Shoulder Joint Flashcards
function of shoulder
position the UE (hand) for function
shoulder is more dependent on ________ than on ________ for integrity
muscle;
joint structures;
mobility to permit UE function but at a cost
most likely joint of UE to dislocate
scapulothoracic joint is not a true anatomical joint because
there is no fibrous union
no capsule
it is still considered a joint tho
supra-acromial
coracoacromial arch & the head of the humerus
movement of the Scapulothroacic joint is associated with movement of ______ & ________
Acromioclavicular & sternoclavicular
common lever of the shoulder
clavicle
scapulothoracic joint
- is not a true anatomical joint
- associated with acromioclavicular & sternoclavicular
common link of the scapothoracic joint
clavicle
functions of the scapulothoracic joint
- maintain optimal position of glenoid fossa
- incr functional ROM of upper extremity
- provides a stable base for upper extremity function
scapulothoracic joint primary motions
elevation/depression – translatory
(this is an up & down motion – i.e. shrug shoulders)
abduction/adduction (protraction/retraction) – translatory
upward/downward mobility – rotary
scapulothoracic joint secondary motions
tipping & winging
winging (scapulothoracic secondary motion)
rotation about vertical axis (vertebral axis comes away)
caused by weak serratus anterior
tipping (scapulothoracic secondary motion)
rotation about medial-lateral axis
scapulothoracic joint – function of secondary motion
maintain proximity of scapula on thorax
stabilization of scapulothoracic joint
muscles & atmospheric pressure
when you have _____ movement there will be _____ movement
scapula;
clavical
and vice versa
structural attachment between the axial & appendicular skeleton
sternoclavicular joint
anterior & posterior sternoclavicular ligaments check:
anterior & posterior motion of clavicle
costoclavicular ligament
primary stabilizer
- site of AOR for elevation/depression & protraction/retraction
- checks elevation & superior glide of clavicle
- movement is limited upward
interclavicular ligament checks
checks depression & downward glide
sternoclavicular elevation ROM
45 deg
sternoclavicular depression ROM
15 deg
sternoclavicular protraction ROM
15 deg
sternoclavicular retraction ROM
15 deg
rotation ROM
30 - 45 deg
arthrokinematics sternoclavicular joint
rotation posteriorly
sternoclavicular joint disk
- increases joint surface congruency
- acts as a hinge/pivot point
- absorbs forces from appendicular skeleton (extremities)
depending on the motion the sternoclavicular joint disk will be stuck on either the ______ or _______
manubrium;
clavicle
then the bone without the disk will move on that
acromioclavicular joint is _____ lateral clavicle on _____ acromion
convex;
concave
acromioclavicular joint allows for increased
increased scapular motion
acromioclavicular joint allows for adjustment of the
scapula outside of the initial planes of motion
acromioclavicular joint transmits:
forces from the scapula to the clavicle
acromioclavicular joint anatomy
fibrocartilage disk that degenerates with time
weak capsule
superior & inferior acromioclavicular ligaments
- check horizontal movements
- relatively weak
coracoclavicular ligaments - medial
conoid
coracoclavicular ligament - lateral
trapezoid
coracoclavicular ligament checks
primarily superior dislocation of the clavicle * important
coracoclavicular ligament
limits & assists scapula movement
acromioclavicular joint
susceptible to trauma (dislocation) & degenerative changes
acromioclavicular separation
tearing of the coracoclavicular ligament
–> this lets the clavicle go up and then the Acromioclavicular ligament tears
labrum
(at glenohumeral)
- redundant fold of dense fibrous connective tissue continuous with capsule
- increase joint congruency
capsule of glenhumeral joint
- taut superiorly
- loose anteriorly < inferiorly
- risk of dislocation: anterior > inferior > posterior > superior
greatest risk of dislocation (GH joint capsule)
anterior capsule of glenohumeral joint
least risk of dislocation (GH joint capsule)
superior capsule of GH joint
GH joint ligaments
thickening of anterior capsule
3 ligaments – superior, middle, inferior
GH joint ligaments - all tighten with _______ and ______ of humeral head – although not ___________
ER;
anterior translation;
overly strong
Coracohumeral ligament location
coracoid process –> blends with superior capsule & supraspinatus tendon –> greater tubercle
Coracohumeral ligament checks
checks external rotation and inferior translation of humeral head
bursa of GH joint
subacromial – can be 2 distinct bursa (subacromial & sub deltoid)
–> common site of pain
function of bursa
prevent friction at tendon
bursitis
synovial filled sac (bursa) is swollen
coracoacromial (suprahumeral arch)
- osteoligamentus ceiling of GH joint
- subacromial bursa lies between it and the humeral head
- region of pain secondary to impingement
coracoacromial (suprahumeral arch) prevents
the humeral head from dislocating superiorly
angle of inclination (GH joint)
- frontal plane
- occurs between long axis of shaft & humeral head
- norm= 130 - 150
glenoid fossa faces
anteriorly and inferiorly
humeral head faces
medially, superiorly, & posteriorly
angle of torsion (GH joint)
- transverse plane
- between humeral condyles & humeral head
- NORM: 30 deg posteriorly
how many degrees of freedom of osteokinematics of glenohumeral joint?
3 DOF
flexion/extension of GH joint
100-150 deg
abduction of GH joint ROM
60 deg medially rotated
adduction of GH joint ROM
90 - 135 deg
internal rotation of GH joint ROM
50 deg adducted
external rotation of GH joint ROM
120 deg (abducted to 90)
scaption of GH joint ROM
90 - 120 deg (scaption = elevation in plane of scapula)
never get pure spin of GH joint due to
arthrokinematics
non-congruence
GH joint arthrokinematics
- non-congruent causes never a pure spin
- associated with gliding & rolling
- follows convex & concave rule
around the labrum is ______ congruency
increased
moving concave and whole structure moves in _____
same direction (stabile convex)
stable concave and structure moves in
opposite direction (moving convex)
arm at side (dependent position) is
the superior joint capsule & coracohumeral ligament
–> keeps joint in approximation when in normal rest state
supraspinatus becomes active with:
heavier loads
muscle function of dynamic stabilization – GH joint
- move the humerus
- provide intra-articular gliding
- maintain apposition of joint (good approximation because of strong muscles and support)
dynamic stabilization – abduction
deltoid & supraspinatus
dynamic stabilization – flexion
anterior deltoid (mainly translatory)
unopposed deltoid activity
- impaction of the humeral head in the coracoacromial arch
- rotator cuff is the opposing force (specifically: infraspinatus, subscapularis, trees minor)
Rotator cuff muscles
supraspinatus, infraspinatus, teres minor & subscapularis
- blends w/ and reinforces joint capsule
infraspinatus, subscapularis & Teres minor synergists with ________ to allow for _______
deltoid;
elevation
ROTATOR CUFF FUNCTION
ROTATOR CUFF FUNCTION – forces both ____ & ______
rotary & compressive
(dynamic stability)
ROTATOR CUFF FUNCTION
teres minor & infraspinatus _________ rotate the humerus to clear the ________ during ________
externally;
greater tubercle;
elevation
ROTATOR CUFF FUNCTION
compressive component of supraspinatus
stabilizes GH joint
ROTATOR CUFF FUNCTION
supraspinatus is a _____ translator force
superior
ROTATOR CUFF FUNCTION
rotary component of supraspinatus
significant abductor
ROTATOR CUFF FUNCTION
predispositions to dislocations at the rotator cuff
- anterior tilt of glenoid fossa
- excessive retrotorsion
- weakened rotator cuff
biceps tendon (@ rotator cuff)
supraglenoid tubercle –> ulna
- long head reinforces the anterior glenohumeral joint
- wearing of bicipital tendon sheath transverse humeral ligament
- poorly vascularized
scapulohumeral rhythm
180 deg = 120 glenhumeral joint movement + 60 deg scapulothoracic joint
ratio of scapulohumeral ryhthm
Glenohumeral:Scapulothoracic = 2:1
over the entire range
for every 2 degrees of GH you get 1 deg of scapula movement
Scapulohumeral rhythm for pre-phase/setting:
Inconsistent amount of scapula movement causes
proximal stability for distal mobility
Scapulohumeral rhythm pre-phase/setting:
G-H movement
60 degrees flexion and
30 degrees abduction
TOTAL= 30 - 60 degrees all G-H motion
Scapulohumeral rhythm: phase I & Scapulothoracic motion
muscle movement
Trapezius (upper & lower) & serratus anterior (upper & lower) contract
Scapulohumeral rhythm: phase I & Scapulothoracic motion
ligament movement
coracoclavicular ligament tightens locks AC joint
because the AC joint is locked down the scapula & clavicle can move together
Scapulohumeral rhythm: phase I & Scapulothoracic motion
clavicle motion
clavicle elevates about 30 degrees through sternoclavicular joint
Scapulohumeral rhythm: phase I & Scapulothoracic motion
scapula movement
tipping & 10 degrees of winging
The scapula and clavicle move together because the AC joint is locked down
Scapulohumeral rhythm: phase II & acromioclavicular motion
ligament motion
- costoclavicular ligament tightens
- the taut costoclavicular ligament pulls down on the coracoid
- this pulls the conoid tubercle of the clavicle down
Scapulohumeral rhythm: phase II & acromioclavicular motion
movement of the clavicle
rotation of clavicle on long axis
Scapulohumeral rhythm: phase II & acromioclavicular motion
movement of the scapula
rotation of the scapula on axis through acromioclavicular joint
20 degrees tipping & 40 degrees winging
scapulohumeral rhythm summary 0 to 90 degrees incr
60 deg glenohumeral, 30 degrees scapulothoracic about sternoclavicular joint
scapulohumeral rhythm summary 90 to 180 degrees incr
60 deg glenohumeral, 30 degrees scapulothoracic about acromioclavicular joint
The significance of sternoclavicular and acromioclavicular motion
for clavicle to rotate about its longitudinal axis
Scapulohumeral rhythm function
- distribute large ROM between 2 joints, less compromise of stability
- maintain optimal position of glenoid fossa
- maintain optimal length-tension relationship for muscles
Deltoid
- middle deltoid abducts
- maintenance of optimal length-tension is dependent on scapula motion
- Rotator cuff (oblique - infraspinatus, subscapularis, trees minor): combines with deltoid to form a force couple
Supraspinatus motions
- Major abductor and flexor (prepares glenohumeral joint for shoulder flexion) - during abduction pulls humerus head into shoulder joint
- begins glenohumeral joint through full ROM without deltoid
Supraspinatus functions
- Primary mover for abuction and flexion
- Compresses G-H joint
- Steers humeral head vertically
Infraspinatus & teres minor
external rotation
- compresses & stabilizes
subscapularis
internal rotation
- compresses and stabilizes
Two force couples - muscle function
- upper segments of traps and serratus anterior along with levator scapula
- lower segments of traps and serratus anterior
force couples
pull in different directions but produce the same movement
downward rotation of shoulder (force couples)
- pec minor = pull down
- levator scapulae = pull up
- latissimus dorsi = pull down
upward rotation of shoulder (force couples)
- lower traps = pull down
- upper traps = pull up
- serratus anterior = pulls up from forward
function of latissimus dorsi
- adduction, medial rotation, extension of humerus
- adduction and depression of scapula
- seated push ups & crutch walking (holds scap down in place when you push your body upward)
function of pectorals major
- clavicular head - flex glenohumeral joint
- sternal portion parallels the latissimus to depress the shoulder complex
function of pectorals minor
- depress and rotates scapula downward
function of trees major
- adduction, medial rotation, extension of humerus
latts helper~~
Total elevation in pre-phase G-H joint
30 - 60 degrees
Total elevation in phase I
- 30 degrees of S-T rotation & clavicular elevation
- 30 degrees of G-H movement
total elevation in phase II
- 30 degrees of S-T rotation & AOR through AC joint
- 30 to 60 degrees of G-H joint movement
Total elevation of the shoulder joint
180 degrees
