Shoulder Flashcards
What are the shoulder movements?
Extension, flexion, abduction, adduction, medial rotation, lateral rotation, circumduction
What is the characteristic of the acromion variation according to Bigliani?
Acromion has a hook shape
How does the glenoid fossa affect mobility and instability?
It is highly unstable which creates high mobility
What role does the labrum play in the glenoid fossa?
Increases stability
What are the characteristics of the plane of the scapula?
Superior aspect is 30-45° anterior to frontal plane, slight anterior inclination, upward rotation in frontal plane
Is arm elevation easier when the scapula is in its plane or out of plane?
Easier when scapula is in its plane
Under which type of shoulder rotation is arm elevation easier?
Under external shoulder rotation
Why is elevation easier with external shoulder rotation?
The greater tubercle can clear the acromion process and acromioclavicular ligaments
What are the joints of the shoulder?
- Acromioclavicular joint
- Glenohumeral joint
- Scapulothoracic joint
- Sternoclavicular joint
What are the characteristics of the acromioclavicular joint?
3 rotatory motions and 3 translatory motions
What are the ligaments of the acromioclavicular joint?
- Coracoclavicular (trapezoid and conoid)
- Acromioclavicular
What does the trapezoid ligament do?
Prevents medial movement of acromion process relative to clavicle
What does the conoid ligament do?
Restricts upward rotation of scapula and pulls clavicle in upward rotation
What are the grades of acromioclavicular joint injuries?
- Grade I: AC ligament stretched partially torn
- Grade II: AC ligament completely torn
- Grade III: AC joint separation
What are the rotary motions of the sternoclavicular joint?
- Elevation/depression
- Protraction/retraction
- Upward/downward rotation
What are the ligaments of the sternoclavicular joint?
- Anterior/posterior sternoclavicular
- Interclavicular
- Costoclavicular
- Intraarticular disc
What is the scapulothoracic joint?
Not a real joint with no true articulations
What are the functions of the scapulothoracic joint?
- Increase ROM of shoulder
- Enhance reach
- Maintain favourable length-tension relationship for deltoid
- Maintain G-H stability
- Shock absorption
- Permits elevation of body
What is the glenohumeral joint type?
Ball and socket
What is the scapulohumeral rhythm?
2:1 GH:ST; for every 2° of GH movement there is 1° of ST movement
What are the contributions of shoulder joints to 180° of arm elevation?
- GH = 120° abduction
- ST = 60° upward rotation
- SC = 30° elevation and posterior rotation
- AC = 30° upward rotation
What elements are responsible for static glenohumeral stability?
- Coracohumeral ligament
- Glenohumeral ligament
- Labrum
- Capsule
- Joint contact
- Scapular inclination
- Intraarticular pressure
What elements are responsible for dynamic glenohumeral stability?
- Rotator cuff muscles
- Biceps
- Deltoid
How is shoulder instability classified?
- Etiology: traumatic vs atraumatic
- Degree of instability: subluxation vs dislocation
- Unidirectional vs multidirectional
- Generalized ligamentous laxity
What are the characteristics of the coracoacromial arch?
- Coracoacromial ligament
- Sub-acromial space
- Roof of glenohumeral joint
What is impingement in the shoulder?
Irritation of structures in subacromial space leading to narrowing of subacromial space
What are intrinsic and extrinsic mechanisms of impingement?
- Intrinsic: factors within tendon
- Extrinsic: glenohumeral kinematics, anatomical factors
What are the impingement tests?
- Neer’s test
- Hawkin’s test
How is glenohumeral instability compensated?
Scapulothoracic joint use
What muscles stabilize the glenohumeral joint?
- Supraspinatus
- Infraspinatus
- Subscapularis
- Teres minor
- Biceps
- Deltoid
What effect does the deltoid have on the humerus?
Translates humeral head superiorly
What does the supraspinatus do on the humerus?
Abduction of the humerus and compression of humeral head
What do the infraspinatus, subscapularis, and teres minor do on the humerus?
Pull humeral head downwards and externally rotate humerus
What happens if there is no rotator cuff function?
Excessive superior glide of humeral head
What muscles stabilize the scapula?
- Serratus anterior
- Trapezius
- Rhomboids
- Pectoralis minor
- Levator scapulae
What muscles perform upward scapular rotation?
- Upper trapezius
- Lower trapezius
- Serratus anterior
What causes medial winging of the scapula?
Serratus anterior weakness, long thoracic nerve damage
What causes lateral winging of the scapula?
Trapezial weakness, spinal accessory nerve damage
What muscles perform downward scapular rotation?
- Pectoralis minor
- Levator scapulae
- Rhomboids
What are the large muscle movers of the shoulder?
- Latissimus dorsi
- Teres major
- Pectoralis major
- Coracobrachialis
What muscles are involved in shoulder depression/weight bearing?
- Latissimus dorsi
- Pectoralis major
When is the moment arm of the upper extremity weight the highest?
When the shoulder is abducted at 90°
When is the joint reaction force highest in shoulder abduction?
At 90° of abduction
What does apprehension of the shoulder mean?
Anterior instability
What does the sulcus sign indicate?
Inferior instability
What does the load and shift test assess?
Anterior-posterior instability
