Exam #3 (Lecture 10; Joints-Coracoacromial arch) Flashcards
clavicle like a strut holding the scapula:
Sternoclavicular
firmly attaches the scapula to clavicle:
acromioclavicular
not a true anatomic joint
an interface between bones
movements are linked to the movements at the SC and AC
the position of the scapula provides the base for the GH joint
scapulothoracic
most distal and mobile portion of the whole complex
glenohumeral
what are 3 features of the shoulder complex? (3)
series of kinematic links
cooperate to maximize ROM
weakened, painful or unstable link decreases the effectiveness of the entire UE
elevation: _______ slide
depression: ________ slide
superior
inferior
protraction: medial border slides _______
retraction: medial border slides _________
ant/lat
post/med
upward rotation: inferior angle rotates _______ direction. glenoid fossa faces _______. UE ________
downward rotation: inferior angle rotates ________ direction. UE ________
superior-lateral direction. upward. elevation
inferior-medial direction. downward
what 3 things connect at the SC joint?
medial end of clavicle
clavicular facet on sternum
superior border of cartilage of the first rib
what links the axial and appendicular skelton?
basilar joint of UE (base of clavicle)
the SC joint is ____ attached and allows _____ ROM
firmly
large
what is the shape of the SC joint?
irregular saddle shaped
longitudinal diameters:
_____ plane between _______ & _______ points
frontal plane
superior and inferior points
transverse diameters:
______ plane between _______ & _______ points
horizontal plane
anterior and posterior points
what ligaments attach at the SC joint?
anterior and posterior SC ligaments (reinforces capsule)
interclavicle ligament
costoclavicular ligament
articular disc (50% only)
what muscles cross across the SC joint?
SCM
sternothyroid
sternohyoid
subclavius muscles
how many DOF for SC joint?
what are the 3 kinematic motions of SC joint?
3 - sagittal, frontal, horizontal
elevates/depresses, protracts/retracts, rotates (posterior)
what is the goal of the SC joint?
to place scapula in optimal position for head of humerus
elevation and depression osteokinematics of SC joint:
parallel to _______ plane
axis -
______ degrees elevation
______ degrees degression
_______ motion is similar in scapula
frontal
near anterior-posterior
35-45
10
clavicular
elevation and depression arthrokinematics of SC joint:
along _____ diameter
elevation of clavicle:
- convex surface rolls _____ slides _____
- ______ ligament stretches - limits motion
depression of clavicle:
- convex surface rolls ______ slides ________
- _______ ligament/_______ portion of capsule stretches
longitudinal
superiorly; inferiorly
Costoclavicular
inferiorly; superiorly
interclavicular; superior
protraction and retraction osteokinematics of SC joint:
occurs parallel to _____ plane
axis:
_______ degrees each direction
associated with _______
horizontal
vertical
15-30
scapula
protraction and retraction arthrokinematics of SC joint:
occurs along _______ diameter
retraction:
- concave surface of clavicle rolls and slides ______ on convex surface of sternum
- stretches ________ ligament and ______ capsule
protraction:
occurs in _____ direction
stretches ________ ligament and ____ capsule
involves reaching ______
transverse
posteriorly
anterior CC ligament and anterior
anterior
posterior CC ligament and posterior
forward
rotation osteokinematics of SC joint:
rotates around _____ axis
UE elevation: posterior rotation ______ degrees
longitudinal
20-35
rotation arthrokinematics of SC joint:
rotation cannot occur without ______ and ______
flexion and abduction
what two things connect at AC joint?
lateral end of clavicle
acromion of scapula
what direction does the clavicular facet face on the acromion?
medial and slightly superior
what is the capsule of AC joint reinforced by?
superior and inferior AC ligaments
what two ligaments make up the coracoclavicular ligament?
trapezoid ligament
conoid ligament
- coracoid process to clavicle
what type of motion happens at the AC joint?
subtle motions
optimize mobility and fit between scap and thorax
how many DOF does AC joint have?
3
upward/downward rotation, internal/external rotation, anterior/posterior tilting
upward rotation of scapula at AC:
swings ____ and _______ relative to end of clavicle
up to _____ degrees
contributes significantly to _______ motion
upward and outward
30
scapulothoracic
what are rotational adjustment motions of the AC joint?
pivoting or twisting type motions of the scapula around lateral end of the clavicle
optimally align scapula against the thorax
what motion of the AC joint is happening in the horizontal plane?
what axis is it?
internal rotation (also protraction) of glenoid fossa (and external rotation)
vertical axis
what motion of the AC joint is happening in the sagittal plane?
what axis is it?
anterior tilting (elevation) or reverse: posterior tilting (depression)
medial-lateral axis
what would happen without adjustments of the AC joint?
the scapula would have to follow the clavicle exactly and could not adjust the thorax
what joint is not true joint with no direct contact?
scapulothoracic joint
the scapulothoracic joint is separated by what muscles?
subscapularis
serratus anterior
erector spinae
where does the scapula sit?
between 2nd and 7th ribs
medial border 6 cm lateral to spine
scapulothoracic joint degrees:
- anterior tilt:
- upward rotation:
- internal rotation:
10 degrees
5-10 degrees
30-40 degrees
scapulothoracic elevation is a summation of what?
elevation at the SC joint and downward rotation at AC joint
in order to have protraction/retraction of ST joint, what summation must occur?
summation of horizontal motions at both AC (internal rotation) and SC (protraction)
protracting clavicle around SC joint, SC varies the amount of internal rotation
scapulothoracic upward rotation is a summation of what?
full ____ degrees of upward rotation
elevation at the SC joint
upward rotation at AC joint
60 degrees
general features of what joint?
large convex head, shallow concavity - glenoid fossa
glenohumeral joint
why is the fibrous capsule of the GH joint loose fitting, thin and expandable?
to allow for mobility which is reinforced by external ligaments
what is the axillary pouch in GH joint?
interior portion capsule slackened
what is the primary stability in the GH joint?
active forces produced by?
what crosses superiorly over head of humerus?
passive tendon within embedded ligaments
active forces produced by local muscles specifically rotator cuff
LBB crosses superiorly over head of humerus
- fibrous connective tissue, interlacing collagen fibers
- thickening of capsule, complex bands
- limits extremes of rotation and translation
- help keep a negative intra-articular pressure in GH joint
glenohumeral capsular ligaments
superior GH capsular ligament resists:
resists ER/inferior and anterior translations
what does the middle GH capsular ligament do?
slack in?
blends with?
stabilizes most motions esp anterior restraint in 45-90 abd and extremes of ER
slack in IR
blends with subscap
what does the inferior GH capsular ligament support? resist?
how many portions? taught in?
supports suspended humeral head
resists inf/anterior posterior translations
3 portions (anterior, posterior, axillary pouch), taught in 90 deg abd
hammock like
what is the strongest/thickest portions of the capsule?
primary ligamentous restraint to?
what motions are esp stressful?
anterior
anterior translation
abd and ER with forceful dynamic activities
where is the coracohumeral ligament?
coracoid process to greater tubercle
coracohumeral ligament blends with?
superior capsule and supraspinatus tendon
coracohumeral ligament taut in?
restraint what?
taut in anatomical position
restraint inferior translation and ER humeral head
what forms the coracoacromial arch?
coracoacromial ligament and acromion process
what is under the coracoacromial arch?
subacromial space between arch and humeral head
what does the coracoacromial arch and bursa contain?
supraspinatus muscle and tendon, subacromial bursa, LHB, superior capsule
what impacts the height of subacromial space?
GH arthrokinematics and scapular motion
what must the the critical minimum heights be to maintain a lack of compression of contents in subacromial space at:
- 20 deg abd:
- 85 deg abd:
- 150 deg abd:
7.5 mm
2.6 mm
5 mm
- more space height is needed as you abduct/adduct arm. least amount of space needed is around 90 deg abd
what degree range has the greatest potential for supraspinatus compression?
35-70 deg
what is adhesive capsulitis?
what does it limit?
excessive thickening or stiffness in ICL
limits inferior slide of humeral head
in adhesive capsulitis, a superior roll leads to what?
how many degrees does it roll before any slide happens?
jamming of the humeral head against coracoacromial arch
22 deg
what is impingement syndrome?
abrasion may damage what?
unnatural and repeated compression. repeated compression may lead to this
abrasion may damage the SS tendon, subacromial bursa, LHB tendon or superior parts of capsule
