Joints
Shoulder joint (glenohumeral joint)
A large humeral head in a small, shallow glenoid cavity: the most mobile joint in the body and therefore the least stable. The labrum deepens the socket by about half; the rotator cuff provides the active stability.
- Joint type
- Ball and socket joint (art. spheroidea), three degrees of freedom
- Body region
- Shoulder
- Latin name
- Articulatio humeri
Movements, axes and normal values
| Movement | Plane | Axis | Normal range | End feel |
|---|---|---|---|---|
| Forward flexion | sagittal | transverse (mediolateral) | 0-180 degrees, of which about 120 glenohumeral | elastic |
| Extension | sagittal | transverse (mediolateral) | 0-60 degrees | elastic |
| Abduction | frontal | sagittal (anteroposterior) | 0-180 degrees, of which about 120 glenohumeral | elastic |
| Adduction | frontal | sagittal (anteroposterior) | 0-45 degrees across the body | soft |
| External rotation | transverse | longitudinal (humeral shaft) | 0-90 degrees | elastic |
| Internal rotation | transverse | longitudinal (humeral shaft) | 0-70 degrees | elastic |
- Close-packed position
- 90 degrees of abduction with maximal external rotation
- Resting (loose-packed) position
- 55 degrees of abduction, 30 degrees of horizontal adduction
- Capsular pattern
- External rotation most limited, then abduction, then internal rotation
- Arthrokinematics
- A convex humeral head on a concave glenoid cavity: roll and glide run in opposite directions. During abduction the head rolls cranially and glides caudally. Without that caudal glide the greater tubercle jams against the acromion and impingement follows.
- Stability
- Passive: labrum, capsule and the three glenohumeral ligaments (the inferior one matters most in abduction and external rotation). Active: the rotator cuff, which centres the head in the socket.
- Scapulohumeral rhythm
- Almost all of the first 30 degrees of abduction comes from the glenohumeral joint (the setting phase); after that glenohumeral and scapulothoracic contribute in a ratio of about 2 to 1. At 180 degrees of arm elevation some 60 degrees of scapular rotation has therefore taken part.
- Palpation
- Coracoid process (2 cm caudal and medial to the lateral end of the clavicle), acromion, greater tubercle laterally under the acromion, intertubercular groove at 10 degrees of internal rotation.
- Clinical
- Subacromial pain syndrome with a painful arc between 60 and 120 degrees; frozen shoulder (adhesive capsulitis), recognisable by the capsular pattern; anterior instability and Bankart lesion after dislocation; rotator cuff tear.
- Source
- Kapandji, Physiologie articulaire deel 1; Neumann, Kinesiology of the Musculoskeletal System; Magee, Orthopedic Physical Assessment
Clinical tests
- Neer impingement test
- Hawkins-Kennedy test
- Empty can test
- Lift-off test
- Shoulder apprehension test
- Bear hug test
- Drop sign
- External rotation lag sign
- Full can test
- Hyperabduction test