MSK S3 Shoulder Joint

Question 1

What type of joint is the shoulder joint

Answer 1

Synovial, ball and socket joint

Question 2

Which two bones form the shoulder joint? Why is it said to be unstable?

Answer 2

Humerus and the glenoid fossa.

Said to be unstable because there is a 4:1 disproportion in area of surfaces.

Question 3

What is put in pace to try to reduce the disproportion of the area of the surfaces?

Answer 3

Glenoid labrum. A fibrocartilage rim.

Question 4

What other reasons cause the shoulder joint to be considered unstable?

Answer 4

The glenoid cavity/fossa is shallow
It allows multiplanar movements
The capsule is lax.

Question 5

What is a joint capsule?

Answer 5

It is a fibrous sheath which encloses the structures of a joint.

Question 6

How is stability of the shoulder joint achieved? What is most important?

Answer 6

Muscles of the rotator cuff (most important)
Glenoid labrum
Other muscles (deltoid, long head of biceps, triceps)
Ligaments
Capsule

Question 7

What are the 3 intra-capsule ligaments of the shoulder otherwise known?

Answer 7

Gleno-humeral ligaments

Superior, Middle and inferior

Question 8

What is the role of intracapsular ligaments of the shoulder joint?

Answer 8

They help to reinforce the joint anteriorly

Question 9

What are the 3 extra-capsular ligaments of the shoulder joint?

Answer 9

Coracoacromial ligament
Coracohumeral ligament
Transverse humeral ligament

Question 10

Where is the coracoacromial ligament found? What is it’s job?

Answer 10

It runs between the corocoid process of the scapula and the acromion of the scapula.

It prevents superior displacement of the humeral head. VERY STRONG

Question 11

Where is the Coracohumeral ligament? what is it’s job?

Answer 11

Runs from the base of the coracoid process (on the scapula) to the anterior part of the greater tubercle on the humerus. It supports the superior part of the joint capsule.

Question 12

Where is the transverse humeral ligament found? What is it’s job?

Answer 12

It spans the distance between the two tubercles of the humerus.
It holds to he tendon of the long head of biceps in place during shoulder movement.

Question 13

What makes up the coracoacromial arch? What is the role of it? When is it clinically important?

Answer 13

Acromion
Coracoid process
Coracoacromial ligament
Prevents up displacement of the humerus.
Clinically important in the painful arc syndrome.

Question 14

What gives the ‘cuff’ name to the rotator cuff muscles?

Answer 14

Their tendons blend in with each other to form a cuff, which fuses with the capsule and strengthens it.

Question 15

What does the subacromial bursa separate?

Answer 15

The supraspinatus tendon from the coracoacromial ligament

Question 16

What is the role of the synovial membrane in the shoulder joint?

Answer 16

It lines the capsule and the bone up to the edge of articulating surfaces

Question 17

What are the 2 main bursa found in the shoulder joint?

Answer 17

The subscapular and subacromial

Question 18

What is the role of the subacromial bursa?

Answer 18

It facilitates the movement of the supraspinatus tendin under the CAA snd the deltoid muscles over the SJ capsule and greater tubercle of the humerus.

Question 19

When (at what degrees) does painful arc syndrome occur? AB or ADduction?

Answer 19

50-130 degrees

Question 20

Name two causes of painful arc syndrome

Answer 20

Rotator cuff tendonitis (inflammation of the rotator cuff muscle tendons) or inflammation of the subacromial bursa.

Question 21

Where is the subscapular bursa found? What is it’s role?

Answer 21

Located between the subscapularis tendon and the scapula. It facilitates, specifically, movement of the subscapularis muscle over the scapula.

Question 22

What are the main blood supply to the shoulder joint?

Answer 22

Anterior and posterior circumflex arteries

Subscapular artery

Question 23

What is a bursa?

Answer 23

A synovial fluid filled sac

Question 24

What is the nerve supply to the shoulder joint?

Answer 24

Suprascapular nerve
Axillary nerve
Lateral pectoral nerves

Question 25

Clinically how are dislocations of the shoulder joint described?

Answer 25

By where the humeral head lies in relation to the Infraglenoid tubercle.

Question 26

What is an anterior dislocation usually caused by?

Answer 26

Excessive extension and lateral rotation of the humerus.

Question 27

What nerve(s) are most likely to be damaged during anterior dislocation of the shoulder joint?

Answer 27

Axillary -can lead to paralysis of the deltoid muscles and loss of sensation over regimental badge area.
Radial nerve - bound in radial groove