Week 1 - Shoulder joint and girdle

Question 1

Describe the acromioclavicular joint

Answer 1

Synovial and small

Limited movement as there are no specific muscles for movement at this joint

Question 2

What is the main joint of the shoulder girdle?

Answer 2

Sternoclavicular joint

Question 3

Describe the sternoclavicular joint

Answer 3

Mismatched surfaces: broad clavicular surface, narrow sternal surface
Has an intra-articular disc
Strong ligaments associated with it - costoclavicular

Question 4

Describe the glenohumeral (scapulohumeral) joint

Answer 4

Synovial ball and socket joint
Multi-axial
High mobility, compromises stability
Subject to intense wear and tear

Question 5

What rims the glenoidal labrum?

Answer 5

White fibrocartilage, thinner than normal articular cartilage

Question 6

Describe the glenohumeral joint capsule when the arm is in a resting position

Answer 6

Inferior and anterior portions are lax, superior portion is taut
Inferior is loose because the capsular attachment of the joint is far away from the articular margin of the humerus, but is close to the glenoid

Question 7

What reinforces the anterior portion of the glenohumeral joint capsule?

Answer 7

The superior, middle and inferior glenohumeral ligaments, which form a Z-shaped pattern on the capsule
These are intracapsular ligaments

Question 8

Which muscles support the GH joint capsule?

Answer 8

The rotator cuff muscles, supporting it superiorly, posteriorly and anteriorly

Question 9

Where are the attachments of the GH joint capsule?

Answer 9

Glenoid - just outside the labrum

Humerus - superiorly is close to articular margin, interiorly is 1cm below margin

Question 10

On which side is the GH joint vulnerable?

Answer 10

The inferior side

Question 11

What four things supply stability to the GH joint?

Answer 11

Coracoacromial arch
Rotator cuff (dynamic stability)
Coraco-clavicular ligament
Tendon of biceps

Question 12

What makes up the coracoacromial arch?

Answer 12

Acromion + coraco-acromial ligament + coracoid process

Question 13

What four muscles make up the rotator cuff?

Answer 13

Subscapulaaris, infraspinatus, supraspinatus and Teres minor

Question 14

How does the subscapularis move the humerus?

Answer 14

Rotates inwards

Question 15

How do the infraspinatus and teres minor move the humerus?

Answer 15

Rotate it outwards

Question 16

How do the rotator cuff muscles provide dynamic stability to the GH joint?

Answer 16

The joint capsule has sensory nerves, which are linked directly to the RC muscles via A-alpha nerve fibres. These carry any stretch from the capsule of ligament almost instantaneously, providing dynamic stability without compromising movement

Question 17

What connects the coracoid process to the clavicle? Why is this important?

Answer 17

Two very strong ligaments called the coraco-clavicular ligaments. These are very thick
Important because acromioclavicular joint isn’t very strong - these ligaments transfer weight from the humerus to the clavicle

Question 18

What are two important bursae in the GH joint?

Answer 18

Subacromial-subdeltoid bursa, the biggest one which is commonly inflamed
Subscapula bursae, found between the muscle/tendon and the scapula. Commonly communicates with joint synovial cavity through a hole in the cavity. This also increases chance of infection

Question 19

Describe flexion and extension of the arm

Answer 19

In a sagittal plane, the arm moves forwards in flexion, and backwards in extension

Question 20

Which large muscle is able to abduct the GH joint? Why?

Answer 20

The deltoid

It’s the only large muscle lateral to the joint. The others are medial and so adduct it

Question 21

How can the Pec major move the GH joint?

Answer 21

Adduct, flex and rotate the joint

Question 22

What are the four main flexors of the shoulder?

Answer 22

Pec major
Anterior deltoid
Subscapularis
Bicep brachii

–> any flexor anterior to the joint

Question 23

How would you test whether Pec major is working?

Answer 23

Examine adduction

Question 24

What is the most powerful extensor of the shoulder? What are some other extensors?

Answer 24

The Latissimus dorsi

Teres major, posterior deltoid, infraspinatus and teres minor are extensors as they are posterior to the joint

Question 25

How do the lats move the shoulder joint?

Answer 25

Extensorly, nad adduct it, as they come from the medial side, attaching to the front of the humerus, like the pec major

Question 26

Which part of the deltoid is an abductor of the shoulder joint?

Answer 26

The part on the acromion - middle region, lateral to the joint, which is also the thickest part
This abduction is also limited by bony factors

Question 27

Which muscle initiates abduction of the shoulder?

Answer 27

The supraspinatus - only once humerus is at a certain angle does the deltoid take over

Question 28

How would you test paralysis of the supraspinatus?

Answer 28

Whether the patient can abduct the shoulder while standing upright. If paralysed they’ll need to lean to the side to create the appropriate angle for the deltoid to start abduction

Question 29

Which parts of the shoulder are involved in abduction?

Answer 29

Glenohumeral
Humerus
Pectoral girdle
Scapula and clavicle also rotate once glenohumeral joint has reached limit of movement (at the top)

Question 30

What are the two major muscles involved in glenohumeral adduction?

Answer 30

Pec major and Lat

Anterior and posterior deltoid also plays a role

Question 31

How do you tell if a muscle is a medial rotator?

Answer 31

If it’s in front of the joint i.e. pec major, Lat, subscapuaris anterior deltoid and T major

Question 32

What are some lateral rotators of the shoulder?

Answer 32

Infraspinatus, teres minor

Infra is the major one

Question 33

How do the trap muscles move the scapula?

Answer 33

Pull it in (retraction) and up (elevation)

Levator scapulae helps with elevation

Question 34

What does girdle-glenohumeral harmony refer to?

Answer 34

Glenohumeral abduction is limited to 90 degrees, further abduction is accompanied by girdle movement, largely at the SC joint, though there’s some at the AC joint