Clinical - Frozen Shoulder Flashcards
What is the most common cause of shoulder pain, especially as you get older?
Rotator cuff disease
What are the 4 joints of the shoulder?
- Glenohumeral 2. Acromioclavicular 3. Sternoclavicular 4. Scapulothoracic
What is the glenohumeral joint?
Arguably the true shoulder joint - between the glenoid fossa of the scapula and the head of the humerus
What is the acromioclavicular (AC) joint?
Joint between the acromion of the scapula and the clavicle
What is the sternoclavicular joint?
Joins shoulder to axial skeleton - joint between sternum and clavicle
What is the scapulothoracic joint?
Arguably not a true joint but acts like one - gathers the sternoclavicular and AC joints at the junction between the anterior surface of the scapula and the thoracic cage. Where anterior surface of scapula comes into communication with posterior part of chest wall.
Diagram of head of humerus and tuberosities
What runs in the bicipital groove?
Bicep tendon
Diagram of glenoid fossa
What is the glenoid labrum? What is its function?
Fibrocartilage rim attached around the margin of the glenoid cavity - function is to deepen the shallow gleniod fossa, but depsite this it is still not a true ball and socket joint
What is the glenoid fossa deepend by?
Glenoid labrum
What encloses the strucutres of the glenohumeral joint?
The joint capsule - a fibrous sheath that extends from the anatomical neck of the humerus to the border or ‘rim’ of the glenoid fossa.
What lines the inner surface of the joint capsule of the glenohumeral joint?
Synovial membrane
What does the synovial membrane produce? What is purpose of this?
Synovial fluid - reduces friction between the articular surfaces.
What type of joint is the glenohumeral joint?
Synovial joint
What is a synovial joint?
Joins bones or cartilage with a fibrous joint capsule
Why is the glenohumeral joint so unstable?
Due to large head of humerus and small glenoid fossa –> poor fit for ball and socket joint
The capsule of the glenohumeral joint is lax. What does this allow?
Relaxed - allows rotation and elevation (greater mobility)
What is highlighted in blue?
Joint capsule
The joint capsule of the glenohumeral is thicker anteriorly. Why is this?
Risk of anterior dislocation - main source of stability for the shoulder, holding it in place and preventing it from dislocating anteriorly.
What are the ligaments of the shoulder?
- Glenohumeral
- Coracohumeral
- Transverse humeral
- Coracoacromial ligament
- Acromioclavicular ligament
- Coraco–clavicular ligament
What are the glenohumeral ligaments?
Superior, middle and inferior
Function of glenohumeral ligaments?
They are the main source of stability for the shoulder, holding it in place and preventing it from dislocating anteriorly. They act to stabilise the anterior aspect of the joint.
What do the 3 glenohumeral ligaments form?
Joint capsule - ligaments connect the humerus to the glenoid fossa
Where does the coraco-acromial ligament run? What is its function?
Running between the acromion and coracoid process of the scapula, it forms the coraco-acromial arch
What ligaments support the AC joint?
- Acromioclavicular ligament
- Coracoclavicular ligament
Where does the acromioclavicular ligament run? What is its function?
Runs horizontally from the acromion to the lateral clavicle. It covers the joint capsule, reinforcing its superior aspect.
Reinforce the joint capsule and serves as the primary restraint to posterior translation and posterior axial rotation at the AC joint
Where does the coraco–clavicular ligament run? What is it composed of?
- Composed of the trapezoid and conoid ligaments
- Runs from the clavicle to the coracoid process of the scapula
What is function of coracoclavicular ligament?
Work alongside the acromioclavicular ligament to maintain the alignment of the clavicle in relation to the scapula.
They have significant strength but large forces can rupture these ligaments as part of an acromio-clavicular joint (ACJ) injury.
Does the AC joint have much movement?
Little movement; full abduction, adduction + flex
What structure has to slide underneath coracoacromial ligament? What problem can this cause?
Part of rotator cuff - supraspinatus
Can cause impingement
How is the sternoclavicular able to move? How does this help with movement?
Rotates with elevation 30-40 degrees
Allows wider range of movement of humerus
What muscles does scapula serve as origin for?
Rotator cuff muscles, deltoid and trapezius
What are the 4 rotator cuff muscles?
- Supraspinatus
- Infraspinatus
- Subscapularis
- Teres minor
Which rotator cuff is found anteriorly? What is its function?
Subscapularis - originates from the subscapular fossa and attaches to the lesser tubercle of the humerus.
Medially rotates arm.
Which rotator cuff muscles are found posteriorly?
Supraspinatus, infraspinatus, teres minor
What are attachments of supraspinatus?
Originates from the supraspinous fossa of the scapula (above spine of scapula), attaches to the greater tubercle of the humerus.
Actions of supraspinatus?
Abducts the arm 0-15 degrees, and assists deltoid for 15-90
Attachments of infraspinatus?
Originates from the infraspinous fossa of the scapula (below spine of scapula), attaches to the greater tubercle of the humerus.
Actions of infraspinatus?
Laterally rotates arm
Attachments of the teres minor?
Originates from the posterior surface of the scapula, adjacent to its lateral border. It attaches to the greater tubercle of the humerus.
Actions of the teres minor?
Laterally rotates the arm.
What is the collective function of the rotator cuff muscles?
Originate from the scapula and attach to the humeral head.
Collectively, the resting tone of these muscles acts to ‘pull’ the humeral head into the glenoid fossa. This gives the glenohumeral joint a lot of additional stability.
What are the extrinsic muscles of the shoulder?
Trapezius, Latissimus Dorsi, Levator Scapulae, Rhomboid Major and Rhomboid Minor