130 - Joints of Upper Limb 1 - Shoulder Complex

Question 1

Components of synovial joints
1
2
3
4
5

Answer 1

1) Articular cartilage – avascular & aneural
2) Fibrous capsule – may be reinforced by stabilizer muscles
3) Capsule strengthened by intrinsic ligaments
4) Extrinsic (accessory ligaments) may be primarystabilisers
5) Synovial membrane - linesall non-articular surfaces

Question 2

Consequence of having a lot of hyaline cartilage on a bone

Answer 2

Only will have a narrow area where blood vessels can enter (hyaline cartilage is avascular).
Therefore bone is vulnerable to necrosis

Question 3

Structure from which most pain comes in a broken bone

Answer 3

Periosteum

Question 4

What lines all non-articular surfaces in a synovial joint?

Answer 4

Synovial membranes

Question 5

Examples of 'special' synovial joint structures
1
2
3
4
5
6

Answer 5

1) Labrum
2) Fat pad
3) Intra-casular tendon
4) Discs, menisci
5) Bursae
6) Ligaments

Question 6

Labrum

Answer 6

A fibro-cartilagenous rim that deepens the socket in ball-and-socket joints.
Increases congruence of a joint quite markedly (EG: by 1/3 in shoulder joint)

Question 7

Fat pad

Answer 7

Intra-articular, extra-synovial structures.

Fill out irregularly-shaped structures in joints

Question 8

Ligaments

Answer 8

Thickenings of capsule (intrinsic) or extrinsic ligaments.

Stabilise joints

Question 9

What can a ligamentous injury in children involve?

Answer 9

An avulsion injury (because ligament is stronger than growing bone)

Question 10

Discs and menisci

Answer 10

Shock absorb.
Might bear weight.
Have blood and nerve supply to outer third.
EG: In knee

Question 11

Bursae

Answer 11

Can communicate with joint cavity.

If it can communicate, can have flow of synovial fluid into communicating bursa, EG: In the case of infection.

Question 12

What does stability of mobile joints often depend on?

Answer 12

Short fixator or stabiliser muscles

Question 13

Joints of the clavicle
1
2

Answer 13

Sternoclavicular joint.

Acromioclavicular joint.

Question 14

Feature on the posterior aspect of scapulae

Answer 14

Spinous process.

Divides into supraspinous fossa and infraspinous fossa

Question 15

How do muscles attach to scapula?

Answer 15

With muscle attachment, not tendinous attachment.

Question 16

Lateral fossa on scapulae

Answer 16

Glenoid fossa

Question 17

Processes overhanging gelnoid fossa

Answer 17

Acromion process.

Coracoid process

Question 18

Where does the acromion process come from?

Answer 18

Part of the spinous process of the scapula

Question 19

Function of clavicles

Answer 19

Orientates the shoulder laterally for greater ROM.

Question 20

Where does clavicle articulate with midline?

Answer 20

On bulbous part

Question 21

Why is the clavicle curved?

Answer 21

So that it doesn’t impinge on structures (EG: blood vessels, nerves) that travel under the clavicles

Question 22

Two ligamentous attachments to clavicle

Answer 22

Both on underside of clavicle.
Costoclavicular ligament
Coraco-clavicular ligament

Question 23

How do the clavicles orientate the shoulders?

Answer 23

Gleno-humeral rhythm.
Clavicles change orientation with shoulder movement to orientate glenohumeral joint.
About 2:1 ratio of movement for shoulder joint to clavicle.

Question 24

Most common site of clavicular fracture

Answer 24

Between lateral 1/3 and medial 2/3 (where there is the greatest change in curvature).

Question 25

Mechanics of clavicular fracture

Answer 25

Sternocleidomastoid pulls medial clavicle upwards.

Question 26

Key features of sternoclavicular joint 1 2

Answer 26

1) Intra-articular disc & strong capsule | 2) Very stable joint Costoclavicular (accessory) ligament – main limitation to movement

Question 27

Main limiter of sternoclavicular joint movement

Answer 27

Costoclavicular ligament

Question 28

Effect of a disc on a joint

Answer 28

Increases the complexity of movement, one of which is rotation.

Question 29

Movements of the sternoclavicular joint 1 2

Answer 29

* Disc increases complexity of movement on each side of it | * Elevation/depression with rotation about longitudinal axis

Question 30

Costoclavicular ligament

Answer 30

Joins first rib and medial clavicle. | An accessory ligament that is the main limiter of movement in the costoclavicular joint

Question 31

How common is sternoclavicular subluxation?

Answer 31

Very rare. | Often associated with trauma

Question 32

Biggest danger with sternoclavicular subluxation

Answer 32

Subclavian artery and vein can be endangered

Question 33

``` Features of acromioclavicular joint 1 2 3 4 ```

Answer 33

1) Plane synovial joint – articular surfaces in sagittal plane 2) Weak capsule 3) Main stabiliser coracoclavicular ligament - 2 parts separated by bursa 4) Both parts prevent upward rotation of clavicle at AC joint

Question 34

Arrangement of articular surfaces that makes acromioclavicular joint liable to be injured

Answer 34

Articulate in sagittal plane, so face in direction most likely to encounter force

Question 35

``` Concentric rings of structures in glenohumeral joint 1 2 3 4 5 ```

Answer 35

* Layer 1 - bones (most interior layer) * Layer 2 - labrum – deepens socket * Layer 3 - capsule –reinforced by intrinsic ligaments * Layer 4 - tendons –“rotator cuff” * Layer 5 – coraco-acromial (accessory) ligament/arch & sub-acromial bursa)

Question 36

Fracture sites of humerus 1 2 3

Answer 36

- Surgical neck (common in elderly) – endangers axillary nerve - Mid-shaft – endangers radial nerve - Supracondylar – endangers median nerve & brachial artery

Question 37

What does a mid-shaft fracture of the humerus endanger?

Answer 37

Radial nerve

Question 38

What does a supracondylar fracture of the humerus endanger?

Answer 38

Median nerve, brachial artery

Question 39

Traction epiphyses

Answer 39

Epiphyses to which a muscle attaches

Question 40

What does a fracture of the humerus at the surgical neck endanger?

Answer 40

Axillary nerve

Question 41

What makes the glenohumeral joint unstable?

Answer 41

Disproportionately large head of the humerus to the shallow glenoid fossa. Poor congruence.

Question 42

When is the glenohumeral joint particularly unstable?

Answer 42

Abduction

Question 43

Where does the capsule of the glenohumeral joint travel?

Answer 43

Past the anatomical neck to the surgical neck. | Allows for greater ROM

Question 44

Attachment of biceps tendon

Answer 44

Superior attachment to glenoid labrum

Question 45

Shape of glenohumeral capsule

Answer 45

Loose (folded inferiorly) to allow ROM in 3 planes - attaches to anatomical neck above; surgical neck below ‘Deficiencies’ anteriorly for: - long head of biceps - bursa (subscapular)

Question 46

Glenohumeral capsule deficiencies

Answer 46

‘Deficiencies’ anteriorly for: - long head of biceps - bursa (subscapular)

Question 47

What can happen if there is too little movement of the shoulder?

Answer 47

GLenohumeral capsule can constrict, leading to a decrease in ROM. 'Frozen shoulder'

Question 48

Bursa that goes through deficiency in glenohumeral capsule

Answer 48

Subscapularis bursa

Question 49

Location of rotator cuff muscles

Answer 49

‘Rotator cuff’ muscles located deep to deltoid – originate from scapula and insert into capsule – although have prime mover actions primary role as stabilizers

Question 50

``` Muscles of the rotator cuff 1 2 3 4 ```

Answer 50

1) Supraspinatus 2) Infraspinatus 3) Subscapularis 4) Teres minor

Question 51

Subscapularis

Answer 51

Internal rotation

Question 52

Supraspinatus

Answer 52

Attaches to superior part of capsule. | Passes under coracoacromial ligament

Question 53

Common rotator cuff pathology

Answer 53

If rotator cuff weak, humerus susceptible to slide upwards with pull of deltoid – may lead to entrapment (‘impingement’) especially of supraspinatus. This is because supraspinatus runs under coracoacromial ligament.

Question 54

Least significant stabiliser of glenohumeral joint

Answer 54

Coracoacromial ligament and bursa

Question 55

What is the coracoacromial bursa susceptible to?

Answer 55

Irritation during shoulder abduction.