130 - Joints of Upper Limb 1 - Shoulder Complex Flashcards

1
Q
Components of synovial joints
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5
A

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

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2
Q

Consequence of having a lot of hyaline cartilage on a bone

A

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

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3
Q

Structure from which most pain comes in a broken bone

A

Periosteum

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4
Q

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

A

Synovial membranes

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5
Q
Examples of 'special' synovial joint structures
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A

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

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6
Q

Labrum

A

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)

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7
Q

Fat pad

A

Intra-articular, extra-synovial structures.

Fill out irregularly-shaped structures in joints

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8
Q

Ligaments

A

Thickenings of capsule (intrinsic) or extrinsic ligaments.

Stabilise joints

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9
Q

What can a ligamentous injury in children involve?

A

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

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10
Q

Discs and menisci

A

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

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11
Q

Bursae

A

Can communicate with joint cavity.

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

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12
Q

What does stability of mobile joints often depend on?

A

Short fixator or stabiliser muscles

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13
Q

Joints of the clavicle
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2

A

Sternoclavicular joint.

Acromioclavicular joint.

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14
Q

Feature on the posterior aspect of scapulae

A

Spinous process.

Divides into supraspinous fossa and infraspinous fossa

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15
Q

How do muscles attach to scapula?

A

With muscle attachment, not tendinous attachment.

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16
Q

Lateral fossa on scapulae

A

Glenoid fossa

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17
Q

Processes overhanging gelnoid fossa

A

Acromion process.

Coracoid process

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18
Q

Where does the acromion process come from?

A

Part of the spinous process of the scapula

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19
Q

Function of clavicles

A

Orientates the shoulder laterally for greater ROM.

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20
Q

Where does clavicle articulate with midline?

A

On bulbous part

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21
Q

Why is the clavicle curved?

A

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

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22
Q

Two ligamentous attachments to clavicle

A

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

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23
Q

How do the clavicles orientate the shoulders?

A

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

24
Q

Most common site of clavicular fracture

A

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

25
Q

Mechanics of clavicular fracture

A

Sternocleidomastoid pulls medial clavicle upwards.

26
Q

Key features of sternoclavicular joint
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2

A

1) Intra-articular disc & strong capsule

2) Very stable joint Costoclavicular (accessory) ligament – main limitation to movement

27
Q

Main limiter of sternoclavicular joint movement

A

Costoclavicular ligament

28
Q

Effect of a disc on a joint

A

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

29
Q

Movements of the sternoclavicular joint
1
2

A
  • Disc increases complexity of movement on each side of it

* Elevation/depression with rotation about longitudinal axis

30
Q

Costoclavicular ligament

A

Joins first rib and medial clavicle.

An accessory ligament that is the main limiter of movement in the costoclavicular joint

31
Q

How common is sternoclavicular subluxation?

A

Very rare.

Often associated with trauma

32
Q

Biggest danger with sternoclavicular subluxation

A

Subclavian artery and vein can be endangered

33
Q
Features of acromioclavicular joint 
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A

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

34
Q

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

A

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

35
Q
Concentric rings of structures in glenohumeral joint 
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A
  • 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)
36
Q

Fracture sites of humerus
1
2
3

A
  • Surgical neck (common in elderly) – endangers axillary nerve
  • Mid-shaft – endangers radial nerve
  • Supracondylar – endangers median nerve & brachial artery
37
Q

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

A

Radial nerve

38
Q

What does a supracondylar fracture of the humerus endanger?

A

Median nerve, brachial artery

39
Q

Traction epiphyses

A

Epiphyses to which a muscle attaches

40
Q

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

A

Axillary nerve

41
Q

What makes the glenohumeral joint unstable?

A

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

42
Q

When is the glenohumeral joint particularly unstable?

A

Abduction

43
Q

Where does the capsule of the glenohumeral joint travel?

A

Past the anatomical neck to the surgical neck.

Allows for greater ROM

44
Q

Attachment of biceps tendon

A

Superior attachment to glenoid labrum

45
Q

Shape of glenohumeral capsule

A

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)

46
Q

Glenohumeral capsule deficiencies

A

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

47
Q

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

A

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

48
Q

Bursa that goes through deficiency in glenohumeral capsule

A

Subscapularis bursa

49
Q

Location of rotator cuff muscles

A

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

50
Q
Muscles of the rotator cuff
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A

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

51
Q

Subscapularis

A

Internal rotation

52
Q

Supraspinatus

A

Attaches to superior part of capsule.

Passes under coracoacromial ligament

53
Q

Common rotator cuff pathology

A

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.

54
Q

Least significant stabiliser of glenohumeral joint

A

Coracoacromial ligament and bursa

55
Q

What is the coracoacromial bursa susceptible to?

A

Irritation during shoulder abduction.