Shoulder Flashcards
What joints are part of the shoulder complex?
- Glenohumeral joint
- Acromioclavicular joint (synovial plane = gliding)
- Sternoclavicular joint (synovial plane = gliding) – closed pack position: maximum shoulder elevation
- Scapulothoracic joint (not a true joint but works with AC & SC joints)
What are key anatomical features of the shoulder?
- Glenoid covers 25-30% of the humeral head, making it an unstable joint
- Limited subacromial space
- Glenoid faces anterolaterally and moves in the scapular plane
- Contains the subacromial bursa and rotator cuff tendons
What are the main ligaments of the glenohumeral joint?
- Coracohumeral ligament
- Superior, middle, and posterior glenohumeral ligaments
What are the ligaments of the acromioclavicular joint?
- Coracoclavicular ligament
- Acromioclavicular ligament
- Coracohumeral ligament
What are the ligaments of the sternoclavicular joint?
- Interclavicular ligament
- Anterior/posterior sternoclavicular ligaments
- Costoclavicular ligament
What is the shoulder joint capsule?
- Attached to the labrum and glenoid rim, extending to the humerus
- Inferiorly, extends 1-2 cm onto the humeral neck
- Reinforced by the rotator cuff and the long head of the biceps
What is the function of the subacromial bursa?
- Largest bursa in the body
- Lies between the deltoid and coracoacromial arch (superior) and the rotator cuff (inferior)
- Well vascularized and highly innervated
- Contains inflammatory cells in patients with impingement/tendinopathy
What is the role of the rotator cuff?
- The rotator cuff (RC) tendons are interconnected and attach to the humerus
- They integrate with:
- The glenohumeral joint (GHJ) capsule
- The coracohumeral ligament
- The RC tendons do not function independently – stress on one part affects the whole structure
How does the scapula move during arm elevation?
- Movement is controlled by a force couple of the trapezius and serratus anterior:
- Upper trapezius: Upward rotation, retraction, and elevation
- Lower trapezius: Upward rotation, retraction, and depression
- Serratus anterior: Upward rotation and protraction
What muscles are involved in arm elevation?
- Deltoid: Prime mover at the GHJ
- Rotator cuff (RC): Works with the deltoid to stabilize the humeral head
- Infraspinatus/teres minor + subscapularis: Counteract the deltoid’s upward pull
- Long head of biceps: Exerts a downward force, keeping the humeral head centered
What is the relationship between impingement and instability?
- Impingement and instability are interconnected – one can lead to the other
- If instability occurs first, the RC compensates, leading to inflammation and impingement
- If impingement occurs first, RC weakness leads to laxity and eventual instability
What happens in a slumped posture?
- Arms move into internal rotation
- Humeral head shifts anteriorly and superiorly
- Tight posterior capsule limits internal rotation
- Sitting slumped with hands interlocked encourages these changes
How do you palpate the sternoclavicular joint?
- Located at the medial end of the clavicle
How do you find the clavicle?
- Palpate laterally along its shaft:
- Medial 2/3 is convex anteriorly
- Lateral 1/3 is concave
Where is the coracoid process?
- An anterior projection below the lateral part of the clavicle
Where is the acromion?
- The expanded lateral end of the scapular spine, found by tracing the spine to its lateral point (acromial angle)
How do you find the acromioclavicular joint?
- Apply downward pressure on the lateral end of the clavicle
How do you palpate the greater and lesser tuberosities of the humerus?
- Greater tuberosity: Most lateral bony point at the shoulder
- Lesser tuberosity: Just lateral to the coracoid; disappears with internal rotation
Where is the intertubercular sulcus (bicipital groove)?
- Mnemonic: “2 majors watching Little Miss Dorsi in a ditch”
- Lateral: Pectoralis major
- Medial: Teres major
- Bicipital Groove: Latissimus dorsi
How do you palpate the long head of the biceps?
- Found between the greater and lesser tuberosities in the bicipital groove
What is the normal range of motion for the shoulder?
- Flexion: 180°
- Extension: 50°
- Abduction: 180°
- Adduction: 50°
- Internal & External Rotation: 90°
