Shoulder Study guide Flashcards
What type of joint is the sternoclavicular joint?
- saddle joint
- clavicle: Convex longitudinally, concave transverse
- sternum: convex transverse, concave longitudinally
How many degrees of freedom does the SCJ have?
3
- protraction/retraction (transverse plane)
- elevation/depression (frontal plane)
- axial rotation (sagittal plane)
What osteokinematic motions of the arm are associated with each movement of the SCJ?
-protraction/retraction
- elevation/depression
- axial rotation
Describe the arthrokinematics of the clavicle during protraction
clavicle concave
- rolls and slides anterior
Ant. SC ligament: slack
Post. SC ligament: taut
Describe the arthrokinematics of the clavicle during retraction
clavicle concave
- rolls and slides posterior
Ant. SC ligament: taut
Post. SC ligament: slack
costoclavicular ligament: taut
Describe the arthrokinematics of the clavicle during elevation
clavicle convex
- rolls superior
- slides inferior
costoclavicular: taut
interclavicular: slack
Describe the arthrokinematics of the clavicle during depression
clavicle convex
- rolls inferior
- slides superior
costoclavicular: slack
interclavicular: taut
Which ligaments restrict elevation of the SCJ
- Ant./Post. SC ligaments
- Interclavicular
- Costoclavicular
Which ligaments restrict depression of the SCJ
- Interclavicular ligament
Which ligaments restrict retraction of the SCJ
- Ant./post. SC ligament
- Interclavicular ligament
- Costoclavicular ligament
What type of joint is the acromioclavicular joint?
- gliding/plane joint
follows same movements as scapular motions
What ligaments are associated with the ACJ & what do they do?
Coracoclavicular (conoid & trapezoid)
- suspends the clavicle from the arm
How many degrees of freedom does the ACJ have and what are the planes?
3 degrees of freedom
- upward/downward rotation (frontal plane)
- IR/ER (transverse plane)
- Anterior/posterior tilting (sagittal plane)
What osteokinematic motions are associated with the movement of the ACJ?
- Upward rot: abduction or flexion
- downward rot: adduction or ext from flexion
- IR: protraction of ST joint
- Ant tilt: elevation of ST joint
What is the scapulothoracic joint?
- not actually a joint
- the articulation between the thoracic cage and scapula
What is scaption?
- elevation of the arm within the scapular plane
What is meant by the plane of the scapula?
The resting position of the scapula
- 10 degrees anterior tilt
- 5-10 degrees upward rotation
- 30-40 degrees internal rotation
What occurs at the SCJ & ACJ during scapular elevation
SCJ: clavicle elevation
ACJ: downward rotation
What occurs at the SCJ & ACJ during scapular depression
SCJ: clavicle depression
ACJ: upward rotation
What occurs at the SCJ & ACJ during scapular protraction
SCJ: clavicle protraction
ACJ: AC IR
What occurs at the SCJ & ACJ during scapular retraction
SCJ: clavicle retraction
ACJ: AC ER
What occurs at the SCJ & ACJ during scapular upward rotation
SCJ: clavicle elevation
ACJ: AC upward rotation
What occurs at the SCJ & ACJ during scapular downward rotation
SCJ: clavicle depression
ACJ: AC downward rotation
Which muscles control elevation of the scapula?
- upper trap
- levator scapulae
- rhomboids
Which muscles control depression of the scapula?
- lower trap
- lats
- pec minor
- subclavius
Which muscles control protraction of the scapula?
- serratus anterior
Which muscles control retraction of the scapula?
- middle trap
- lower trap
- rhomboids
Which muscles control upward rotation of the scapula?
- serratus anterior
- upper trap
- lower trap
Which muscles control downward rotation of the scapula?
- levator scapula
- rhomboids
- pec minor
- lats
Which muscles control posterior tilting of the scapula?
- lower trap
- serratus anterior
- middle trap
Which muscles control external rotation of the scapula?
- middle trap
- serratus anterior
- lower trap
What type of joint is the GHJ?
- ball in socket joint
How many degrees of freedom does the GHJ have?
3 degrees
- ER/IR: transverse plane
- Abd/add: frontal plane
- Flex/ext: sagittal plane
*4th motion: horizontal abd/add - vertical AoR
What are the arthrokinematics of the humerus during flex/ext
pure spin
What are the arthrokinematics of the humerus during abduction
humeral head:
- rolls superior
- slides inferior
What are the arthrokinematics of the humerus during adduction
humeral head:
- rolls inferior
- slides superior
What are the arthrokinematics of the humerus during external rotation
humeral head:
- rolls posterior
- slides anterior
What are the arthrokinematics of the humerus during internal rotation
humeral head:
- rolls anterior
- slides posterior
Name the capsular ligaments of the GHJ
- superior glenohumeral
- middle glenohumeral
- inferior glenohumeral
- coracohumeral
What does the superior GH ligament resist?
ER and inferior/anterior translation
taut in anatomical neutral
What does the middle GH ligament resist?
anterior translation
taut in 45-90 degrees abduction
What does the inferior GH ligament resist?
Anterior band (strongest):
- anterior translation
taut in 90 abd & ER
Posterior band:
taut in 90 degrees abd & IR
Axillary pouch:
- inferior translation
taut in 90 degrees abd
What does the coracohumeral ligament resist?
inferior translation & ER
taut in anatomical neutral
What are the static stabilizers of the GHJ?
Non-contractile
- capsular ligaments
- glenoid labrum
What are the dynamic stabilizers of the GHJ?
contractile tissue
- rotator cuff
- biceps LH
What is dynamic centralization?
- the contractile & passive tension keeping GHJ congruency
- infraspinatus limits capsular slack/stabilizes anterior slide of humeral head
- passive tension of subscapularis, middle GH ligament, and coracohumeral ligament balances posterior forces
What is the rotator cuff interval?
- anterior/superior part of the capsule that rotator cuff does not cover/blend
common site for anterior dislocations
Which muscles are responsible for flexion of the GHJ?
- anterior deltoid
- coracobrachialis
- biceps brachii
Which muscles are responsible for extension of the GHJ?
- posterior deltoid
- lats
- teres major
- triceps LH
- pec major (sternocostal head)
Which muscles are responsible for abduction of the GHJ?
- middle deltoid
- supraspinatus
- anterior deltoid
Which muscles are responsible for external rotation of the GHJ?
- infraspinatus
- teres minor
- posterior deltoid
Which muscles are responsible for internal rotation of the GHJ?
- subscapularis
- pec major
- lats
- teres major
- anterior deltoid
What are the consequences on the GHJ of a downwardly rotated scapular position?
- decreased compressive forces
- increased risk for subluxation/dislocation inferiorly
- plastic deformation of SCS
What are the consequences on the subacromial space of a downwardly rotated scapular position?
- increased compression of the subacromial space
- pain
- limited ROM
What structures live in the subacromial space?
- supraspinatus tendon
- subacromial bursa
- biceps LH tendon
- superior capsule
What effect will a tight posterior capsule of the GHJ have on the humeral head during elevation?
- can displace humeral head too far anteriorly
- leads to subacromial impingement syndrome
What are the 6 principles needed for proper arm abduction kinematics?
1) scapulohumeral rhythm
2) SC elevation & AC upward rotation
3) clavicle retracts at SCJ
4) scapula posteriorly tilts & ER’s
5) clavicle posteriorly rotates
6) GHJ ER’s
What is scapulohumeral rhythm?
- scapula and humerus move together in order to perform full ROM
- 2:1 ratio (2 degrees GHJ; 1 degree STJ)
AFTER 30 degrees abduction:
- every 3 degrees of movement comes from 2 degrees of GHJ and 1 degree of STJ
What compensation during shoulder abduction might you see if the rotator cuff is not working properly and the upper trap is overactive?
- shoulder shrugging
- upper trap stronger than rotator cuff
- trap-serratus imbalance
Explain the force couple for scapular upward rotation
- serratus anterior pulls inferior angle anterior
- upper trap elevates GHJ
- lower trap depresses medial boarder
Explain the force couple for glenohumeral abduction
- supraspinatus rolls humeral head
- deltoids translate
inferior slide from:
- subscapularis
- infraspinatus
- teres minor
- passive lats/teres major
Explain the consequences of a habitual rounded shoulders posture
- depressed, downwardly rotated, protracted, slight IR, anterior tilted scapula
- increased risk of subacromial impingement
- could lead to elevated clavicle @ SCJ & depressed ACJ
What is scapular dyskinesis?
- paralysis/weakness of trapezius & serratus anterior (& middle trap)
- no upward rotation w/ abduction
What are the effects on scapulothoracic and glenohumeral joint kinematics with scapular dyskinesis?
- scapula downwardly rotated w/ resisted elevation
- winging scapula due to ineffective serratus anterior (doesn’t maintain congruency w/ thoracic cage)
- snapping scapula
- abnormal position of scapula: reduced upward rotation, excessive downward rotation, IR, anterior tilt, or elevation
Explain scapular diakinesis’s effect on regions near the shoulder girdle
- pec minor will shorten overtime
- thoracic kyphosis
- subacromial impingement
Explain scapular dyskinesis’s effect on other structures that live in the shoulder girdle
- deltoid & supraspinatus shorten leading to ineffective length-tension relationship
- can reduce volume in subacromial space
- serratus anterior paralysis
- GHJ ligament & muscle abnormalities
- RTC degeneration
Why would once chose to strengthen the shoulder in the scapular plane rather than pure abduction?
- more natural compared to pure abduction
- more room to move w/o ER of shoulder
- greater tubercle under high point of acromion
- allows humeral head to be oriented more directly into glenoid fossa
What is subacromial impingement syndrome?
- reduced inferior slide leads to humerus jamming into subacromial structures in subacromial space
- reduced volume within subacromial space
What pathologies can arise from repetitive overhead throwing and why?
- subacromial impingement
- RTC syndrome
- Ball-throwers fracture (spiral fracture in distal 3rds of the humerus)
- little league shoulder (epiphysis becomes fractured or displaced)
- tears/degeneration w/ ER
What is shoulder instability?
- excessive laxity associated with pain, apprehension, or lack of function
- most common anterior and inferior
What are some causes of shoulder instability?
- Glenohumeral internal rotation deficit (GIRD)
- RTC syndrome
What is the difference between a slap tear and a bankart tear?
SLAP:
- superior labrum anterior to posterior
- biceps LH “peel-back” mechanism at end range of ER
- 90 degree abduction & endrange ER
Bankart tear:
- anterior-inferior rim of glenoid
- leads to instability
How would hypomobility at the GHJ affect the SCJ and ACJ?
- total humeral ROM reduced
- can combine w/ STJ to improve ROM
- lead to scapular substitution
How would hypomobility at the SCJ affect the GHJ and ACJ?
- decreased clavicular elevation, rotation, retraction, and scapular upward rotation
- increased scapular IR
- elevation dependent on GHJ
- limited ACJ upward rotation because decreased clavicular posterior rotation
How would hypomobility at the ACJ affect the SCJ and GHJ?
(usually HYPERmobility)
- scapular motion limited
- SCJ motion limited due to clavicular connection to ACJ
- Clavicular protraction brings scapula into thorax
What are the AAOS norms for shoulder flexion/extension?
Flexion:
- 180
Ext:
- 60
What are the AAOS norms for shoulder abduction/adduction?
Abduction:
- 180
Adduction:
- 0
What are the AAOS norms for shoulder IR/ER?
IR:
- 70
ER:
- 90
