Shoulder
Swelling of the shoulder joint may be visible due to a joint effusion, or synovial thickening. Deformity of the joint and fractures and dislocations are usually obvious (figure 37a,b). Table 4 provides details of the muscles of the shoulder and figure 38a–d illustrations of the anterior and posterior bones and muscles of the upper limb.
Table 4 Muscles of the shoulder joint and upper arm
Shoulder
- Sternal and clavicular heads of sternomastoid
- Clavicular and acromial attachments of trapezius
- Sternal and clavicular heads of pectoralis major, and laterally to outer lip of bicipital groove.
- Clavicular and acromial attachments of deltoid: distally to midshaft humerus.
- Pectoralis minor
- Coracobrachialis: distally to medial humeral midshaft
- Short head of biceps
- Supraspinatus
- Subscapularis
- Long head of triceps
- Latissimus dorsi: rotates around teres major to floor of bicipital groove
- Teres major
- Brachioradialis
- Brachialis
- Extensor carpi radialis longus
- Common extensor origin
- Pronator teres: distally to lateral radial midshaft
- Common flexor origin
- Flexor digitorum superficialis: distal split onto middle phalanx
- Supinator: from lateral ulna around posterior aspect of upper radius
- Ulnar head of pronator teres
- Radial attachment of biceps
- Flexor digitorum profundus: to distal phalanx
- Flexor pollicis longus: to base of distal phalanx
- Pronator quadratus: between adjacent radius and ulna
- Flexor carpi ulnaris
- Abductor pollicis longus
- Tendons of extensor carpi radialis longus and brevis
- Extensor pollicis brevis
- Extensor pollicis longus
- Sternal and clavicular heads of sternomastoid
- Trapezius
- Brachial plexus
- Subclavian artery
- Sternal and clavicular heads of pectoralis major
- Deltoid
- Axillary artery
- Biceps, short head
- Biceps, long head
- Serratus anterior
- Median nerve
- Radial nerve
- Brachial artery
- Common flexor origin
- Brachioradialis
- Pronator teres
- Biceps tendon and aponeurosis
- Flexor carpi ulnaris
- Flexor carpi radialis
- Ulnar artery
- Radial artery
- Palmaris longus, overlying median nerve at wrist
- Ulnar nerve
- Thenar muscles
- Hypothenar muscles
- Levator scapulae
- Coracoid process
- Trapezius
- Supraspinatus
- Deltoid: spine and acromion, to
- Infraspinatus
- Rhomboideus minor and major
- Teres minor
- Infraspinatus
- Long head of triceps
- Teres minor
- Rhomboideus minor and major
- Lateral heads of triceps
- Deltoid tuberosity of humerus
- Teres major
- Latissimus dorsi
- Medial heads of triceps
- Anconeus
- Anconeus
- Supinator
- Linear attachment on subcutaneous border of ulna of extensor carpi ulnaris, flexor carpi ulnaris and flexor digitorum profundus
- Abductor pollicis longus
- Extensor pollicis longus
- Extensor pollicis brevis
- Extensor indicis
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor carpi ulnaris (through pisometacarpal ligament)
- Extensor pollicis longus
- Extensor digitorum longus
Figure 38d Upper limb anatomy: posterior muscles
- Trapezius
- Acromion
- Spine of scapula
- Deltoid
- Infraspinatus
- Axillary nerve: impalpable but important relation to surgical neck of humerus
- Teres minor
- Teres major
- Long head of triceps
- Radial nerve: palpable through the fibres of triceps
- Latissimus dorsi
- Tendon to upper border of olecranon
- Lateral epicondyle
- Ulnar nerve: lying on back of medial epicondyle
- Olecranon process
- Anconeus
- Brachioradialis and common extensor muscles
- Common flexor muscles
- Extensor digitorum longus
- Extensor carpi ulnaris
- Abductor pollicis longus
- Extensor pollicis brevis
- Tendons of extensor carpi radialis longus and brevis
- Extensor pollicis longus
- Dorsal digital expansion over metacarpophalangeal joints
The shoulder joint allows flexion, extension, abduction, adduction, external and internal rotation and circumduction. Flexion (figure 39a,b) is possible to 180 degrees when the arm is swung forward as in marching. This involves some scapular movement, the glenohumeral joint contributing about 90 degrees. Extension (figure 39c,d) of the shoulder is possible to 65 degrees, when the arm is swung backwards.
Arm abduction takes place at both the glenohumeral joint and through scapular rotation. On its own, assessed by fixing the scapular, the former is to 90 degrees (figure 40a,b).
When the movement of the scapular is included 180 degrees are possible, however, there is also external rotation of the shoulder joint for the greater tuberosity to clear the acromion. The scapular movement in abduction can be observed from behind, noting the position of the inferior angle, at rest, at 90 degrees and 180 degrees abduction (figure 41a–c).
The pectoralis major and lattissimus dorsi muscles are powerful adductors from the abducted position, as in raising the body from an overhead bar, pulling objects towards you and in the follow through of a tennis serve. They can be tested and palpated by asking the subject to press their hands together (figure 42) or downwards on their hips
Adduction (figure 43a,b) is possible to 50 degrees in a normal joint, when the elbow is carried forward across the front of the chest.
External rotation (figure 44a–c) is to 60 degrees. This is assessed with a flexed elbow, placing the hand behind the head. The movement, however, combines abduction with external rotation.
Internal rotation of the shoulder joint is stopped when the flexed forearm meets the trunk. However, resisted movement can be tested in this position (figure 45a,b); ask the subject to scratch the middle of their back, with the thumb as high as possible, to check the full rotation of 90 degrees (figure 45c).
