5 Shoulder girdle

Chapter contents

Clavicle

Fractures

Scapula

Fractures

Shoulder joint

Trauma

Pathology

Acromioclavicular joint

Trauma

Sternoclavicular joint

Trauma

Clavicle (Figs 5.1 and 5.2)

Type

Long bone, but it has no medullary cavity and is ossified from a membrane.

Fig. 5.1 Right clavicle (superior aspect).

A–Shaft

B–Posterior border

C–Acromial end

D–Anterior border

E–Sternal end.

Fig. 5.2 Right clavicle (inferior aspect).

1 – Facet for the acromion

2 – Trapezoid line

3 – Conoid tubercle

4 – Posterior border

5 – Facet for the sternum

6 – Facet for the 1st costal cartilage

7 – Anterior border.

Position

Runs horizontally from the base of the neck to the shoulder and is subcutaneous throughout.

Articulations

The sternal end of the clavicle with the clavicular notch of the manubrium sterni to form the sternoclavicular joint.

The acromial end of the clavicle with the acromion process of the scapula to form the acromioclavicular joint.

Main parts

Shaft –

‘S’ shaped.

Sternal end –

slightly expanded, quadrangular, medial aspect.

Acromial end –

slightly expanded, flattened, lateral aspect.

Facet for the 1st costal cartilage –

on the inferior aspect of the sternal end.

Conoid tubercle –

on the postero-inferior aspect of the acromial end, coracoclavicular ligament attached.

Trapezoid line –

ridge extending laterally from the conoid tubercle, coracoclavicular ligament attached.

Ossification

Primary centres

2 centres in the shaft –

5th week intrauterine life.

Then fuse to form 1 centre at age 45 days.

Secondary centres

1 centre:

Sternal end appears age 18–20.

Sternal end fuses with the shaft age 18–25.

N.B. The clavicle is the first bone to ossify.

Radiographic appearances of the clavicle (Figs 5.3 and 5.4)

Fig. 5.3 Left clavicle: anteroposterior projection.

A–Conoid tubercle

B–Suprascapular notch

C–Coracoid process

D–Acromion

E–Acromioclavicular joint

F–Lateral one-third

G–Medial two-thirds.

Fig. 5.4 Left clavicle: posteroanterior projection.

1 – Acromion

2 – Coracoid process

3 – 1st rib

4 – Conoid tubercle

5 – Acromioclavicular joint.

(From Bryan 1996.)

Fractures

Junction of the middle and outer third

Cause –

fall on the outstretched hand.

Example of treatment –

reduced by holding the shoulder back by a figure-of-eight bandage.

Scapula (Figs 5.5 and 5.6)

Type

Flat, triangular-shaped bone.

Fig. 5.5 Left scapula (costal aspect).

A–Scapular notch

B–Superior angle

C–Subscapular fossa

D–Medial border

E–Inferior angle

F–Lateral border

G–Neck

H–Glenoid cavity

I–Coracoid process

J–Acromion process.

Fig. 5.6 Left scapula (dorsal aspect).

1 – Acromion process

2 – Spine

3 – Lateral border

4 – Inferior angle

5 – Medial border

6 – Infraspinous fossa

7 – Supraspinous fossa

8 – Superior angle

9 – Coracoid process.

Position

Posterior bone of the shoulder girdle, lying on the postero-lateral aspect of the bony thorax extending from the 2nd–7th ribs.

Articulations

Acromion process of the scapula with the acromial end of the clavicle to form the acromioclavicular joint.

Glenoid cavity of the scapula with the head of the humerus to form the shoulder joint.

Main parts

Posterior aspect

Body –

triangular in shape.

Spine –

narrow ridge dividing the upper third from the lower two-thirds; forms attachment for the trapezius and deltoid muscles.

Supraspinous fossa –

depression above the spine for the supraspinatus muscle.

Infraspinous fossa –

depression below the spine for the infraspinatus muscle.

Acromion process –

broadened, lateral aspect of the spine; on the medial border there is an articular facet for the clavicle.

Superior angle –

at the junction between the superior and medial borders.

Inferior angle –

at the junction between the medial and lateral borders.

Medial (vertebral) border –

palpable for most of its length.

Lateral (axillary) border –

teres minor is attached below the infraglenoid tubercle.

Spinoglenoid notch –

at the junction of the spine and the neck.

Acromial angle –

junction of the acromion and spine, posteriorly.

Lateral aspect

Head of scapula –

at the lateral angle, formed at the junction of the superior and lateral borders.

Glenoid cavity –

‘pear shaped’ depression for the head of the humerus on the lateral aspect of the head of the scapula.

Supraglenoid tubercle –

superior aspect of the glenoid cavity, tendon of long head of biceps attached.

Infraglenoid tubercle –

inferior aspect of the glenoid cavity; provides attachment for the tendon of long head of triceps muscle.

Anterior aspect

Subscapular fossa –

large depression for the subscapularis muscle.

Superior border

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