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ESA 2 > MSK 3d: shoulder > Flashcards

MSK 3d: shoulder Flashcards

1
Q

Articulating surfaces of shoulder?

A

Head of humerus into glenoid cavity of scapula- 4:1 disproportion of suraces (very mobile but not stable)
Both surfaces covered in hyaline cartilage
Glenoid cavity deepened slightly by a fibrocartilage rim-glenoid labrum

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2
Q

How is stability of the shoulder achieved?

A

Rotator cuff muscles (most important)
Other muscles
Ligaments
Joint capsule

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3
Q

Joint capsule of shoulder?

A

Attached to glenoid labrum and anatomical neck of humerus. Bridges the intertubecular groove. Superiorly starts at root of coracoid process
Fibrous sheath
Tough but lax to allow movement:
-surgical neck dips down medially to provide laxity for full ABduction
Openings:
-intertubercular groove for tendon of long head of biceps brachii
-anteriorly, inf to CP, small opening where synovial membrane communicates with subscapular bursa

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4
Q

Where is the weakest part of the shoulder joint capsule?

A

Inferior

Because not enclosed by rotator cuff muscles. Particularly lax when the arm is ADducted

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5
Q

Synovial membrane of the glenohumeral joint?

A

Lines internal surface of fibrous layer of capsule, and the bone within the capsule up to the edge of articulating surgaces
Tendon of long head of BB has a tubular sleeve of synovium as it enters the joint to allow it to move freely
Synovium and joint cavity continuous with subscapular bursa via gap in capsule

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6
Q

Extracapsular ligaments of the shoulder?

A
  1. CORACOACROMIAL LIGAMENT most important. Between acromion and coracoid process. Prevents superior dislocation of humeral head
  2. CORACOHUMERAL LIGAMENT. Base of coracoid process to anterior greater tubercle. Strengthens superiorly
  3. TRANSVERSE HUMERAL LIGAMENT. Hold tendon of BB in place during shoulder movement, bridges intertubecular groove from greater to lesser tubercle
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7
Q

Intracapsular ligaments of the shoulder?

A

3 x GLENOHUMERAL LIGAMENTS (superior, middle, inferior)
Fibrous bands extending between glenoid labrum and anatomical neck of humerus. Form part of the fibrous capsule, and reinforce the capsule anteriorly.
Can only be seen from inside the capsule

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8
Q

What is the coraco-acromial arch, and what is its significance?

A

Coracoacromial ligament + acromion + coracoid process (strong as osseoligamentous)

Overlies the humeral head, preventing its superior displacement. Clinically relevant in painful arc syndrome
Tendon of supraspinatous passes underneath

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9
Q

What are the rotator cuff muscles? State their origins and insertions

A

SUPRASPINATOUS: O- supraspinous fossa, I-greater tubercle
INFRASPINATOUS: O-infraspinous fossa, I-greater tubercle
TERES MINOR: O-posterolateral surface of scapula, I-greater tubercle
SUBSCAPULARIS: O: ventral scapula, I-lesser tubercle

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10
Q

Function of the rotator cuff muscles?

A

Tendons blend to form a cuff, which fuses with the capsule and strengthens it
Tone in the muscles holds the head close to the glenoid cavity. Supraspinatous tendon is separated from the CAA by the subacromial bursa

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11
Q

Actions, innervations and nerve roots of rotator cuff muscles?

A

Supraspinatous: first 15 deg of ABduction. Suprascapular nerve (C5,6)
Infraspinatous: lateral rotation. Suprascapular nerve (C5,6)
Teres minor: lateral rotation and weak ADduction. Axillary nerve (C5,6)
Subscapularis: medial rotation. Upper and lower subscapular nerves (C5,6)

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12
Q

Which other muscles stabilise the shoulder?

A

Deltoid
Long head of biceps
Long head of tricpes (attached to infraglenoid tubercle)

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13
Q

What lies in the 1.5cm space between the acromion and head of humerus, and the clinical relevance?

A

Subacromial bursa
Rotator cuff tendons
Capsule
Tendon of long head of BB

During ABduction there’s a risk of soft tissue impingement between the acromion and head of humerus

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14
Q

Subacromial bursa?

A

Inferior to deltoid and acromion, superior to joint capsule & supraspinatous tendon.
Helps movement of:
-supraspinatous tendon under CAA
-deltoid muscle over the joint capsule and greater tubercle

Inflammation-subacromial bursitis-leads to painful arc syndrome (pain on abduction between 50-130 deg)

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15
Q

Subscapular bursa?

A

Allows movement between subscapularis tendon and neck of scapula, and reduces wear and tear on the tendon
Communicates with the joint cavity via an anterior opening in the fibrous capsule

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16
Q

From where does movement of the shoulder originate?

A

Glenohumeral joint
and
Scapulothoracic joint: not actually a joint but scapula moves over thorax as if it were. Mainly in adduction and abduction

17
Q

What produces flexion at the glenohumeral joint?

A

Pec major (clavicular head)
Deltoid (ant fibres)
Coracobrachialis
Biceps brachii

18
Q

What produces extension at the glenohumeral joint?

A

Deltoid (post fibres)
Latissimus dorsi
Teres major

19
Q

What produces ABduction at the glenohumeral joint?

A

0-15 deg-supraspinatous
15-90 deg-deltoid (central fibres)
Above 90 deg-rotation. By trapezius and serratus anterior

20
Q

What produces ADduction at the glenohumeral joint?

A

Pec major
Latissimus dorsi
Teres major

21
Q

What produces medial rotation at the glenohumeral joint?

A

Subscapularis
Teres major
Pec major
Latissimus dorsi

22
Q

What produces lateral rotation at the glenohumeral joint?

A

Infraspinatous

Teres minor

23
Q

Describe the arterial supply of the shoulder

A

Anterior and posterior circumflex arteries (form a network of branches surrounding joint)
Suprascapular artery

24
Q

Describe the nerve supply to the shoulder

A

Suprascapular
Axillary
Lateral pectoral

All roots C5-6

25
Q

Clinical features of painful arc syndrome?

A

Pathogenesis: supraspinatous tendon rubs under CAA, inflammation of supraspinatous tendon and subacromial bursa. Leads to subacromial bursistis, supraspinatous tendonitis, tendon rupture

Risk factors: repetitive overuse (e.g. racquet sports), elderly degenerative changes, avascularity of supraspinatous tendon

Syndrome effects: impinged rotator cuff tendons or inflamed subacromial bursa. On ABduction, very painful between 50-130 deg

26
Q

Describe an anterior dislocation of the glenohumeral joint (caused by trauma onto a fully ABducted arm)

A

Dislocates inferiorly; classified as anterior because humeral head locates anteriorly due to the pull of powerful adductors. Humeral head comes to lie below the coracoid process

Appearance: loss of round contour of affected shoulder, arm supported by other hand as very painful

Recurrent dislocation if capsule and rotator cuff tea

27
Q

How might an axillary nerve injury be caused?

A

Dislocation

Fracture of surgical neck of humerus

28
Q

How would you test for axillary nerve injury?

A

Loss of sensation over regimental badge area over central part of deltoid (as supplied by upper lateral cutaneous nerve)
DO NOT test motor function (deltoid: abduction) as could cause more soft tissue/nerve damage

29
Q

State the muscles within the 3 groups of back muscles

A
  1. Superficial: trapezius and lat dorsi
  2. Deep: levator scapulae and rhomboids
  3. Scapulo-humeral: deltoid, teres major and rotator cuff
30
Q

Trapezius muscle?

A

Direct attachment of pectoral girdle to trunk, acts on scapulothoracic joint. Attaches to the lateral 1/3 of the clavicle, acromion and the spine of the scapula
Superior part-elevates scapula (shrugging)
Middle part-retracts scapula
Inferior part-depresses scapula

Nerve: accessory nerve (CN XI)

31
Q

Describe the muscles involved in rotation of the scapula

A

Superior and inferior parts of trapezius rotate scapula upwards on chest wall (elevating glenoid cavity)
Serratus anterior aids upwards rotation

32
Q

Latissumus dorsi?

A

Large, fan shaped muscle with a wide origin and narrow insertion
O: lower thoracic vertebrae, thoracolumbar fasica and iliac crest
I: floor of intertubecular groove
N: thoracodorsal nerve (post. cord; C6-8)
A: ADduction of arm, extends arm, medial rotation

33
Q

Levator scapulae?

A

O: vertebrae
I: medial border of scapula superior to spine
N: dorsal scapular (C4,5) and cervical nerves
A: elevation, rotates scapula (depressing glenoid cavity)

34
Q

Rhomboids major and minor?

A 
Minor smaller but lies superior to major
O: vertebrae
I: scapula spine
N: dorsal scapular nerve (C5)
A: retracts and rotates scapula (depresses glenoid cavity)
35
Q

Deltoid?

A

O: lat. 1/3 of clavicle, acromion and scapula spine
I: deltoid tuberosity of humerus
N: axillary (C5,6)
A: anterior fibres flex, middle fibres ABduct 15-90 deg, post fibres extend

36
Q

Teres major?

A

O: inferior angle of scapula
I: upper humerus
N: lower subscapular (C5,6)
A: ADducts arm, medially rotates

ESA 2 (58 decks)

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