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DPT 702: Biomechanics > Lecture 9: arthrology of the shoulder Test 3 > Flashcards

Lecture 9: arthrology of the shoulder Test 3 Flashcards

1
Q

articulations of the shoulder complex

A

Sternoclavicula = clavicle strut holding scapula

Acromioclavicular = firmly attaches the scapula to clavicle

scapulothoracic = not a true joint; interface between bones; movements linked to AC/SC; position of scam provides base for GH

glenohumeral = most distal and mobile portion of complex

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2
Q

describe the shoulder complex

A

series of kinematic links

cooperate to maximize ROM

weakened/painful or unstable link decreases the effectiveness of entire UE

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3
Q

how does the scapula move with elevation/depression

A

superior and inferior glide respectively

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4
Q

how does the scapula move with protraction and retraction

A

medial border slides ant/lateral with protraction

retraction = posterior medial

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5
Q

how does the scapula move with upward rotation

A

inferior angle rotates superior lateral direction, glenoid fossa faces upward = UE elevation

downward rotation = inferior angle rotates inferior medial direction with UE lowering

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6
Q

what articulates at the SC joint

A

medial end of clavicle with clavicular facet on sternum

superior border of the cartilage of the 1st rib

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7
Q

what is the basilar joint of the UE

A

SC joint

links axial to appendicular skeleton

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8
Q

characteristics of SC joint

A

extensive periarticular tissues

irregular saddle shaped

convex and concave with sternal facet reciprocally shaped

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9
Q

where are the longitudinal diameters of the SC joint

A

extend roughly in the frontal plane between superior and inferior points of articular surfaces

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10
Q

what are the transverse diameters of the SC joints

A

extend roughly in the horizontal plane between anterior and posterior points of the articular surfaces

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11
Q

periarticular tissues of the SC joint (i.e what are the structures like muscles, ligaments, etc around the joint)

A

anterior and posterior SC ligaments (reinforce capsules)

interclavicualr ligament

costoclavicular ligament

articular disc (only 50% of people)

SCM, sternothyroid, sternohyoid, and subclavis muscles

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12
Q

movement at the SC joint

A

3 degrees of freedom (sagittal, frontal, and horizontal)

elevates/depresses, protracts/retracts, and rotates

goal = place scapula in optimal position for head of humerus

all movements of the GH joint involve some movement at SC

clavicle rotates in all 3 degrees of freedom with UE elevation

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13
Q

osteokinematics of elevation and depression of clavicle

A

generally parallel to frontal plane

axis is near anterior posterior

35-45 degrees elevation

10 degrees depression

clavicular motion produces similar in scapula

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14
Q

arthrokinematics of elevation and depression of the clavicle

A

occur along the longitudinal diameter

elevation = convex surface rolls superiorly and glides inferiorly; CC ligament stretches and limits motion

depression: convex surface rolls inferiorly and slides superiorly; intraclavicular ligament/superior portion of the capsule stretches

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15
Q

osteokinematics of protraction and retraction of the clavicle

A

occurs neatly parallel to horizontal plane

axis = vertical

15-30 degrees each direction

associated with scapular retraction/protraction

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16
Q

arthrokinematics of the clavicle with protraction and retraction

A

occurs along SC joints transverse diameter

retraction = concave surface of clavicle rolls and slides posteriorly on convex surface of sternum; stretches anterior CC ligament and anterior capsule

protraction = occurs in an anterior direction; stretches posterior CC ligament and posterior capsule, involved in reaching forward

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17
Q

osteokinematics of rotation of the clavicle

A

around the bones longitudinal axis

UE elevation: posterior rotation 20-35 degrees (point on superior clavicle)

as UE returns, clavicle returns

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18
Q

arthrokinematics of the clavicle with rotation

A

spin of its sternal end relative to the lateral surface of the articular disc

axial rotation is linked with the overall kinematics of flexion and abduction (can’t be performed with the arm resting at the side)

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19
Q

what are the articulations for the acromioclavicular joint

A

lateral end of clavicle and acromion of scapula

clavicular facet on the acromion faces medial and slightly superior

articular disc of varying form is present in most AC joints

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20
Q

periarticular tissues of the AC joint

A

capsule is directly reinforced by superior and inferior AC ligaments

coracoclavicular ligament (extrinsic stability for AC)

2 parts of coracoclavicualr ligament = trapezoid ligament and conoid ligament (go from the coracoid process to the clavicle)

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21
Q

describe the kinematics of the AC joint

A

subtle movements between scapula and lateral clavicle

optimizes mobility and fit between scapula and thorax

motions are described scapula relative to the clavicle

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22
Q

movements present at the AC joint

A

3degrees of freedom

up/downward rotation

secondary motions = rotational adjustment motions; to fine tune position of scapula (horz and sagittal plane)

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23
Q

describe upward rotation of the scapula at the AC joint

A

swings upward and out relative to the end of clavicle with upward rotation

natural motion as part of elevation

up to 30 degrees

contributes significantly to scapulothoracic motion

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24
Q

describe downward rotation of the scapula at the AC joint

A

scapula rotates around clavicle to return to anatomical position

it looks like frontal plane but really is is the scapular plane

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25
what are rotational adjustment motions at the AC joint
pivoting or twisting type motions of the scapula around the lateral end of the clavicle optimally align the scapula against the thorax horizontal plane: vertical axis; medial border moves away (IR of glenoid fossa) sagittal plane: medial-lateral axis; inferior angle pivots away (anterior tilt) or reverse (posterior tilt)
26
kinematics of AC joint with protraction
AC joint IR in the horizontal plane helps align the anterior surcease of the scapula with the thorax curved surface
27
kinematics of AC with elevation of scapula
"shrugging" is accompanied by anterior tilt
28
what would happen if there were no scapular adjustments with movements
the scapula would have to follow the clavicle exactly and could not adjust to the thorax
29
describe the scapulothoracic joint
not a true joint: no direct contact, but separated by layers of muscles scapula is seated between 2nd and 7th ribs; medial border 6 cm lateral to spine
30
motions of the scapulothoracic joint
large UE ROM largely dependent on scapular motion 10 degrees anterior tilt 5-10 degrees upward rotation 30-40 degrees internal rotation
31
muscles that separate the scapulothoracic joint
subscapularis serratus anterior erector spinae
32
describe elevation/depression at the scapulothoracic joint
composite SC and AC scapulothoracic elevation is a summation of elevation at SC and downward RT at the AC joint
33
how can you describe protraction/retraction at the scapulothoracic joint
summation of horizontal motions at SC and AC protracting the clavicle around SC joint; varies with the amount of IR
34
describe upward/downward RT at the scapulothoracic joint
integral part of UE elevation places the glenoid fossa in a position to support/stabilize the head of the humerus summation of clavicular elevation and SC/scapular upward RT full 60 degrees of upward RT
35
describe the kinematics of scapulothoracic upward rotation
summation of elevation at the SC joint and upward RT at the AC joint
36
general features of the glenohumeral joint
large convex head shallow concavity = glenoid fossa head positioned medially, superiorly, and posteriorly (normal retroversion)
37
in anatomical position describe the inferior portion of the capsule of the shoulder
slackened called axillary pouch
38
what lines the inner wall of the GH joint
synovial membrane
39
head of humerus and glenoid fossa are lined with
articular cartilage
40
potential volume of space in GH joint
2x size of the humeral head
41
primary stabilizers of GH joint
passive tension with embedded ligaments active forces produced by local muscles (specifically rotator cuffs) LHB crosses superiorly over the head of the humerus
42
function of the capsular ligaments of the GH joint
limites extremes of RT and translation help keep a negative intra-articualr pressure in GH joint
43
describe the makeup of capsular ligaments
fibrous connective tissue interlacing collagen fibers thickening of capsule in complex bands
44
function of superior capsular ligament
resists ER/inferior and anterior translations
45
function of the middle capsular ligament
stabilizes most motions especially restraint in 45-90 abduction and extremes of ER slack in IR blends with subscap
46
function of the inferior band of capsular ligament
3 portions taught in 90 degree abd hammock like supports the suspended humeral head resists inferior/anterior-posterior translation
47
what is the strongest portion of the capsule
anterior is the strongest/thickest portion of the capsule primary ligamentous restraint to anterior translation (abd and neutral) ABD and ER forceful dynamic activities are especially stressful
48
coracohumeral ligament: where does it attach, when is it taught, what does it blend with, and what does it restrict
from the coracoid process to the greater tubercle blends with the superior capsule and supraspinatus tendon taut in anatomical position restraint inferior translation and ER humeral head
49
significance of the rotator cuffs
significant structural support to the capsule blends with capsule belly of muscles close to the joint protects and acts as an active stabilizer
50
4 rotator cuff muscles
subscapularis = thickest/anterior to capsule supraspinatus, infraspinatus, and teres minor = posterior to the capsule
51
regions of vulnerability for rotator cuff muscles
rotator interval: triangular space formed by the tendons of subscapularis and supraspinatus and the coracoid process common site for dislocation reinforced by LHB, coracohumeral ligament, and sup/mid capsular ligaments
52
origin of the LHB
supraglenoid tubercle and labrum , intracapsular tendon crossed the humeral head, inter tubercle groove on anterior humerus
53
LHB resists whats
restricts anterior translation of the humeral head the force generated through the tendon across the dome of the humeral head resists anterior translation - needed in ABD
54
describe the glenoid labrum
fibrocartilaginous ring 50% depth is from this structure stabilizer
55
tissues that reinforce/deepen the GH joint
joint capsule/GH ligaments coracohumeral ligament rotator cuff muscles LHB glenoid labrum
56
describe the static stability of the GH joint
at rest the humerus is stable on the glenoid fossa like a ball on an inclined surface superior capsular structures (superior capsular ligament, CH ligament, and tendon of supraspinatus) there is a resultant compressive force
57
describe the forces of the rotator cuff and significance
RC has horizontal forces to help if there is a load added to the arm muscular forces act as a rope that holds the scapula in position of the slightly upward fossa disruption can cause humeral head to drift inferiorly due to plastic deformation of SCS = subluxation or dislocation
58
what is the coracoacromial arch
formed by the coracoacromial ligament and acromion process roof of the GH joint creates subacromial space between the arch and the humeral head average of 1 cm in adults with arm at rest by side
59
what does the coracoacromial arch contain
supraspinatus muscle and tendon subacromial bursa (direct extension of synovial membrane of the GH joint) LHB superior capsule
60
where are the bursa of the GH joint
situated where significant frictionless forces develop such as between tendons, capsules and bones, muscles and ligaments, or 2 adj muscles
61
what 2 bursa are superior to the humeral head
subacromial bursa (above SS) = protects SS from acromial bone sub deltoid bursa = limitse friction forces between the deltoid and the SS tendon/humeral head
62
kinematics of the GH joint
3 degrees of freedom 4th motion defined: horizontal abd/add (starts at 90 degrees abd - vertical axis) anatomic position = 0 degrees
63
describe abd/add of the GH joint
ABD: rotation of humerus in frontal plane; AP axis 120 degrees NLs at GH joint simultaneous 60 degrees upward scapular rotation convex head of humerus rolls superiorly, slides inferiorly larger head does not roll of due to this sliding ***add is reverse***
64
describe dynamic stability of the GH joint
part of the SS tending blends with superior capsule active contraction pulls the capsule tight and prevents it from being pinched between the humeral head and the undersurface of the acromion at 90 deg ABD humeral head stretches ICL (axillary pouch) which acts like a hammock supporting the head of the humerus
65
describe the height of the subacromial space and the significance
impacted bu GH arthrokinematics and scapular motion critical minimum must be maintained for lack of compression of contents in the space: 7.5 mm at 20 deg ABD 2.6 mm at 85 deg ABD 5mm at 150 deg ABD
66
clinical significance of the arch representing the subacromial space
arc is where SS potential compression is at 35-70 deg
67
what is adhesive capsulitis
excessive thickening or stiffness in ICL limits inferior slide of humeral head superior roll leads to jamming of the humeral head against the coracoacromial arch
68
what is impingement syndrome
unnatural and repeated compression/abrasion may damage the SS tendon, subacromial bursa, LHB tendon, or superior parts of the capsule over time repeated compression may lead to this syndrome
69
arthrokinematics of humerus with flex/ext
arthro = spinning motion of humeral head in fossa
70
describe the surrounding structures of the GH joint with flexion and extension
most surrounding structures are taut tension in posterior capsule may cause slight anterior translation of humerus in extremes of flexion
71
how much range of flexion and extension is present in the shoulder with flexion and extension
120 degrees GH flexion/180 includes scapula extension = 65 degrees active, 80 passive
72
how does the scapula move with flexion and extension of the shoulder
slight anterior tilt of the scapula, stretch of capsular ligaments
73
how does the humerus move with ER of the shoulder
axial rotation o the humerus in the horizontal plane
74
ER/IR ROM present in shoulder
75-85 degrees IR 60-70 degrees ER with ABD of 90 degrees, ER of up to 90 (variable) neutral = in IR?
75
roll/slide of humerus with ER
ER rolls posteriorly and slides anteriorly reverse for IR
76
describe the principle of scapulohumeral rhythm
natural coupling of GH ABD and Scapulothoracic Upward RT after 30 degrees of ABD, rhythm is consistent ratio = 2:1; for every 3 deg of ABD there are 2 deg at the GH joint and 1 deg at the ST upward RT full arch of 180 degree movement = 120 at GH and 60 at ST
77
describe the ST and SC joints during full abduction
60 degrees of movement at the ST joint is a combo of elevation at SC joint and upward RT at AC SC joint elevates 30 deg during the 180 arch
78
how does the clavicle move at the SC joint during ABD
clavicle retracts starts at 20 deg posterior to the frontal plane retracts another 15-20 degrees with ABD
79
describe the tilt of the scapula with ABD and what these movements help with
as full abd occurs, the scapula tilts posteriorly and slightly rotates outward at rest = anterior tilt of 10 degrees, IR 30-40 deg with ABD it posteriorly tilts 20 deg these movements help keep the scapula flush with the thorax, orients the fossa, and moves the coracoacromial arch away from the advancing humeral head
80
describe the rotation of the clavicle with ABD
rotates posteriorly along its own axis 20-35 degrees during full ABD those with subacromial impingement showed reduced RT
81
describe the movement of the humerus with ABD
naturally ER with ABD allows greater tubercle to pass posterior to the acromion 25-50 degree range; majority occurs before 70-80 degrees of ABD

DPT 702: Biomechanics (13 decks)

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