligament and first rib

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28
Q

predominant SC joint motion:

A

protraction/ retraction
- accompanied by scap pro/retraction

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29
Q

what movement does posterior SC rotation accompany?
due to?

A

GH elevation (anytime you bring arm up)
tightening of trapezoid and conoid ligaments

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30
Q

when does the conoid become an axis?
effect?

A

as it tightens during second 90 degrees of shoulder elevation
improves GH elevation

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31
Q

what arthrokinematic motions does the SC joint do?

A

all
- roll
- glide
- spin

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32
Q

resting vs close packed position of SC

A

resting = arm by side
closed packed = hiked up by ear bc conoid has locked the AC joint and created axis, provides rest of ROM

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33
Q

acromioclavicular joint
type:
DOF:
primary function:

A

plane synovial joint
3
(lined w fibrocartilage)
increases ROM of humerus in glenoid - allows scapula to maintain thoracic contact throughout ROM
**no muscular connections move this

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34
Q

which capsular ligaments strenghten AC capsule? in which ways?

A

superior and inferior AC ligaments
inferiorly and superiorly (often gets damaged)

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35
Q

which ligaments are key in AC joint stability?

A

coracoclavicular - stronger than AC ligament, limits excessive AC motion
1. conoid = checks superior clavicular motion
2. trapezoid = prevents lateral clavicle motion on acromion

36
Q

osteokinematic AC motions:
aka?

A

scapular motions
- elevation/ depression
- abduction/ adduction
- upward/ downward rotation - allows clavicle to rise and roll

37
Q

small but key adjustments done by AC:

A
  • keep fossa and head aligned during GH elevation
  • M/L tilt move vertebral border toward/ away from posterior thorax
  • A/P tilt
38
Q

AC resting vs closed packed position:

A

resting = arm by side
close packed = 90 degrees abduction (after that conoid provides axis for SC to anchor for max ROM)

39
Q

Scapulothoracic
type:
what does it show/ represent?
(separated by?)
is it needed?

A

psuedo joint
represents articulation b/n scap and thorax
- scapula = concave
- thorax = convex
(bursa, serratus anterior, subscapularis, fascia)
- needed for full GH motion

40
Q

ST function:

A
  • enhance shoulder ROM**
  • stability = length-tension relationship of rotator cuff/ deltoid
  • position glenoid to receive humeral head
  • absorb shock - FOOSH
  • push out of chair
41
Q

2 muscles jobs during initial abduction:

A

supraspinatus = primary role is first 30 degrees (sucky rotator)
deltoid = stabilize by lifting up and pulling humerus into fossa

42
Q

combined motion of what joints directly results in ST motion?

A

AC and SC

43
Q

ST joint motions:

A

SC = 30 degrees joint elevation
AC = 30 degrees joint upward rotation
= 60 degrees
- protraction/ retraction = AC and SC determine if joint can move

44
Q

where is the subscapular bursa?
function?

A
  • lies over anterior joint capsule, beneath tendon of subscapularis muscles
  • communicates w joint capsule to maintain neg pressure w/n joint - try to keep joint in place - balanced flow
45
Q

glenohumeral joint
type:
DOF:
mobile?

A

ball and socket, synovial
3 (flex/ex, ab/duction, med/lat rotation0
highly mobile = unstable

46
Q

what/ where is the labrum?

A

fibrocartilanginous rim attached to glenoid, continous w long head tendon of biceps
- protects the edges of the bone

47
Q

GH joint capsule:
size/shape/thickness
attaches where?
ligaments and tendons separate or blend??

A

large fibrous cylinder, thin&loose
attached from glenoid rim to anatomical neck
ligaments and tendons blend

48
Q

inferior axillary recess:
where?
function?

A

= bottom armpit space
need extra space/ laxity in capsule for head to move into glenoid fossa
“redundant inferiorly”

49
Q

GH reinforcements:

A
  1. superior/middle/inferior GH ligaments
  2. coracohumeral ligament
  3. long head of triceps/ biceps (hold up humeral head)
  4. rotator cuff tendons (hold head in socket) blend w capsule
50
Q

superior GH ligament
relative size:
where:
supports?
limits:

A

smallest thickening of capsule
base of coracoid process to MGHL, biceps tendon, & labrum
supports hanging arm
limits anterior translation and external rotation to 45 degrees of abduction + (inferior translation in adduction)

51
Q

middle GH ligament
where:
limits:
supports?
area of strength or weakness?

A

attached to anatomical neck (medial to lesser tuberosity)
limits ER b/n 45-90 degrees of abduction
supports hanging arm
area of weakness
(feeds into subscapularis bursa, “foramen of weitbrech)

52
Q

function of superior and middle GHL:

A

stop too much external rotation (a vulnerable position for shoulder)
ex: foosh, arm caught and pulled too far

53
Q

inferior GH ligament
relative size:
where:
how is it “redundant”?
what degree of abduction does primary support begin at?

A

thickest of GH capsule
from labrum or glenoid neck
2 bands = cradle/ sling to keep arm up
above 90 degrees abduction

54
Q

coracohumeral ligament
origin/insertion:
limits:
supports?

A

originates on (posterolateral) coracoid
inserts on greater tuberosity (lateral to bicipital groove)
limits:
- external rotation when arm is neutral
- posteroinferior shift of humeral head
supports hanging arm

55
Q

where are long heads of biceps and triceps?

A

biceps = supraglenoid tubercle
triceps = infraglenoid tubercle

56
Q

rotator cuff tendons: (4)

A

SSIT:
Subscapularis
Supraspinatus
Infraspinatus
Teres minor

57
Q

which rotator cuff tendon prevents external rotation and why?

A

subscapularis = active INTERNAL rotator + passive stabilizer

58
Q

which rotator cuff tendons limit internal rotation?

A

infraspinatus and teres minor = active EXTERNAL rotators

59
Q

what does the coracoacromial arch form?
what tendons does it protect?

A

a roof over GH joint
protects
- supraspinatus
- long head of biceps
- subacromial bursa
- superior capsule

60
Q

how many GH bursae are there &what are the 2 most noteable?

A

8
subacromial and subdeltoid

61
Q

where are subacromial and subdeltoid bursae?
function?
separate or continous?

A

over supraspinatus tendon and deltoid beneath acromion
decrease friction in joint (w/o = impingement)
continuous

62
Q

GH joint osteokinematic DOF’s:

A
  1. ab/duction
    - in frontal plane
    - horizontal = in transverse plane
  2. flexion/ extension in sagittal plane
  3. medial/ lateral rotation in transverse plane (affected by forearm pronation/ supination)
63
Q

what does movements does max GH flexion elevation require?

A
  • GH rotation
  • posterior scapular tilting
  • upward rotation
64
Q

arthrokinematic GH movements:

A
  • flexion/extension = spin (anterior/posterior slide)
  • ab/duction = superior/inferior roll, inferior/upward glide
  • lateral/ medial rotation = posterior/anterior roll, anterior/ posterior glide
65
Q

GH resting position:

A

20-30 degrees of horizontal adduction
55 degrees of flexion

66
Q

GH closed packed position:

A

full abduction, external rotation

67
Q

what is the bicipital grrove?

A

where biceps tendon is restrained by coracohumeral and transverse humeral ligament
(humerus moves on tendon during shoulder motion)

68
Q

setting phase:
what is the ratio of degrees of humerus to scapula movement after this?

A

early phase of abduction - first 30 degrees
2:1

69
Q

what joint provides first 120 degrees?
remaining 60 degrees?

A

GH
AC + SC

70
Q

where does axis of rotation of scapula migrate during elevation?

A

start at root of scap spine, moves laterally toward AC joint

71
Q

scapular stabilizer muscles (1 inch punch):

A
  • serratus anterior = primary scapular protractor (usually too weak/ tight)
  • trapezius (shrug/retract/depress)
  • rhomboid major/ minor
  • pectoralis minor (scap depression +downward rotation)
  • levator scapulae (elevator/ depressor, both = neck extender)
72
Q

glenohumeral stabilizers:
main function?

A

for initial abduction
1. supraspinatus
2. infraspinatus/ teres minor
3. subscapularis (depends on arm positionpassive support at insertion)
4. biceps (hold humerus head up and in) /triceps brachii (stabilize - cradle ligaments)

73
Q

“large mover” muscles:

A

deltoid (heads on clavicle, acromion process, scap)
latissimus dorsi (big flat)
teres major (+ lats = handcuff muscles)
pectoralis major (heads on clavicle&sternum)
coracobrachialis (off coracoid process)

74
Q

passive stabilization at
SC and AC
GH and scapulothoracic

A

SC and AC = ligamentous support - bony configuration
GH and ST = muscular support

75
Q

dynamic stabilizers:

A

upper trapezius = low activity at rest
rotator cuff = compressive stabilizers
biceps = compress humeral head
deltoid

76
Q

rotator cuff muscles

A
  • supraspinatus
  • infraspinatus
  • teres minor
77
Q

when arm up, which muscles work together like couples yoga

A

deltoid and rotator cuff - synergistic

78
Q

what happens when serratus anterior, upper and lower trap fire (synergistic)?

A

upward scapular rotation = scapula rolls so inferior angle moves towards axilla

79
Q

what happens when pec minor, levator scapulae and rhomboids fire (synergistic)?

A

downward scapular rotation = guide inferior angle of scap towards vertebra

80
Q

what allows the rotator cuff to maintain long moment arm over a greater range?

A

scapular rotation

81
Q

does supraspinatus or deltoid have greater leverage?

A

suprapinatus = bc lever arm length is constant throughout elevation ROM (deltoids increases)

82
Q

what is needed for perfect shoulder elevation?

A

upper t spine - full extension
GH - full flexion and abduction
ST - full upward rotation
AC&SC = full ROM
joint stabilization

83
Q

ratio of peak isokinetic torques for medial/lateral rotators:

A

3:2
(pecs, teres major, subscapularis) : (infraspinatus, teres minor)

84
Q

ratio of peak isokinetic torques for adductors to abductors:

A

2:1
(lat dorsi, teres major, pec major) : (deltoid, supraspinatus)

85
Q

ratio of peak isokinetic torques for extensors to flexors:

A

5:4

86
Q

what muscles might cause functional deficiency?

A

serratus anterior
- limit upward scap rotation
- long thoracic nerve palsy?
trapezius
- limit shoulder elevation
- spinal accessory nerve palsy?

87
Q

what is total shoulder motion a result of?

A
  • balance b/n joints
  • functioning and synchronization of muscles