Sternoclavicular Joint

Question 1

What kind of joint is the sternoclavicular joint?

Answer 1

Saddle-type synovial joint

Question 2

Where is the sternoclavicular joint?

Answer 2

Between the clavicle and manubrium of the sternum

Question 3

How is the sternoclavicular joint unique?

Answer 3

It is the only attachment of the upper limb to the axial skeleton

Question 4

Is the sternoclavicular joint a mobile joint?

Answer 4

Yes, very

Question 5

How can the sternoclavicular joint function?

Answer 5

Like a ball-and-socket type joint

Question 6

What does the sternoclavicular joint consist of?

Answer 6

The sternal end of the clavicle, the manubrium of the sternum, and part of the 1st costal cartilage

Question 7

What are the articular surfaces of the SC joint covered with?

Answer 7

Fibrocartilage (as opposed to hyaline cartilage, present in the majority of synovial joints)

Question 8

What is the SC joint separated into?

Answer 8

Two compartments

Question 9

How is the SC joint separated into two compartments?

Answer 9

By a fibrocartilaginous articular disc

Question 10

What does the joint capsule consist of?

Answer 10

A fibrous outer layer and an inner synovial membrane

Question 11

Where does the fibrous layer of the joint capsule extend?

Answer 11

From the epiphysis of the sternal end of the clavicle, to the borders of the articular surfaces and the articular disc

Question 12

What lines the inner surface of the joint capsule of the SC joint?

Answer 12

A synovial membrane

Question 13

What does the synovial membrane of the joint capsule of the SC joint do?

Answer 13

Produces synovial fluid

Question 14

What is the purpose of the synovial fluid in the joint capsule of the SC joint?

Answer 14

Reduces friction between articulating surfaces

Question 15

What do the ligaments of the sternoclavicular joint provide?

Answer 15

Much of its stability

Question 16

Where are the major ligaments of the sternoclavicular joint?

Answer 16

Sternoclavicular ligaments (anterior and posterior)
Interclavicular ligament
Costoclavicular ligament

Question 17

What do the sternoclavicular ligaments do?

Answer 17

Strengthen the joint capsule anteriorly and posteriorly

Question 18

What does the interclavicular ligament do?

Answer 18

Spans the gap between the sternal ends of each clavicle, and reinforces the joint capsule superiorly

Question 19

What often separates the two parts of the costoclavicular ligament?

Answer 19

A bursa

Question 20

Where do the two parts of the costoclavicular ligament bind?

Answer 20

At the 1st rib and cartilage inferiorly, and to the anterior and posterior borders of the clavicle superiorly

Question 21

What does the costoclavicular ligament do?

Answer 21

Very strong ligament, main stabilising force for the joint, resting elevation of the pectoral girdle

Question 22

What can the sternoclavicular and interclavicular ligaments be considered to be?

Answer 22

Thickenings of the joint capsule

Question 23

What is the arterial supply to the SC joint from?

Answer 23

The internal thoracic artery and suprascapular artery

Question 24

What is the SC joint supplied by?

Answer 24

The medial supraclavicular nerve (C3 and C4) and the nerve to the subclavius

Question 25

What movements require SC joint involvement?

Answer 25

Elevation of shoulders- shrugging shoulders of abducting the arm over 90º Depression of shoulders- dropping shoulders or extending the arm at the shoulder behind the boy Protraction of the shoulders- Moving the shoulder girdle anteriorly  Retraction of the shoulders- Moving the shoulder girdle posteriorly  Rotation- when the arm is raised over the head by flexion, the clavicle rotates passively as the scapula rotates

Question 26

How is the rotation of the scapula transmitted to the clavicle?

Answer 26

By the coracoclavicular ligaments

Question 27

What do the costoclavicular ligaments act as?

Answer 27

A pivot for the movements of the clavicle

Question 28

What is the sternoclavicular joint require for?

Answer 28

To accommodate the movements of the upper limb

Question 29

What is the result of the SC joint being required to accommodate the movements of the upper limb?

Answer 29

It has a high degree of mobility

Question 30

What does the SC joint require?

Answer 30

Much stability

Question 31

Why does the SC joint require much stability?

Answer 31

Because it’s the only connection between the upper limb and the axial skeleton

Question 32

What contributes to the SC joints mobility?

Answer 32

The type of joint  | The articular disc

Question 33

How does the type of joint contribute to the SC joints mobility?

Answer 33

Being a saddle joint, it can move in two axis

Question 34

What does the articular disc of the SC joint allow?

Answer 34

The clavicle and the manubrium to slide over each other more freely, allowing for the rotation and movement in a third axis

Question 35

What contributes to the stability of the SC joint?

Answer 35

Strong joint capsule  | Strong ligament

Question 36

Which ligament in particular contributes to the strength of the SC joint?

Answer 36

The costoclavicular ligament

Question 37

How does the costoclavicular ligament contribute to the strength of the SC joint?

Answer 37

It transfers stress from the clavicle to the manubrium (via the costal cartilage)

Question 38

How common is a dislocation of the sternoclavicular joint?

Answer 38

Quite rare

Question 39

What does a dislocation of the SC joint require?

Answer 39

Considerable force

Question 40

Why is a dislocation of the SC joint rare?

Answer 40

Because the costoclavicular ligament and the articular disc are highly effective at absorbing and transmitting forces away from the joint into the sternum

Question 41

What are the major types of sternoclavicular joint dislocation?

Answer 41

Anterior dislocations  | Posterior dislocations

Question 42

Which is the more common type of sternoclavicular joint dislocation?

Answer 42

Anterior

Question 43

How do anterior sternoclavicular joint dislocations occur?

Answer 43

Following a blow to the anterior shoulder which rotates the shoulder backwards

Question 44

How do posterior dislocations of the SC joint occur?

Answer 44

Normally result from a force driving the shoulder forwards, of from direct impact to the joint

Question 45

What is a sternoclavicular joint accompanied with in younger people?

Answer 45

A fracture through the epiphysial plate

Question 46

Why is a SC joint dislocation accompanied with a epiphyseal plate fracture in younger people?

Answer 46

Because the epiphyseal growth plate of the sternal end of the clavicle has not fully closed