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[AMS] Musculoskeletal System > S7) The Shoulder > Flashcards

S7) The Shoulder Flashcards

1
Q

There are two types of muscles of the shoulder. Identify and describe them

A

- Extrinsic muscles originate from the torso and attach to the bones of the shoulder (clavicle, scapula or humerus)

- Intrinsic muscles originate from the scapula and/or clavicle and attach to the humerus

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2
Q

Identify the 6 intrinsic muscles of the shoulder

A
  • Deltoid
  • Teres major
  • Supraspinatus
  • Infraspinatus
  • Subscapularis
  • Teres minor
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3
Q

Describe the structure and function of the deltoid muscle

A
  • Structure: consists of anterior, middle and posterior parts

- Action: shoulder flexion (anterior fibres), shoulder extension (posterior fibres), abduction 15-90o (middle fibres)

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4
Q

State the origin and attachment of the deltoid muscle

A
  • Origin: scapula and clavicle
  • Attachment: deltoid tuberosity on lateral surface of the humerus
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5
Q

What innervates the deltoid muscle?

A

Axillary nerve

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6
Q

Describe the structure and function of the teres major muscle

A
  • Structure: forms inferior border of the quadrangular space

- Function: adduction, medial rotation

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7
Q

State the origin and attachment of the teres major muscle

A
  • Origin: posterior surface of the inferior angle of the scapula
  • Attachment: intertubercular groove of the humerus
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8
Q

What innervates the teres major muscle?

A

Lower subscapular nerve

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9
Q

What are the rotator cuff muscles and what do they do?

A
  • The rotator cuff muscles are a group of four muscles that originate from the scapula and attach to the humeral head
  • Collectively, the resting tone of these muscles acts to ‘pull’ the humeral head into the glenoid fossa stabilising the glenohumeral joint
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10
Q

Identify the 4 rotator cuff muscles

A
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11
Q

State the function of supraspinatus muscle

A

Abducts the arm 0-15° and assists deltoid for 15-90°

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12
Q

State the origin and attachment of the supraspinatus muscle

A
  • Origin: supraspinous fossa of the scapula
  • Attachment: greater tubercle of the humerus
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13
Q

What innervates the supraspinatus muscle?

A

Suprascapular nerve

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14
Q

State the function of the infraspinatus muscle

A

Lateral rotation

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15
Q

State the origin and attachment of the infraspinatus muscle

A
  • Origin: infraspinous fossa of the scapula
  • Attachment: greater tubercle of the humerus
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16
Q

What innervates the infraspinatus muscle?

A

Suprascapular nerve

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17
Q

State the function of the subscapularis muscle

A

Medial rotation

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18
Q

State the origin and attachment of the subscapularis muscle

A
  • Origin: subscapular fossa on the costal surface of the scapula
  • Attachment: lesser tubercle of the humerus
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19
Q

What innervates the subscapularis muscle?

A

Upper and lower subscapular nerves

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20
Q

State the function of the teres minor muscle

A

Lateral rotation

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21
Q

State the origin and attachment of the teres minor muscle

A
  • Origin: posterior surface of the scapula
  • Attachment: greater tubercle of the humerus
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22
Q

What innervates the teres minor muscle?

A

Axillary nerve

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23
Q

Where extrinsic muscles of the shoulder found?

A

Extrinsic muscles of the shoulder are located in the back aka. superficial back muscles

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24
Q

Which two muscles are in the superficial layer of the shoulder?

A
  • Trapezius
  • Latissimus Dorsi
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25
Q

Describe the structure and function of the trapezius muscle

A
  • Structure: broad, flat and triangular muscle, most superficial of all the back muscles

- Function: elevate rotates scapula during abduction (upper fibres), retract scapula (middle fibres), pull scapula inferiorly (lower fibres)

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26
Q

State the origin and attachment of the trapezius muscle

A
  • Origin: skull, nuchal ligament and the spinous processes of C7-T12
  • Attachment: clavicle, acromion and the scapula spine
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27
Q

What innervates the trapezius muscle?

A

Accessory nerve

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28
Q

Describe the function of the lattismus dorsi

A
  • Extension
  • Adduction
  • Medial rotation
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29
Q

State the origin and attachment of the lattismus dorsi

A
  • Origin: spinous processes of T6-T12, iliac crest, thoracolumbar fascia and the inferior three ribs
  • Attachment: intertubercular sulcus of the humerus
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30
Q

What innervates the lattismus dorsi?

A

Thoracodorsal nerve

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31
Q

Which three muscles are in the deep layer of the shoulder?

A
  • Levator Scapulae
  • Rhomboid major
  • Rhomboid minor
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32
Q

Describe the structure and function of the levator scapulae

A
  • Structure: small strap-like muscle

- Function: elevates the scapula

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33
Q

State the origin and attachment of the levator scapulae

A
  • Origin: transverse processes of the C1-C4 vertebrae
  • Attachment: medial border of the scapula
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34
Q

What innervates the levator scapulae?

A

Dorsal scapular nerve

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35
Q

State the function of the rhomboid major

A

Retracts and rotates the scapula

36
Q

State the origin and attachment of the rhomboid major

A
  • Origin: spinous processes of T2-T5 vertebrae
  • Attachment: medial border of the scapula
37
Q

What innervates the rhomboid major?

A

Dorsal scapular nerve

38
Q

State the function of the rhomboid minor

A

Retracts and rotates the scapula

39
Q

State the origin and attachment of the rhomboid minor

A
  • Origin: spinous processes of C7-T1 vertebrae
  • Attachment: medial border of the scapula
40
Q

What innervates the rhomboid minor?

A

Dorsal scapular nerve

41
Q

Describe the division of the back muscles

A

The muscles of the back can be divided into three groups – superficial, intermediate and deep:

  • Superficial – associated with movements of the shoulder
  • Intermediate – associated with movements of the thoracic cage
  • Deep – associated with movements of the vertebral column
42
Q

Compare and contrast and describe the development the muscles of the back

A
  • The deep muscles develop embryologically in the back, and are thus described as intrinsic muscles
  • The superficial and intermediate muscles do not develop in the back, and are classified as extrinsic muscles
43
Q

What is the shoulder joint?

A
  • The shoulder joint (glenohumeral joint) is a ball and socket joint between the scapula and the humerus
  • It is the major joint connecting the upper limb to the trunk
  • It is one of the most mobile joints in the human body, at the cost of joint stability
44
Q

Describe the formation of the shoulder joint

A

The shoulder joint is formed by the articulation of the head of the humerus with the glenoid cavity (or fossa) of the scapula

45
Q

What covers the articulating surfaces of the shoulder joint?

A

Both the articulating surfaces are covered with hyaline cartilage

46
Q

What makes the shoulder joint unstable and which structure tackles this?

A
  • The head of the humerus is much larger than the glenoid fossa
  • Glenoid fossa is deepened by a fibrocartilage rim, the glenoid labrum, to provide more stability
47
Q

Describe the structure, function and location of the joint capsule in the shoulder

A
  • Structure: fibrous sheath, lax to permit greater mobility
  • Function: encloses the structures of the joint
  • Location: extends from the anatomical neck of the humerus to the border of the glenoid fossa
48
Q

What is a synovial membrane and what does it do?

A

The synovial membrane lines the inner surface of the joint capsule, and produces synovial fluid to reduce friction between the articular surfaces

49
Q

What is a bursa?

A

A bursa is a synovial fluid filled sac, which acts as a cushion between tendons and other joint structures and reduces friction

50
Q

Identify and describe the bursae in the shoulder of clinical importance

A
  • Subacromial bursa is located inferiorly to the deltoid and acromion, and superiorly to the supraspinatus tendon and the joint capsule

- Subscapular bursa is located between the subscapularis tendon and the scapula

51
Q

Describe the structure and function of the ligaments in the shoulder joint

A
  • Structure: thickenings of the joint capsule
  • Function: stabilise the bony structures of the shoulder joint
52
Q

Identify the 3 key ligaments in the shoulder joint

A
  • Glenohumeral ligaments (superior, middle and inferior)
  • Coracohumeral ligament
  • Transverse humeral ligament
53
Q

Describe the location and function of the glenohumeral ligaments of the shoulder

A
  • Location: three bands which run with the joint capsule from the glenoid fossa to the anatomical neck of the humerus
  • Function: stabilise the anterior aspect of the joint
54
Q

Describe the location and function of the coracohumeral ligament of the shoulder

A
  • Location: attaches the base of the coracoid process to the greater tubercle of the humerus
  • Function: supports the superior part of the joint capsule
55
Q

Describe the location and function of the transverse humeral ligament of the shoulder

A
  • Location: spans the distance between the two tubercles of the humerus
  • Function: holds the tendon of the long head of the biceps in the intertubercular groove
56
Q

The other major ligament of the shoulder is the coracoacromial ligament.

Describe its structure, function and location of this ligament

A
  • Structure: not a thickening of the joint capsule
  • Function: overlies the shoulder joint, preventing superior displacement of the humeral head
  • Location: runs between the acromion and coracoid process of the scapula, forming the coraco-acromial arch
57
Q

Describe the neurovascular supply of the shoulder joint

A
  • Arterial supply via the anterior and posterior circumflex humeral arteries, and the suprascapular artery
  • Innervated by the axillary, suprascapular and lateral pectoral nerves
58
Q

Identify the 6 primary movements of the shoulder joint

A
  • Extension
  • Flexion
  • Abduction
  • Adduction
  • Medial Rotation
  • Lateral Rotation
59
Q

Identify the muscles involved in the flexion and extension of the shoulder joint

A
  • Extension is produced by the posterior deltoid, latissimus dorsi and teres major

- Flexion is produced by the biceps brachii, pectoralis major, anterior deltoid and coracobrachialis

60
Q

Identify the muscles involved in the abduction and adduction of the shoulder joint

A
  • Abduction is produced by the supraspinatus (0-15o), middle deltoid (15-90o), trapezius and serratus anterior (>90o)

- Adduction is produced by the pectoralis major, latissimus dorsi and teres major

61
Q

Identify the muscles involved in the medial and lateral rotation of the shoulder joint

A
  • Medial rotation is produced by the subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid

- Lateral Rotation is produced by the infraspinatus and teres minor

62
Q

Identify 3 factors that contribute to the mobility of the shoulder joint

A
  • Nature of joint (ball and socket joint)

- Bony surfaces (shallow glenoid cavity and large humeral head)

  • Laxity of the joint capsule
63
Q

Identify 3 factors that contribute to the stability of the shoulder joint

A
  • Rotator cuff muscles
  • Glenoid labrum
  • Ligaments
64
Q

Describe the structure and function of the scapula

A
  • Structure: triangular, flat bone, attachment site for 17 muscles
  • Function: articulates with the humerus at the glenohumeral joint and with the clavicle at the acromioclavicular joint, to connect the upper limb to the trunk
65
Q

Identify the key anatomical features visible on the anterior view (costal surface) of the scapula

66
Q

Identify the key anatomical features visible on the posterior view of the scapula

67
Q

Identify the key anatomical features visible on the lateral view of the scapula

68
Q

Describe the structure and location of the clavicle

A
  • Structure: slender bone, medial aspect is convex, lateral aspect is concave
  • Location: extends between the sternum and the acromion of the scapula
69
Q

The clavicle has three main functions.

Identify them

A
  • Attaches the upper limb to the trunk
  • Protects the underlying neurovascular structures supplying the upper limb
  • Transmits force from the upper limb to the axial skeleton
70
Q

Divide the clavicle into 3 parts

71
Q

Describe the structure and function of the sternal end of the clavicle

A
  • Structure: inferior surface is marked by a rough oval depression for the costoclavicular ligament
  • Function: contains large facet for articulation with the manubrium of the sternum at the sternoclavicular joint
72
Q

Describe the structure and function of the shaft of the clavicle

A
  • Structure: contains a groove for attachment of subclavius
  • Function: acts a point of origin and attachment for several muscles (deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid)
73
Q

Describe the structure and function of the acromial end of the clavicle

A
  • Structure: conoid tubercle attaches conoid ligament (medial part of coracoclavicular ligament), trapezoid line attaches trapezoid ligament (lateral part of coracoclavicular ligament)
  • Function: contains small facet for articulation with the acromion of the scapula at the acromioclavicular joint
74
Q

What is a traumatic anterior shoulder dislocation?

A

An anterior shoulder dislocation is a clinical condition in which the humeral head is displaced anteriorly in relation to the glenoid fossa

75
Q

Anterior shoulder dislocations account for as many as 95-98% of shoulder dislocations.

Why is this?

A

Muscular and ligamentous support anterior to the humeral head is much less robust than the posterior aspect with the rotator cuff and scapula

76
Q

What is a traumatic posterior shoulder dislocation?

A

An posterior shoulder dislocation is a clinical condition in which the humeral head is displaced posteriorly in relation to the glenoid fossa

77
Q

Due to low levels of clinical suspicion and insufficient imaging, posterior shoulder dislocations are often missed.

Identify 2 causes

A
  • Electric shock
  • Seizure
78
Q

How many different ways can the acromioclavicular joint be dislocated?

A

Acromioclavicular joint has six different ways of dislocating

79
Q

The clavicle is the most commonly fractured bone in the body.

How do these fractures occur?

A
  • Falling onto the shoulder
  • Falling onto an outstretched hand
80
Q

The most common point of fracture is the junction of the medial 2/3 and lateral 1/3.

Describe the displacement of the different ends of the clavicle

A
  • Lateral end is displaced inferiorly by the weight of the arm, and medially by the pectoralis major
  • Medial end is displaces superiorly by the sternocleidomastoid muscle
81
Q

Describe how clavicle fractures present

A
  • Suprascapular nerves may be damaged by the upwards movement of the medial end of clavicle
  • Lateral rotators of the upper limb are paralysed so unopposed medial rotation of the upper limb presents as ‘waiters tip’
82
Q

What is rotator cuff tendonitis?

A
  • Rotator cuff tendonitis is the inflammation of the tendons of the rotator cuff muscles, usually occurring secondary to repetitive use of the shoulder joint
  • Degenerative changes occur in the subacromial bursa and supraspinatus tendon, increasing friction between the structures of the joint
83
Q

How does rotator cuff tendonitis present?

A

The characteristic sign of rotator cuff tendonitis is the ‘painful arc’– pain in the middle of abduction, where the affected area comes into contact with the acromion

84
Q

The most common cause of accessory nerve damage is iatrogenic.

Identify medical procedures which might cause trauma to this nerve

A
  • Cervical lymph node biopsy
  • Cannulation of the internal jugular vein
85
Q

How can the accessory nerve function be tested?

A

Trapezius function can be assessed – patient should to shrug his/her shoulders

[AMS] Musculoskeletal System (24 decks)

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