L3 - Anatomy of the shoulder region Flashcards

1
Q

What is the pectoral girdle?

A

The clavicle & scapula

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2
Q

What are the skeletal components of the shoulder region?

A

Clavicle
Scapula
Humerus

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3
Q

What are the two joints in the shoulder region?

A

Glenohumeral joint

Acromioclavicular joint

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4
Q

What is the function of the ligaments of the shoulder

A

To stabilise/support the shoulder (they are very strong)

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5
Q

What are the ligaments of the shoulder?

A

Coracoclavicular
Acromioclavicular
Coracoacromial
Glenohumeral

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6
Q

How many parts to the coracoclavicular ligament?

A

Two

Sit at right angles to each other - provides added strength

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7
Q

What is important about the coracoclavicular ligament?

A

It is a major stabilising ligament of the shoulder

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8
Q

What is the function of the coracoacromial ligament?

A

Forms an arch
Provides support for the head of the humerus
Prevents superior dislocation of the humerus from the glenohumeral joint

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9
Q

Which ligaments form a triangle?

A

Coracoclavicular and coracoacromial

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10
Q

Which muscle performs abduction of the arm?

A

The deltoid (but supraspinatus initiates it)

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11
Q

Describe the shape and composition of the deltoid muscle

A

Large triangular muscle

Anterior, intermediate and posterior fibres

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12
Q

When the fibres all contract together what happens?

A

Abduction of the arm

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13
Q

Which muscles perform adduction of the arm?

A

Latissimus dorsi

Pectoralis major

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14
Q

What is the origin and insertion of latissimus dorsi?

A

Origin: Thoracolumbar fascia
Insertion: floor of the bicipital groove

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15
Q

What is the origin and insertion of pec major?

A

Origin: sternum & medial clavicle
Insertion: Lateral lip of the bicipital groove

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16
Q

What increases the range of movement in abduction/adduction of the arm?

A

Rotation of the scapula

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17
Q

During abduction of the arm, the inferior angle of the scapula rotates in which direction?

A

Laterally

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18
Q

During adduction of the arm, the inferior angle of the scapula rotates in which direction?

A

Medially

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19
Q

When we raise our arms above our heads the supraglenoid fossa is brought into which position?

A

Superior orientation

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20
Q

What is the composition of the trapezius?

A

Upper, middle and lower fibres

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21
Q

Where do the upper fibres insert?

A

Acromion

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22
Q

Which muscles contract in order to (abduct &) lift our arms up above our head?

A

Upper and lower fibres of the trapezius

Inferior digitations of serratus anterior

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23
Q

Which muscles are involved in adducting the arms?

A

None - adduction of arm mostly due to gravity

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24
Q

Which muscles contract in adduction of the arm against gravity (to bring arms towards horizontal from above our heads)?

A

Levator scapulae

Rhomboid

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25
Q

Which muscles are involved in flexion of the arm?

A

Biceps brachii

Anterior fibres of the deltoid

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26
Q

Describe the composition of the biceps brachii

A

Long head and short head

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27
Q

What is the origin of the long head of the biceps brachii?

A

Supraglenoid tubercle of scapula (at the top of the glenoid fossa)

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28
Q

What is the origin of the short head of the biceps brachii?

A

Apex of coracoid process

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29
Q

What movement does the coracobrachialis help with?

A

Bringing the arm across the torso

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30
Q

What muscle extends the arm?

A

Triceps brachii

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31
Q

What is the composition of the triceps brachii?

A

Long, lateral and medial heads

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32
Q

What is the origin of each head of triceps brachii?

A

Long head: infraglenoid tubercle of scapula
Medial head: posterior surface of shaft of humerus
Lateral head: posterior surface of shaft of humerus

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33
Q

What is the insertion of all heads of the triceps brachii?

A

Olecranon

34
Q

What is the insertion of biceps brachii heads?

A

Radial tuberosity

35
Q

The lateral and medial heads of the triceps brachii have nothing to do with the shoulder, their sole purpose is to:

A

Extend the arm at the elbow

36
Q

Why is the glenohumeral joint hugely unstable?

A

Large humeral head

Shallow glenoid fossa

37
Q

Which is the mostly frequently dislocated joint?

A

Glenohumeral joint

38
Q

What dislocation of the glenohumeral joint is common?

A

Anterior dislocation - humeral head descends inferiorly and ends up anterior

39
Q

Name the soft tissue structures whose function it is to prevent dislocation of the shoulder joint?

A
  1. Coracoacromial arch
  2. Glenohumeral ligaments
  3. Deepening of the glenoid fossa by the glenoid labrum
  4. Long heads of biceps (above) and triceps (below)
  5. Tendons of rotator cuff muscles
40
Q

The coracoacromial arch is formed by which ligament?

A

Coracoacromial ligament

41
Q

Why is the coracoacromial arch important?

A

It forms the void for the head of the humerus & prevents SUPERIOR DISLOCATION of glenohumeral joint

42
Q

How many glenohumeral ligaments are there and what is their function?

A

Three: superior, middle & inferior

To support the anterior of the glenohumeral joint

43
Q

Function of the glenoid labrum?

A

Deepens the glenoid fossa by increasing surface area and providing a more snug fit for the head of the humerus to reduce risk of injury

44
Q

What is the TRANSVERSE HUMERAL LIGAMENT?

A

Covers the bicipital groove
Tendon of the long head of biceps brachii goes through the bicipital groove
THL prevents the tendon of biceps brachii slipping out

45
Q

How many rotator cuff muscles are there?

A
Four: 
Supraspinatus 
Infraspinatus 
Subscapularis 
Teres minor
46
Q

What is the function of the rotator cuff muscles?

A

Fuse with the joint capsule

Form a cuff around the joint and stabilise it

47
Q

Where do the rotator cuff muscles insert?

A

Proximal end of the humerus close to joint

48
Q

The rotator cuff muscles surround the joint on all sides except:

A

Inferiorly - this is why anterior dislocation is most common

49
Q

Where does the tendon of the supraspinatus pass?

A

Superiorly over the joint

50
Q

Where does the tendon of the infraspinatus and teres minor pass?

A

Posteriorly to the joint

51
Q

What is the function of the bursa?

A

They protect the tendon they sit above

52
Q

The tendon of the subscapularis passes?

A

Anteriorly to the joint

53
Q

Where does the subacromial bursa sit?

A

Above the infraspinatus tendon

54
Q

Where does the axillary nerve pass through?

A

Quandrangular space, below teres minor and around the surgical head of the humerus

55
Q

What are the three facets of the greater tubercle and what inserts on these?

A

Uppermost facet: Supraspinatous inserts
Middle facet: Infraspinatous inserts
Lowest facet: Teres minor inserts

56
Q

What is the function of the rotator cuff muscles?

A

Together stabilise the head of the humerus on the glenoid fossa

57
Q

Tonic contraction of all the rotator cuff muscles forces…?

A

Forces the head of the humerus against the glenoid fossa

58
Q

Abduction of the arm by contraction of the deltoid occurs best when there is already a 15 degrees angle away from the body - which is achieved through contraction of which muscle?

A

Supraspinatus

59
Q

Subscapularis contraction leads to which movement?

A

Medial rotation of the scapula

60
Q

Teres major is not a true rotator cuff muscle - true or false?

A

True

61
Q

Teres major performs which action?

A

Medial rotation of the scapula

62
Q

Teres major contracts against which muscle in abduction and why?

A

Deltoid

TM stabilises humerus during abduction

63
Q

What is the blood supply to the rotator cuff muscles?

A

Provided by the scapular anastomosis

64
Q

Which arteries contribute to the scapular anastomosis?

A

Suprascapular & dorsal scapular arteries - branches of the subclavian arteries
Subscapular - branch of the axillary artery

65
Q

What is the significance of the scapula anastomosis?

A

Allows continuous supply of blood to the shoulder region during movement

66
Q

What is the most common rotator cuff injury?

A

Supraspinatus impingement

67
Q

Why is supraspinatus impingement the most common RC injury?

A

Because there is limited space for the supraspinatus tendon below the coracoacromial arch

68
Q

When does impingement of the supraspinatus tendon occur?

A

Due to repetitive overhead activities & when doing the front crawl - common in athletes (throwers)

69
Q

Where does the nerve supply to the shoulder come from?

A

Brachial plexus

70
Q

Which cord is the main nerve supplying the shoulder region?

A

Posterior cord of brachial plexus

71
Q

What does the posterior cord terminate as?

A

Axillary and radial nerves

72
Q

Which muscles are supplied by the axillary nerve?

A

Deltoid

Teres minor

73
Q

Which muscles are supplied by the radial nerve?

A

Triceps brachii

74
Q

Which muscles are supplied by the upper and lower sub scapular nerves?

A

Subscapularis

Teres major

75
Q

The upper and lower sub scapular nerves come off which cord?

A

Posterior cord

76
Q

Damage to the axillary nerve results in?

A

Loss of sensation to the lateral aspect of the arm

May not be able to abduct arm because axillary nerve supplies the deltoid muscle

77
Q

The medial pectoral nerve is branch from which cord?

A

Medial cord

78
Q

The medial cutaneous nerves are branches from which cord?

A

Medial cord

79
Q

The medial cutaneous nerves supply which side of the upper limb?

A

Medial side of arm and forearm

80
Q

The lateral cord terminates as?

A

Musculocutaneous nerve

Lateral part of Median nerve

81
Q

The medial cord terminates as?

A

Medial part of Median nerve

Ulnar nerve