Shoulder girdle

Published on 11/03/2015 by admin

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Last modified 22/04/2025

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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.

image

Fig. 5.1 Right clavicle (superior aspect).

A–Shaft

B–Posterior border

C–Acromial end

D–Anterior border

E–Sternal end.

image

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)

image

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.

image

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.

image

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.

image

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

Scapular notch –

lateral end of the superior border.

Coracoid process –

expanded portion, lateral to the scapular notch; provides attachment for the coracoclavicular ligament, short head of biceps and the coracobrachialis muscles.

Ossification

Primary centre

For the body appears near the glenoid cavity – 8th week intrauterine life.

Secondary centres

7 centres:

coracoid process appears age 1, fuses with body age 15;

acromion process, 2 centres appear at puberty;

subarachnoid region appears at puberty;

lower part of glenoid cavity appears age 14–17;

medial border appears at puberty;

inferior angle appears at puberty.

Fuse with body age 20.

Radiographic appearances of the scapula (Figs 5.7 and 5.8)

image

Fig. 5.7 Left shoulder joint and scapula: anteroposterior projection.

A–Glenoid cavity

B–Medial border

C–Inferior angle

D–Chest wall

E–Lateral border

F–Shaft of humerus

G–Intertubercular sulcus (Bicipital groove)

H–Lesser tuberosity

I–Greater tuberosity

J–Head of humerus

K–Acromion

L–Acromioclavicular joint

M–Coracoid process

N–Clavicle

O–Spine of scapula

P–Superior angle.

(From Bryan 1996.)

image

Fig. 5.8 Left scapula: lateral projection.

1 – Clavicle

2 – Acromion process

3 – Spine of scapula

4 – Head of humerus

5 – Shaft of humerus

6 – Inferior angle

7 – Body of scapula

8 – Ribs

9 – Coracoid process.

(From Bryan 1996.)

Fractures

Body, neck, acromion and coracoid process

Cause –

direct blow.

Example of treatment –

sling, for comfort.

Shoulder joint (Figs 5.9 and 5.10)

Type

Synovial ball and socket joint.

image

Fig. 5.9 Right shoulder joint (coronal section).

A–Fibrous capsule

B–Synovial membrane

C–Synovial membrane

D–Tendon of long head of biceps

E–Head of humerus

F–Fibrous capsule

G–Synovial membrane

H–Glenoid labrum

I–Glenoid cavity of scapula

J–Articular hyaline cartilage

K–Synovial fluid

L–Glenoid labrum.

image

Fig. 5.10 Right shoulder joint (anterior aspect).

1 – Coracoacromial ligament

2 – Coracohumeral ligament

3 – Transverse humeral ligament

4 – Tendon of long head of biceps

5 – Fibrous capsule

6 – Inferior glenohumeral ligament

7 – Middle glenohumeral ligament

8 – Superior glenohumeral ligament.

Bony articular surfaces

Head of the humerus with the glenoid cavity of the scapula. The articular surfaces are covered with articular hyaline cartilage.

Fibrous capsule

Forms a cylindrical sleeve which is attached medially to the rim of the glenoid cavity and laterally to the anatomical neck of the humerus. The capsule is loose inferiorly to allow movement.

Synovial membrane

Lines the fibrous capsule, encloses the tendon of the long head of biceps and medially is reflected over the glenoid labrum. The membrane secretes synovial fluid, which lubricates the joint.

Subscapular bursa –

lies between the joint and the subscapularis muscle.

Subacromial bursa –

lies between the shoulder joint and the acromion process.

Strengthening ligaments

Glenohumeral ligaments (superior, middle and inferior) –

from the glenoid cavity of the scapula to the lesser tuberosity and the anatomical neck of the humerus.

Coracohumeral ligament –

from the coracoid process of the scapula to the greater tuberosity of the humerus.

Transverse humeral ligament –

lies between the lesser and greater tuberosities of the humerus and maintains the tendon of the long head of biceps in the intertubercular sulcus (bicipital groove).

Tendons

These reinforce the fibrous capsule, forming the ‘rotator cuff’:

Supraspinatus tendon attached to the superior aspect of the greater tuberosity of the humerus.

Infraspinatus tendon attached to the middle of the greater tuberosity of the humerus.

Teres minor attached to the lower, posterior aspect of the greater tuberosity of the humerus.

Subscapularis tendon attached to the anterior aspect of the lesser tuberosity of the humerus.

Intracapsular structures

Glenoid labrum –

fibrocartilaginous rim round the glenoid cavity to deepen the socket.

Tendon of biceps, long head

Movements

Flexion by the pectoralis major and the anterior fibres of the deltoid.

Extension by the posterior fibres of the deltoid and teres major, assisted by the latissimus dorsi.

Abduction by the deltoid.

Adduction by the pectoralis major and latissimus dorsi, assisted by the teres major.

Medial rotation by the pectoralis major, anterior fibres of the deltoid, teres major and subscapularis.

Lateral rotation by the posterior fibres of the deltoid, infraspinatus and teres minor.

Circumduction – a combination of the above movements.

Blood supply

Branches of the axillary and subclavian arteries.

Nerve supply

Suprascapular, axillary and lateral pectoral nerves.

Radiographic appearances of the shoulder joint (Figs 5.11 to 5.15)

image

Fig. 5.11 Left shoulder: anteroposterior projection.

A–Clavicle

B–Coracoid process

C–Shaft of humerus

D–Lateral border of scapula

E–Glenoid cavity

F–Head of humerus

G–Acromion process.

image

Fig. 5.12 Left shoulder joint: lateral projection.

1 – Coracoid process

2 – Glenoid cavity

3 – Head of humerus

4 – Shaft of humerus

5 – Clavicle.

(From Bryan 1996.)

image

Fig. 5.13 Shoulder: double contrast CT arthrogram.

A–Head of humerus

B–Air

C–Shoulder joint

D–Contrast medium

E–Scapula

F–Lung

G–Rib.

(From Bryan 1996.)

image

Fig. 5.14 Shoulder, rotator cuff tear (arrowed). MR scan.

(From Resnick Kransdorf, 2005.)

image

Fig. 5.15 Shoulder, abnormal glenoid labrum (arrowed). CT arthrotomogram.

(From Resnick Kransdorf, 2005.)

Trauma

Anterior dislocation

Cause –

fall on the outstretched hand

Example of treatment –

reduction under anaesthetic. Sling for support.

Posterior dislocation (Fig. 5.16)

Cause –

direct below on the anterior aspect of the shoulder.

image

Fig. 5.16 Shoulder joint, posterior dislocation. CT scan.

(From Resnick Kransdorf, 2005.)

Example of treatment –

as for anterior dislocation.

Recurrent dislocation

Cause –

due to detachment of the glenoid labrum.

Example of treatment –

surgery.

Pathology

Calcification of tendons

Most commonly affects the supraspinatus.

Causes –

acute tendinitis, insignificant trauma and chronic tendinitis; degeneration of the tendon near its insertion following injury. May affect the ‘rotator cuff’ muscles.

Acromioclavicular joint (Fig. 5.17)

Type

Synovial plane joint.

image

Fig. 5.17 Right acromioclavicular joint (coronal section).

A–Fibrous capsule

B–Articular disc

C–Fibrocartilage

D–Acromion process of scapula

E–Synovial fluid

F–Synovial membrane

G–Fibrous capsule

H–Fibrocartilage

I–Acromial end of clavicle.

Bony articular surfaces

The acromial end of the clavicle with the medial aspect of the acromion process of the scapula. The articular surfaces are covered with fibrocartilage.

Fibrous capsule

Attached to the lateral end of the clavicle and the medial aspect of the acromion process of the scapula.

Synovial membrane

Lines the fibrous capsule and is reflected over the lateral aspect of the articular disc. The membrane secretes synovial fluid, which lubricates the joint.

Supporting ligaments

Acromioclavicular ligament –

from the superior aspect of the acromion process to the superior aspect of the clavicle.

Coracoclavicular ligament –

from the coracoid process of the scapula to the conoid tubercle and the trapezoid line of the clavicle.

Intracapsular structure

Articular disc –

in the upper aspect of the joint, wider superiorly, sometimes absent.

Movements

Gliding.

Blood supply

Suprascapular artery –

branch of the subclavian artery.

Thoraco-acromial artery –

branch of the axillary artery.

Nerve supply

Suprascapular and lateral pectoral nerves.

Radiographic appearances of the acromioclavicular joint (Fig. 5.18)

image

Fig. 5.18 Right acromioclavicular joint: anteroposterior projection.

A–Acromioclavicular joint

B–Acromion process

C–Head of humerus

D–Clavicle.

(From Bryan 1996.)

Trauma

Subluxation (partial dislocation)

Cause –

fall on the shoulder.

Example of treatment –

sling worn for support.

Coracoclavicular ligament torn.

Dislocation

Cause –

fall on the shoulder.

Example of treatment –

internal fixation of the acromion and clavicle with a steel pin, removed after the ligament has healed.

Sternoclavicular joint (Fig. 5.19)

Type

Synovial saddle joint.

image

Fig. 5.19 Right sternoclavicular joint (coronal section).

A–Sternal end of clavicle

B–Fibrocartilage

C–Synovial fluid

D–Articular disc

E–Fibrous capsule

F–Synovial fluid

G–Fibrocartilage

H–Clavicular notch of manubrium sterni

I–Synovial membrane

J–Fibrous capsule.

Bony articular surfaces

The sternal end of clavicle with the clavicular notch of the manubrium sterni and 1st costal cartilage. The articular surfaces are covered with fibrocartilage.

Fibrous capsule

Attached to the sternal end of the clavicle and the lateral aspect of the manubrium sterni. The capsule thins superiorly and inferiorly.

Synovial membrane

Lines the fibrous capsule and is reflected over the articular disc. The membrane secretes synovial fluid, which lubricates the joint.

Strengthening ligaments

Anterior and posterior sternoclavicular ligaments

Interclavicular ligament

– unites the sternal ends of the clavicles.

Costoclavicular ligament

Intracapsular structure

Articular disc –

divides the joint into 2 distinct parts.

Movements

Elevation.

Depression.

Anterior movement in a horizontal direction.

Posterior movement in a horizontal direction.

Circumduction.

Blood supply

Internal mammary arteries and suprascapular arteries, which are branches of the subclavian artery.

Nerve supply

Anterior supraclavicular nerve.

Radiographic appearances of the sternoclavicular joint (Fig. 5.20)

image

Fig 5.20 Sternoclavicular joint: anterior oblique projection.

A–Left clavicle

B–Thoracic vertebra

C–Manubrium sterni

D–Left sternoclavicular joint

E–Right clavicle

F–1st rib.

(From Bryan 1996.)

Trauma

Dislocation (Fig. 5.21)

Rare.

image

Fig. 5.21 Right sternoclavicular joint, posterior dislocation. CT scan.

(From Resnick Kransdorf, 2005.)

Cause –

fall on the shoulder, forcing the inner end of the clavicle forwards and upwards.

Example of treatment –

reduction under anaesthetic; sling.

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