lecture 9: shoulder Flashcards
what is shoulder fucntion
key factor that will orient the upper extremity to the ttrunk
what are the movements possible at the shoulder movement
extension/flexion
adduction/abduction
medial/lateral rotation
circumduction
what is harder to do lateral or medial extension
lateral
what are the bones of the shoulder complex
humerus
scapula
clavicle
(acromion and coracoid process)
what is the shape of the clavicle
crank shaped strut
expain the shape of the clavicle
convex towards sternum (neurovascular structures) / concave towards humerus
what are the function of the clavicle
attaches shoulder to axial skeleton
force transmission to scapula
contributes to ROM
where is the scapula located
between T2-T7
what is the primary fucntion of the scapula
muscle attachment
how do they evaluate internal rotation of the scapula
via distance from T7
the coracoid process is located anterior or lateral
anterior
the acromion process is located anterior or lateral
lateral
what forms the roof over the humerus
acromion
what are the 3 types of the acromion variations (bigliani)
type 1: flat
type 2: slightly curved
type 3: hook shaped
what acromion variation contributes to compression structures
type 3 (hook shaped)
only 25-30% of humeral head is in contact with the fossa, so what is added to increase contact area
labrum
what part of labrun is most vulnerable
superior aspect is vulnerable to tears = slap lesions
(because of bicep insertion)
stability in the shoulder is increased by what in the glenoid fossa
labrun
the superior aspect of the scapula is located to what degrees in the plane
superior aspect is 30-45 anterior to frontal plane
true or false: scapula also has slight anterior inclination and upward rotation
true
true or false: scapula also has slight BLANK inclination and BLANK rotation
slight anterior and upward rotation
where is the radial n located in the humerus
in the spiral/radial groove
what is the inclination of the humeral head
135
what is the angle of torsion of the humerus
30
true or false: the humeral head is in retroversion
true
why is there inclination and torsion of the humerus
so the humeral head can articulate in a continuous manner with the glenoid fossa
what are the 4 joints of the shoulder
acromioclavicular
sternoclavicular
glenohumeral
scapulothoracic
what type of joint is the AC joint
synovial joint
what are the 3 rotatory motion of the AC joint
internal/external rotation
anterior/posterior tipping
upward and downward rotation
what are the 3 translatory motions of the AC joint
anterior/posterior
medial/lateral
superior/inferior
what is the function of the AC
allows additional ROM of the scapula on the thorax and force transmission trhough UE
what are the ligaments of the AC joint
coracoclavicular (trapezoid and conoid)
acromioclavicular lig (surrounded by joint capsule)
what does AC jt limit
limits superior displacement
medial stability during medially directed blow to shoulder is faciliated by what
trapezoid ligament
what is the function of the trapezoid ligament
helps prevent medial displacement of the acromion on clavicle during a medial blow to the shoulder
prevents medial displacement of acromion on clavicle
explain the function of conoid ligament
arm elevation: intially clavicle and scapula in upward rotation together
scapula continues to rotate upwards and CONOID tightens and eventually restricts this motion
clavicle becomes pulled in upwards rotation
as the scapula moves away from the clavicle during arm-trunk elevation, the conoid ligament is pulled taut and causes the clavicle to do what
rotate upwardly
what is a grade 1 AC jt injury
AC ligament stretched of partially torn
what is a grade 2 AC injurty
AC ligament completely torn
what is a grade 3 AC injury
AC jt seperation, tear of AC and coracoclavicular ligament and capsule
what type of joint is the sternoclavicular jt
synovial joint
what are the 3 rotary motions of the SC joint
elevation and depression
protraction and retraction
anterior and posterior rotation
what are the 3 translatory motions
anterior/posterior
medial/lateral
superior/inferior
what is the function of the SC
connects upper limb and axial skeleton
what are the ligaments of the SC joint
anterior/posterior sternoclavicular
interclavicular
costcoclavicular
intraarticular disk
where is the anterior/posterior sternoclav lig located
1st rib and clavicle
what ist eh function of the interclavicular lig
limits lateral movement
what is the function of the intrarticular disk of the SC joint
shock absorb
what jt moves opposite to the SC joint
AC
rotation of the SC joint about an axis causes the head and opposite end of clavicle to move in same or opposite directions
opposite (see saw)
shoulder elevation-depression is aka
shoulder shrug
what is the movement (degrees) in elevation of the SC jt
50
what is the movement (degrees) in depression of the SC jt
10
what is the movement of clavicle at SC joint
elevation
depression
upward/downward slide
what is protraction of the shoulder
lateral end of clavicle and scapula move away from rib cage and scapular abduction
what is retraction of the shoulder
lateral end of the clavicle and scapula move psoteriorly and scapular adduction
what is the degrees of sternoclavicular ROM in protraction and retraction
30-60 degrees
true or false: in the scapulathoracic joint there are true articulations
false, there are none
what are the 2 translateion of the scapulothoracic jpint
elevation and depression
abduction-adduction
what are the 3 rotation movements of the scapulothoracic jt
upward-downward rotation
internal-external rotation
scapular tilt
explain upward rotation of the scapula
glenoid fossa moves in superior direction
explain downward rotation of the scapula
glenoid fossa moves in inferior direciton
what is the total upward/downward ROM of the scpula
60
true or false: upward rotation of the shoulder depends only on scapula
false, upward rotation also relies on clavicular elevation and posterior rotation
define anterior scapula tilt
superior border of scapula tips forward
define posterior scapula tilkt
superior border of scapula tips backward
what are the 5 essential functions of the scapulothoracic joint
1) increase ROM of shoulder to enhance reach
2) maintain favourable length-tension relationship for the deltoid to function greater than 90
3) maintain G-H stability for overhead work
4) shock absorption
5) permits elevation of body (ex: push up)
what type of jt is the glenohumeral joint
ball and socket
how many degrees of freedom are in GH joint
3 degrees of freedom
true or false the GH joint has poor stability despite GH ligaments
true
the capsule of the GH joint is large and loose inferiorly or superiorly
inferiorly (adhesive capsulitis)
what is the close packed position of the GH joint
adbctuon and external rotation
what is the ration of scapulohumeral ryhtm and arm elevation
2:1 (for every 2 degrees of GH joint there is 1 degree of scapulothoracic)
in 180 arc of movement, if the GH joint moves 120 degrees, how much does the ST joint move
60 degrees
what is the movement of scapula during scapulohumral rhytm and arm elevation
posterior tilt, upward rotation, external rotation
what is the movement of humerus during scapulohumral rhytm and arm elevation
anterior flexion and abduction
what are the shoulder joints and therir total contribution to the 180 arm elevation
GH: 120 abduction
ST: 60 upward rotation
SC: 30 elevation
SC_ rotates postiior
AC: upward rotation 30 degrees
what are some examples of static glenohumeral stability
coracohumeral lig
glenohumeral ligs
labrum
capsule
joint contact
scapular inclination
intraarticular pressure
what are the dynamic stabilizers of the shoulder
rotator cuff muscles
biceps
deltoid
what is the test for inferior instability of the shoulder joint
sulcus sign
what is the test for anterior instability
apprehension sign
what are the shoulder instability classifications
etiology (traumatic vs atruamatic)
degree of instability (subluxation vs dislocation)
unidirectional vs multidirectional
general ligamentous laxity
what forms the coracoacromial arch
coracoacrominal lig
what space lies uner the coracoacromial lig
sub-acromial space
what forms the roof of the glenohumeral joint
coracoacromial arch
what forms the floor of the GH joint
head of the humerus
when does the coracoacromial arch narrow
with elevation and internal rotation
what is locatied in the subacromial space
supraspinatus and bursa
and long head tendon of biceps
what is shoulder impingement
irritation of structures in the subacromial space
what normally gets impinged in the subacromial space
supraspinatus and long head of the biceps
true or false: impingement must always be sutained
false, sustained and intermittent compression
impingement of shoulder is narrowing of what
subacromial space
subacromial space reduction can be caused by both intrisina nd extrinsic mechanisms?
true
what is an example of an intrinsic mechanism for subacromial space reduction
factors within tendon (cuff degeneration)
what are some examples of an extrinsic mechanism for subacromial space reduction
glenohumeral kinematics
anatomical/boney factors
scapular kinematics
allignment
ergonomic/sports factors
give an example of a sport that causes impingement and give the reasoning
butterfly swimming
because repetitive internal rotation and abduction (narrows subacromial space)
what are the 2 tests for impingements
neers test
hawkins test
what is the neers test
for impingement
full forward flexion and internally rotates
what is the hawkins test
for impingement
forward flexion (but only at 90 degrees) and bring into internal rotation
true or false: rotator cuff tears can only be traumatic
false, both wear and tear and also traumatic
what muscles are glenohumeral stabilizers
supraspinatus
infraspinatus
teres minor
subscapularis
biceps
deltoid
the deltoid causes the humerus and humeral head to translate where
superiorly
true or false: the deltoid alone can independantely fully abduct (elevate) the arm
false
what does the supraspinatus do for glenohumeral stabilization
abduction of the humerus and compression of the humeral head
what is the function of the infraspinatus, subscapularis, teres minor for GH stability
initially pull humeral head downwards and then externally rotate humerus (positioning of greater tubercle)
all muscles work to compress humeral head in glenoid fossa during arm elevation
what muscles “force couple: with deltoid
infra, subscap and teres minor
the upwards pull of the deltooid is balanced by what muscles
by the downward pull of the inspraspinatus, teres minor, and subscapularis muscles
what muscles are scapular stabilizers
serratus anterior
trapezius
rhomboids
pectoralis minor
levator scapula
wjat is the force couple for the scapula for upward scapular rotation
for upward scapular rotation
upper/lower trapezius and serratus anterior
(maintains tension)
what is medial winging of the scapula caused by
serratus anterior weakness/long thoracic nerver
(trapezius overpulling)
what is lateral winging caused by
trapezial weakness/spinal accessory nerve
(serratus overpulling)
injury to the long thoracic n or serratus anterior weakness will cause medial or lateral winging
medial
injury to the spinal accessory n or trapezial weakness will cause medial or lateral winging
lateral
wjat is the force couple for the scapula for downward scapular rotation
pectoralis minor
levator scap
rhomboids
what are the large muscle movers of the shoulder
lat dorsi
teres major
pectoralis major
coracobrachialis
shoulder depression/weight bearing is caused by what muscle
latissiumus dorsi/pec major
when is compressive load on the joint highest of the shoulder
at 90
when is abductor muscle force highest of the shoulder
at 90
which ligament helps AC joint stabilization with a medially directed foreces
trapezoid
the moment arm of the weight of the upper extremity is largest at what degree
90
what will you see if there is no rotator cuff function
difficulty abduction
humeral head displacing too far superiorly (leads to impingement)
