Shoulder joint

Question 1

What is another term for the shoulder joint?

Answer 1

Glenohumeral

Question 2

What type of joint is it?

Answer 2

Ball and socket joint - sits between the humerus and scapula

Question 3

The shoulder joint is one of the most mobile joints at the expense of…

Answer 3

Stability

Question 4

The joint is formed by the articulation of the head of humerus with the…cavity

Answer 4

glenoid (fossa of the scapula)

Question 5

Is it a synovial joint?

Answer 5

Yes

Question 6

What cartilage covers the articulating surfaces?

Answer 6

Hyaline

Question 7

Why does the joint have inherent instability?

Answer 7

The head of the humerus is much larger than the glenoid fossa - to reduce the disproportionate surfaces the fossa is deepened by a fibrocartilage rim = glenoid labrum

Question 8

Describe the joint capsule

Answer 8

• Fibrous sheath that encloses the structures of the joint
• From anatomical neck of humerus to border of glenoid fossa
• capsule is lax to permit greater mobility
• synovial membrane lines inner surface of joint capsule

Question 9

What does the synovial membrane produce?

Answer 9

Synovial fluid

Question 10

What is the role of synovial bursae?

Answer 10

Reduce friction in joint

Question 11

What is a bursae?

Answer 11

Fluid filled sac - acts a cushion between structures

Question 12

What are the most clinically important bursae?

Answer 12

Subacromial

Subscapular

Question 13

What ligaments are there?

Answer 13

1) Glenohumeral - superior, middle, inferior
- connect humerus to glenoid fossa
- main source of shoulder stability, holding it in place and preventing anterior dislocation

2) Coracohumeral - base of coracoid process to greater tubercle of humerus
- supports superior part of joint capsule

3) Coraco-clavicular - maintain alignment of clavicle in relation to scapula
4) Coracoacromial - forms the coracoacromial arch which prevents superior displacement of humeral head
5) Transverse humeral - holds tendon of long head of biceps in the intertubercular groove

Question 14

What muscles are responsible for extension?

Answer 14

Posterior deltoid
Latissimus dorsi
Teres major

Question 15

What muscles are responsible for flexion?

Answer 15

Pectoralis major
Anterior deltoid
Coracobrachialis
Biceps brachii weakly assist

Question 16

What muscles are responsible for abduction?

Answer 16

First 15 degrees = supraspinatus
15-90 = middle fibres deltoid
past 90 = the scapula needs to be rotated - trapezius and serratus anterior

Question 17

What muscles are responsible for adduction?

Answer 17

Pectoralis major
Latissimus dorsi
Teres major

Question 18

What muscles are responsible for internal rotation?

Answer 18

Subscapularis 
Pectoralis major
Latissimus dorsi
Teres major
Anterior deltoid

Question 19

What muscles are responsible for external rotation?

Answer 19

Infraspinatus

Teres minor

Question 20

What factors contribute to joint mobility?

Answer 20

Ball and socket joint
Shallow glenoid cavity and large humeral head
Inherent laxity of joint capsule

Question 21

What factors contribute to stability?

Answer 21

Rotator cuff muscles
Glenoid labrum
Ligaments
Biceps tendon

Question 22

What are the rotator cuff muscles?

Answer 22

Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 23

What innervates teres minor?

Answer 23

Axillary nerve

Question 24

What innervates Supraspinatous and infraspinatous?

Answer 24

Suprascapular nerve

Question 25

What arteries supply the shoulder joint?

Answer 25

Anterior and posterior circumflex humeral arteries - branches of axillary artery
Branches of suprascapular artery (branch of thyrocervical trunk) also contribute