Shoulder Joint

Question 1

What is the shoulder joint also known as?

Answer 1

The glenohumeral joint

Question 2

What kind of joint is the shoulder joint?

Answer 2

Ball and socket

Question 3

What is the shoulder joint between?

Answer 3

The scapula and the humerus

Question 4

What does the shoulder joint do?

Answer 4

It is the major joint connecting the upper limb to the trunk

Question 5

How does the mobility of the shoulder joint compare to the rest of the body?

Answer 5

It is one of the most mobile joints in the human body

Question 6

What is the compromise for the mobility of the shoulder joint?

Answer 6

Less stable

Question 7

What is the shoulder joint formed by?

Answer 7

The articulation of the head of the humerus with the glenoid cavity of the scapula

Question 8

What are the articulating surfaces of the shoulder joints covered with?

Answer 8

Hyaline cartilage

Question 9

What gives rise to the shoulder joints inherent instability?

Answer 9

The head of the humerus is much larger than the glenoid fossa

Question 10

How is the disproportion of the articulating surfaces of the shoulder joint reduced?

Answer 10

The glenoid fossa is deepened by a fibrocartilage rim, called the glenoid labrum

Question 11

What is the joint capsule of the shoulder joint?

Answer 11

A fibrous sheath which encloses the structures of the joint

Question 12

What does the joint capsule of the shoulder joint extend?

Answer 12

From the anatomical neck of the humerus to the border of the glenoid fossa

Question 13

What is the result of the joint capsule of the shoulder being lax?

Answer 13

It permits greater mobility, particularly abduction

Question 14

What does the synovial membrane of the shoulders joint capsule line?

Answer 14

The inner surface of the joint capsule

Question 15

What does the synovial membrane of the shoulders joint capsule produce?

Answer 15

Synovial fluid

Question 16

Why does the synovial membrane of the shoulders joint capsule produce synovial fluid?

Answer 16

To reduce friction between the articular surfaces

Question 17

How is friction in the shoulder joint reduced?

Answer 17

By the presence of several synovial bursae

Question 18

What is a bursa?

Answer 18

A synovial fluid filled sac

Question 19

What do bursa act as?

Answer 19

Cushions between tendons and other joint structures

Question 20

What are the clinically important bursa in the shoulder joint?

Answer 20

Subacromial

Subscapular

Question 21

Where is the subacromial bursa located?

Answer 21

Inferiorly to the deltoid and acromion

Superiorly to the supraspinatus tendon and the joint capsule

Question 22

What does the subacromial bursa do?

Answer 22

Supports the deltoid and supraspinatus muscles

Question 23

What can inflammation in the subacromial bursa lead to?

Answer 23

Several shoulder problems

Question 24

Where is the subscapular bursa located?

Answer 24

Between the subscapularis tendon and the scapula

Question 25

What is the function of the subscapular bursa?

Answer 25

Reduces wear and tear on the tendon during movement at the shoulder joint

Question 26

What is the purpose of the ligaments in the shoulder joint?

Answer 26

They play a key role in stabilising the bony structures

Question 27

What are the majority of the ligaments in the shoulder?

Answer 27

Thickenings of the joint capsule

Question 28

What are the ligaments of the shoulder joint?

Answer 28

Glenohumeral ligaments (superior, middle and inferior)  Coroacohumeral ligament  Transverse humeral ligament Coracoacromial ligament

Question 29

What does the glenohumeral ligament consist of?

Answer 29

Three bands

Question 30

Where do the glenohumeral ligaments run?

Answer 30

With the joint capsule, from the glenoid fossa to the anatomical neck of the humerus

Question 31

What do the glenohumeral ligaments act to do?

Answer 31

Stabilise the anterior aspect of the joint

Question 32

What does the coracohumeral ligament attach?

Answer 32

The base of the coracoid process to the greater tubercle of the humerus

Question 33

What does the coroacohumeral ligament act to do?

Answer 33

Support the superior part of the joint capsule

Question 34

Where is the transverse humeral ligament?

Answer 34

It spans the distance between the two tubercles of the humerus

Question 35

What does the transverse humeral ligament act to do?

Answer 35

Hold the tendon of the long head of the biceps in the intertubecular groove

Question 36

How is the coracoacromial ligament unlike the other ligaments of the shoulder joint?

Answer 36

It is not a thickening of the joint capsule

Question 37

Where does the coracoacromial ligament run?

Answer 37

Between the acromion and coracoid process of the scapula

Question 38

What does the coracoacromial ligament form?

Answer 38

The coraco-acromial arch

Question 39

What does the coraco-acromial arch overlie?

Answer 39

The shoulder joint

Question 40

What is the purpose of the coraco-acromial arch?

Answer 40

It prevents superior displacement of the humeral head

Question 41

What is the arterial supply to the shoulder joint via?

Answer 41

The anterior and posterior circumflex humeral arteries, and the suprascapular artery.  Branches from these arteries form an anastomotic network around the joint

Question 42

How is the shoulder joint innervated?

Answer 42

By the axillary, suprascapular and lateral pectoral nerves

Question 43

What are the nerves that supply the shoulder joint derived from?

Answer 43

Roots C5 and C6 of the brachial plexus

Question 44

What is the result of the innervation of the shoulder joint being from the brachial plexus?

Answer 44

A upper brachial plexus injury will affect shoulder joint function

Question 45

What is an upper brachial plexus injury called?

Answer 45

Erb’s palsy

Question 46

What is the result of the shoulder being a ball-and-socket type joint?

Answer 46

A wide range of movement is permitted

Question 47

What movements does the shoulder joint permit?

Answer 47

Extension (upper limb backward in sagittal plane) Flexion (upper limb forwards in sagittal plane) Abduction (upper limb away from midline in coronal plane) Adduction (upper limb towards the midline in coronal plane) Medial rotation (rotation towards the midline, so the thumb is pointing medially) Lateral rotation (rotation away from the midline, so the thumb is pointing laterally)

Question 48

What is extension at the shoulder joint produced by?

Answer 48

The posterior deltoid, latissimus dorsi and teres major

Question 49

What is flexion at the shoulder joint produced by?

Answer 49

The biceps brachii (both heads), pectoralis major, anterior deltoid and coracobrachialis

Question 50

How is abduction at the shoulder joint produced?

Answer 50

The first 0-15 degrees of abduction is produced by the supraspinatus  The middle fibres of the deltoid are responsible for the next 15-90 degrees  Past 90 degrees, the scapula needs to be rotated to achieve abduction, which is carried out by the trapezius and serratus anterior

Question 51

What produces adduction at the shoulder joint?

Answer 51

Contraction of the pectoralis major, lattissimus dorsi and teres major

Question 52

How is adduction at the shoulder joint produced?

Answer 52

By contraction of the pectoralis major, latissimus dorsi and teres major

Question 53

How is medial rotation of the shoulder joint produced?

Answer 53

By contraction of the subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid

Question 54

How is lateral rotation of the shoulder joint produced?

Answer 54

Contraction of the infraspinatus and teres minor

Question 55

What factors contribute to the mobility of the shoulder joint?

Answer 55

Type of joint- ball and socket  Bony surfaces Laxity of joint capsule

Question 56

What bony surfaces contribute to the mobility of the shoulder joint?

Answer 56

Shallow glenoid cavity and large humeral head- there is a 1:4 disproportion in surfaces

Question 57

What factors contribute to the stability of the shoulder joint?

Answer 57

Rotator cuff muscles  Glenoid labrum  Ligaments

Question 58

What do the rotator cuff muscles do?

Answer 58

Surround the shoulder joint, attaching to the tubercles of the humerus, whilst also fusing with the joint capsule

Question 59

How do the rotator cuff muscles act to stabilise the shoulder joint?

Answer 59

The resting tone of the muscles act to ‘pull’ the humeral head into the glenoid cavity

Question 60

What is the glenoid labrum?

Answer 60

A fibrocartilaginous ridge surrounding the glenoid cavity

Question 61

What does the glenoid labrum do?

Answer 61

Deepens the cavity, reducing the dislocation

Question 62

What do the ligaments of the shoulder act to do?

Answer 62

Reinforce the joint capsule | Form the coraco-acromial arch

Question 63

Clinically, what are dislocations at the shoulder described by?

Answer 63

Where the humeral head lies in relation to the infraglenoid tubercle

Question 64

What are the most prevalent shoulder dislocations?

Answer 64

Anterior dislocations, although posterior dislocations can sometimes occur

Question 65

What prevents superior movement of the humeral head?

Answer 65

The coraco-acromial arch

Question 66

What is an anterior shoulder dislocation usually caused by?

Answer 66

Excessive extension and lateral rotation of the humerus

Question 67

What happens when there is excessive extension and lateral rotation of the humerus?

Answer 67

The humeral head is forced anteriorly and inferiorly, into the weakest part of the joint capsule.

Question 68

What is tearing of the joint capsule associated with?

Answer 68

An increased risk of future dislocations

Question 69

What runs in close proximity to the shoulder joint?

Answer 69

The axillary nerve

Question 70

What is the result of the axillary nerve running in close proximity to the shoulder joint?

Answer 70

It can be damaged in dislocation

Question 71

What does injury to the axillary nerve cause?

Answer 71

Paralysis to the deltoid, and loss of sensation over the regimental badge area

Question 72

Why can a dislocation stretch the radial nerve?

Answer 72

As it is tightly bound in the radial groove

Question 73

What is the important role of the rotator cuff muscles?

Answer 73

Stabilising the glenohumeral joint

Question 74

How common is injuries of the rotator cuff muscles?

Answer 74

Relatively common

Question 75

Why is injury of the rotator cuff muscles relatively common?

Answer 75

Because they are often under heavy strain

Question 76

What does tendonitis refer to?

Answer 76

Inflammation of the muscle tendons

Question 77

What is tendonitis usually due to?

Answer 77

Overuse

Question 78

What does rotator cuff tendonitis cause over time?

Answer 78

Degenerative changes in the subacromial bursa, and the supraspinatus tendon

Question 79

What do the changes found in rotator cuff tendonitis lead to?

Answer 79

Increased fiction between the structures of the joint

Question 80

What is the characteristic sign of rotator cuff tendonitis?

Answer 80

The ‘painful arc’

Question 81

What is the painful arc?

Answer 81

Pain in the middle of abduction

Question 82

What causes the painful arc?

Answer 82

When the affected area comes into contact with the acromion