Anatomy of the shoulder region Flashcards

1
Q

Skeletal components of the pectoral girdle

A
  • Clavicle

- Scapula

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2
Q

Two key joints in the shoulder

A
  • Glenohumeral joint

- Acromioclavicular joint

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3
Q

Ligaments of the shoulder region

A

Stabilise/support the shoulder region - very strong

  • Coracoclavicular
  • Acromioclavicular
  • Coracoacromial
  • Glenohumeral (superior, middle, inferior)

Attachments are all in the name

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4
Q

Features of coracoclavicular and coracoacromial ligaments

A

Coracoclavicular - two parts, major stabilising ligament

Coracoacromial - forms arch, provides support for head of humerus, prevents superior dislocation

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5
Q

Features of the glenohumeral joint

A

Highly mobile ball and socket joint

  • Abduction/adduction
  • Flexion/extension
  • Lateral/medial rotation
  • Circumduction
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6
Q

Function of the deltoid

A
  • Abduction of the arm
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7
Q

Deltoid - origin

A
  • Spine of scapula + acromion + clavicle
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8
Q

Deltoid - insertion

A
  • Deltoid tuberosity
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9
Q

Innervation of the deltoid

A

Supplied by axillary nerve
Posterior fibres - extension + lateral rotation

Anterior fibres - flexion + medial rotation

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10
Q

Which muscles perform adduction of the arm

A
  • Performed by latissimus dorsi and pectoralis major
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11
Q

Joints involved in abduction/adduction of the arm

A
  • Glenohumeral joint accommodates parts of movement

- Rotation of scapula increases range of movement

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12
Q

Other muscle fibres involved in abduction

A
  • Upper fibres of trapezius
  • Lower fibres of trapezius
  • Serratus anterior (for lateral rotation of scapula)
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13
Q

Other muscle fibres involved in adduction

A
  • Levator scapulae

- Rhomboids

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14
Q

Muscles involved in the flexion of the arm

A
  • Short head of biceps
  • Long head of biceps
  • Coracobrachialis
  • Brachialis - flexes forearm
  • Anterior fibres of deltoid
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15
Q

Muscles involved in extension of arm

A
  • Long head of triceps
  • Lateral head of triceps(extend forearm)
  • Medial head of triceps(extend forearm)
  • Posterior fibres of deltoid
  • Latissimus dorsi
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16
Q

Why is the glenohumeral joint unstable

A
  • Large humeral head
  • Shallow glenoid fossa
  • Most frequently dislocated joint - anterior dislocation common (humeral head descends inferiorly and ends up anterior)
17
Q

Factors which increase glenohumeral joint stability

A
  1. Coracoacromial arch
  2. Glenohumeral ligaments
  3. Deepening of glenoid fossa by glenoid labrum
  4. Long heads of biceps (above) and triceps (below)
  5. Tendons of rotator cuff muscles
18
Q

What does the coracocromial arch prevent

A
  • Prevents superior dislocation
19
Q

What do the glenohumeral ligaments support

A
  • Supports anterior of joint
20
Q

How does the glenoid labrum increase glenohumeral stability

A
  • Deepens glenoid fossa
21
Q

Long head of biceps - origin

A
  • Supraglenoid tubercle

- Long head biceps passes through joint capsule of the transverse humeral ligament

22
Q

Long head of triceps - origin

A
  • Infraglenoid tubercle
23
Q

Features of the rotator cuff muscles

A
  • Four muscles
  • Insert on humerus close to joint
  • Fuse with the joint capsule
  • Forms cuff around joint
24
Q

Which sides do the rotator cuff muscles surround

A
  • Rotator cuff muscles surround on all sides except inferiorly
25
Q

What is the subacromial bursa

A
  • The subacromial bursa is the synovial cavity located just below the acromion, which communicates with the subdeltoid bursa
26
Q

Rotator cuff muscles - insertion

A
  • Supraspinatus, infraspinatus and teres minor insert into the greater tubercle
27
Q

Rotator cuff function

A

Together: stabilise humeral head on glenoid fossa

Supraspinatus - initiate abduction

Infraspinatus - lateral rotation

Teres minor - lateral rotation

Subscapularis - medial rotation

28
Q

Function of teres major

A
  • Should also be considered with the rotator cuff muscles
  • Performs medial rotation
  • Stabilised the humerus during abduction (eccentric contraction)
29
Q

Rotator cuff injuries

A

Supraspinatus impingement:

  • Supraspinatus most commonly injured
  • Limited space for tendon under coracoacromial arch
  • Impingement due to repetitive overhead activities (common in athletes such as throwers)
30
Q

Blood supply to the rotator cuff

A
  • Rich blood supply
  • Scapula anastomosis
  • Allows continuous supply of blood to shoulder region during movement
  • From subclavian and axillary arteries
31
Q

What is the scapular anastomosis(memorise diagram)

A
  • The scapular anastomosis is a system connecting certain subclavian artery and their corresponding axillary artery, forming a circulatory anastomosis around the scapula
  • It allows blood to flow past the joint in case of occlusion, damage, or pinching of specific scapular arteries
32
Q

Nerve supply to the shoulder

A

From the brachial plexus - suprascapular nerve(supraspinatus and infraspinatus)

33
Q

Location of the cords of the brachial plexus

A
  • Within axilla

- Below pectoralis minor

34
Q

Specific innervation of deltoid and teres minor + triceps brachii

A

Posterior cord:
Axillary - deltoid and teres minor
Radial - triceps brachii

35
Q

Specific innervation of subscapularis, teres major and thoracodorsal nerve

A

Upper and lower subscapular nerves - subscapularis, teres major
Thoracodorsal nerve - latissimus dorsi

36
Q

Boundaries of the quadrangular space

A

above/superior: the teres minor (inferior margin).
below/inferior: the teres major (superior margin)
medially: the long head of the triceps brachii (lateral margin)
laterally: the surgical neck of the humerus
anteriorly: the subscapularis

37
Q

What can a fracture of the surgical neck of the humerus result in

A
  • Possible damage to the axillary nerve and posterior circumflex humeral artery
38
Q

Which branch of the lateral cord of the brachial plexus supplies pectoralis major

A
  • Lateral pectoral nerve
39
Q

Branches of the medial cord that innervate pec major and minor

A
  • Medial pectoral nerve (pectoralis major and minor)

- Medial cutaneous nerves to arm and forearm