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MSK > 21 - Shoulder and Elbow Joint > Flashcards

21 - Shoulder and Elbow Joint Flashcards

1
Q

What is the bloody supply to triceps?

A

Profunda Brachii

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2
Q

What is in the cubital fossa?

A
  • brachial artery, median nerve medially, tendon of biceps laterally
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3
Q

What do I need to know?

A
  1. Bones that make up the shoulder joint and how it permits a wide range of movement
  2. know the ligaments and thicker regions of the capsule and how these support the shoulder
  3. Identify the bursa
  4. List and describe the actions of the actions of muscles
  5. Features of the long bones that make up the elbow joint (3 joints in 1)
  6. Arrangement of muscles, ligaments, bursa
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4
Q

The glenohumeral joint is the …. this means …

A

most mobile joint in the body. This means it requires a lot of control and is prone to injury

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5
Q

The glenohumeral joint is a … joint

A

Ball in socket, multiaxial joint synovial joint formed by the articulation of the head of the humerus and glenoid fossa of the scapula.

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6
Q

What movements does the glenohumeral joint permit?

A
  • extended/flexed in the sagittal plane, abducted 180 degrees or adducted behind the thorax, rotated about its long axis, circumducted - these movements permit the hand to be placed anywhere in a wide cone of space
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7
Q

The articular surface of the head of the humerus forms…

A
  • 2/5ths of a sphere and is considerably larger than the shallow glenoid fossa which faces anteriorly resulting in lots of mobility
  • the femoral head is 2/3 of a sphere
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8
Q

The anatomical neck of the humerus …

A

Separates the tubercles from the head of the humerus so is very short

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9
Q

The surgical neck of the humerus …

A

is the upper end of the shaft beneath the tubercles and is a common site of fracture

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10
Q

The glenoid fossa is…

A

Very shallow and doesn’t hold the entire articular surface of the humerus - it does not HOLD the head of the humerus

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11
Q

The glenoid fossa is surrounded by a …

A

Fibrocartilaginous glenoid labrum that does little to improve the stability of the joint

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12
Q

Where does the joint capsule of the shoulder joint extend from and to?

A

Bone of the scapula around the margins of the labrum to the ANATOMICAL neck of the humerus EXCEPT inferiorly where it is attached to the SURGICAL neck
> the capsule is lax inferiorly to accomodate abduction

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13
Q

Where does the joint capsule not attach to the anatomical neck and why?

A

At the inferior margin where it attaches to the surgical neck - the capsule is lax inferiorly to accomodate abduction

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14
Q

Where is there an opening to the joint capsule and why?

A

There is an opening anteriorly at the joint capsule where the synovial cavity communicates with the subscapularis bursa

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15
Q

What makes the shoulder joint mobile?

A

Glenoid Fossa only holds 1/3 of the articular surface of the humerus (2/5 sphere). Big head and shallow cup results in the fossa not HOLDING the head and permitting lots of movement

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16
Q

Where is the joint capsule of the shoulder thickened?

A

Across the intertubercular groove where it forms the transverse humeral ligament which holds down the tendon of biceps long head

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17
Q

What is the SYNOVIAL capsule of the shoulder joint attached to?

A
  • attached inferiorly and superiorly to the glenoid labrum
  • lines the fibrous capsule and then reflects back on itself to attach to the anatomical head of the humerus at the articular margin
  • communicates with the suprascapular bursa and forms a sleeve for tendon of long head biceps
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18
Q

The long head tendon of biceps is …

A

Intracapsular but extra-synovial

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19
Q

What is the main stabilser of the joint?

A

The capsule itself is lax so it is the rotator cuff muscles that attach to the tubercles and stabilise the joint

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20
Q

The supraglenoid and infraglenoid tubercles are …

A

Intracapsular as they are within the joint space

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21
Q

The articular cavity is …

A

Within the synovial membrane

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22
Q

The synovial membrane does NOT cover the …

A

Cartilage - would be sheared off

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23
Q

What is the advantage of having a loose joint capsule

A

Means it only impedes on the joint at the extreme range of movements

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24
Q

What is the significance of having the fibrous capsule attach back from the articular margin at the surgical neck rather than anatomical?

A

Means there is more movement before it impedes on the movement making it a mobile joint

25
Q

The articular capsule consists of the …. and …

A

Fibrous capsule and synovial membrane

26
Q

Does the shoulder rely on active or passive stablisation?

A

Active (muscle). The capsule is so lax that you could pull it out of the glenoid

27
Q

Are there any intra-capsular ligaments?

A

No unlike in the knee (cruciates)

28
Q

What are the ligaments associated with the shoulder joint?

A
  1. Coracoacromial
  2. Coracoclavicular
  3. Coracohumeral
  4. Glenohumeral (3)
  5. Transverse Humeral
29
Q

What are the extra-capsular ligaments of the shoulder?

A
  1. Coracoacromial

2. Coracoclavicular

30
Q

What are the capsular ligaments of the shoulder?

A
  1. Coracohumeral
  2. Glenohumeral
  3. Transverse Humeral
31
Q

Coracoacromial ligament?

A
  • coracoid to acromion
  • ligament across the same bone?
  • forms superior of the coracoacromial arch
  • prevents superior dislocation of the humerus
32
Q

How strong is the coracoacromial arch?

A

Very - more likely to break your clavicle than the ligament

33
Q

Coracoclavicular Ligament?

A
  • 2 parts; conoid and trapezoid

- passively suspends arm

34
Q

Coracohumeral Ligament?

A
  • is like a continuation of the coracoclavicular
  • greater tubercle to the coracoid
  • is a strong flattened band capable of passively suspending the arm but is lax during abduction
  • means during abduction the joint requires active stabilisation
  • reinforces the capsule superiorly
35
Q

Glenohumeral Ligaments?

A
  • 3 weak thickenings of the anterior and inferior capsule

- this is the weakest part of the capsule and is where most dislocations occur

36
Q

What are the glenohumeral ligaments thickenings of?

A

Anterior inferior capsule

37
Q

Where is the most common site of shoulder dislocation?

A

Anteriorly and inferiorly - this area is only protected by the 3 weak glenohumeral ligaments not muscle like the rest of the capsule

38
Q

Transverse Humeral Ligament?

A
  • GT > LT
  • contains biceps tendon as it emerges from the joint space
  • the Sacciform Synovial Membrane surrounds the tendon under the transverse ligaments and tries to lubricate it and reduce rupture risk
39
Q

Where is the sacciform synovial membrane?

A
  • beneath the transverse humeral ligament around biceps long head tendon
40
Q

How many bursae are there at the shoulder joint?

A

> subdeltoid (continuous with subacromial)

> subscapular (continuous with subcoracoid)

41
Q

Subscapular Bursa?

A
  • found beneath the tendon of subscapularis on anterior humerus
  • this bursa is continues with the joint space due to a hole in the glenohumeral ligaments that allows a bulge of synovial membrane
  • as it is in continuation with joint space it is an avenue for infection
  • it protects the tendon over the lip of the glenoid
42
Q

Subdeltoid Bursa?

A
  • sits under the deltoid over the greater tubercle and the muscles that insert here
  • the subdeltoid bursa prevents impingement of the greater tubercle and the rotator cuff muscle tendons (supra/infraspinatus) on the coracoacromial arch during abduction (is continuous with the subacromial arch)
43
Q

Which bursa is an avenue for infection to the joint space?

A

Subscapular (hole in glenohumeral ligaments makes it continuous with anterior joint space)

44
Q

Describe the arrangement of the rotator cuff muscles on the shoulder

A 
posterior superior = subscapular
anterior
> inferior: teres minor
> middle: infraspinatus
> superior: supraspinatus
45
Q

Significance of biceps being intracapsular?

A

Adds stability to the head of the humerus and provides a line of pull parallel to the axis of the humerus in order to better flex the elbow

46
Q

Purpose of bursa is to …

A

Minimise the friction of tendons as they pass across bone or other tendons

47
Q

What are the rotator cuff muscles?

A
  1. Subscapularis
  2. Supraspinatus
  3. Infraspinatus
  4. Teres Minor
    > the tendons blend with the joint capsule
48
Q

Supraspinatus?

A

O: Subscapular Fossa
I: LESSER tubercle
> internally rotates arm
> Upper and Lower Subscapular Nerve (posterior cord)
> tendon is protected by the subscapular bursa at the neck of the lateral scapula/glenoid

49
Q

Supraspinatus?

A 
O: Supraspinous Fossa
I: Superior facet of greater tubercle 
> Suprascapular Nerve (superior trunk)
> Abducts arm first 15 degrees
> runs beneath the coracoacromial arch so is protected by the subdeltoid/subacromial bursae
50
Q

What are the chief abductors of the arm?

A

Deltoid and supraspinatus

51
Q

Infraspinatus?

A

O: Infraspinous Fossa
I: Middle facet of greater tubercle
> Suprascapular Nerve
> Externally rotates arm

52
Q

Teres Minor?

A

O: Lateral Border of Scapula
I: Inferior facet of greater tubercle
> axillary nerve
> externally rotates arm

53
Q

Purpose of rotator cuff muscles?

A

Compensates for the lax capsule - pulls head of humerus into glenoid via active stabilisation and enables joint to be mobile

54
Q

Teres Major

A 
NOT a rotator cuff muscle
O: Inferior angle of scapula
I: Medial lip of intertubercular groove 
> Lower Subscapular Nerve
> Internally rotates arm
55
Q

What do there teres muscles prevent?

A

Upwards dislocation of the humerus

56
Q

Internal rotators?

A

Pec major, Teres Major, Lat Dorsi, Subscapularis

57
Q

Flex Arm?

A

Clavicular fibres of pec major and the anterior fibres of deltoid (and biceps and coracobrachialis)

58
Q

Extend arm?

A

Posterior deltoid and lat dorsi (and triceps)

59
Q

What is the only muscle that provides support for the head of the humerus inferiorly in abduction?

A

Long head of TRICEPS - this means the joint is weakest in this position and a fall on an outstretched abducted arm can dislocate the head of the humerus inferiorly

MSK (29 decks)

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