Muscles Of The Shoulder And Back (3) Flashcards

0
Q

Which overall group does posterior axio-appendicular muscles belong to?

A
  • Intrinsic
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1
Q

What are the two different overall types of muscles in the back?

A
  • Intrinsic

- Extrinsic

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2
Q

What are the three types of posterior axio-appendicular muscles?

A
  • Superficial group: Trapezius and latissimus dorsi
  • Deep muscles: Levator scapulae and rhomboids
  • Scapulo-humeral: deltoid, teres major and 4 rotator cuff muscles
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3
Q

Where is the trapezius attached and on which joint does it act?

A
  • Direct attachment of pectoral girdle to trunk

- Acts on scapulo-thoracic joint

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4
Q

What three parts are there to the trapezius and what body movements do they allow?

A
  • Superior: elevates scapula (e.g. Shrugging)
  • Middle: retracts scapula (e.g. Squaring of shoulders)
  • Inferior: depresses scapula
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5
Q

How does the scapula rotate?

A
  • Superior and inferior parts of trapezius act together to rotate the scapula upwards and outwards on chest wall (elevating glenoid cavity)
  • Serratus anterior muscle also aids upwards rotation of scapula
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6
Q

What does scapula rotation allow?

A
  • Abduction of arm above horizontal (90 degrees)
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7
Q

Describe the latissimus dorsi.

A
  • Wide origin
  • Narrow insertion
  • Large
  • Fan shaped
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8
Q

What are the attachments for the latissimus dorsi?

A
  • Last 6 thoracic vertebrae
  • Thoracolumbar fascia
  • Iliac crest to floor of intertubercular groove
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9
Q

What body movements is the latissimus dorsi responsible for?

A
  • Powerful adductor of arm at shoulder joint
  • Extends arm at shoulder joint
  • Medial rotator
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10
Q

What nerve supplies the latissimus dorsi?

A
  • Thoraco-dorsal nerve
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11
Q

What is the role of rhomboids major and minor?

A
  • Retracts scapula

- Rotates scapula depressing glenoid cavity

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12
Q

What is the role of levator scapulae muscle?

A
  • Elevates scapula

- Rotates scapula depressing glenoid cavity

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13
Q

Which nerves supply the levator scapulae muscle?

A
  • Dorsal scapula nerve

- Cervical nerve

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14
Q

Which are the scapulo humeral muscles?

A
  • Deltoid
  • Teres major
  • Rotator cuff muscles
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15
Q

What are the three main fibres of the deltoid muscle and what movement do they allow?

A
  • Anterior fibres (clavicular): flexion of arm at SJ
  • Middle fibres (acromial): abducts arm from 15-90 degrees
  • Posterior fibres (spinal): extends arm at SJ
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16
Q

What is the main role of the deltoid?

A
  • Powerful abductor of arm at SJ
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17
Q

What nerve supplies the deltoid?

A
  • Axillary nerve
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18
Q

What is the origin and insertion of the deltoid?

A
  • Anterior, upper surface of the clavicle
  • Acromion
  • Spine of scapula
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19
Q

What is the origin and insertion of the teres major?

A
  • Origin: Inferior angle of scapula

- Insertion: Upper humerus

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20
Q

What is the main actions that the teres major plays a role in?

A
  • Adducts arm

- Medial rotation

21
Q

Which nerve supplies the teres major?

A
  • Lower subscapular nerve
22
Q

Outline the steps to describe a joint.

A
  • Articular surfaces
  • Capsule
  • Ligaments
  • Movements
  • Blood supply
  • Nerve supply
23
Q

What is the shoulder joint also known as?

A
  • Gleno-humeral joint.
24
Q

Describe the Gleno-humeral joint.

A
  • Synovial ball and socket joint
  • Wide range of movements in multiple planes
  • Lined by hyaline cartilage
  • Glenoid cavity is deepened by glenoid labrum (ligament)
25
Q

What is a bursae?

A
  • Small sac with synovial fluid to aid movement.
26
Q

Why is the SJ unstable?

A
  • Glenoid cavity is shallow
  • Disproportionate articular surfaces for joint
  • Loose capsule (lax)
27
Q

What stabilises the SJ?

A
  • Rotator cuff muscles
  • Ligaments
  • Capsule
28
Q

Why is the SJ so unstable?

A
  • Needs to be able to cover multiplanar movement.
29
Q

Where is the glenoid capsule attached to?

A
  • Glenoid labrum and margins of glenoid cavity of scapula

- Anatomical neck of humerus

30
Q

What is the ‘path’ of the capsule?

A
  • Bridges intertubercular groove

- Dips down medially to surgical neck (to provide laxity for full abduction)

31
Q

Why is there a small opening anteriorly in the glenoid cavity?

A
  • So synovial membrane of SJ can communicate with subscapular bursa
32
Q

Describe the synovial membrane’s role in the gleno-humeral joint.

A
  • Synovial membrane lines capsule and bone up to edge of articulating surfaces.
  • Tendon of long head of biceps lies within joint cavity
  • Tubular sleeve of synovium reflects back around bicep’s tendon
  • Synovium and joint cavity is continuous with subscapular bursa via gap in capsule.
33
Q

What components is the extra capsular ligament comprised of?

A
  • Coracoacromial ligament (CAL): between acromion and coracoid process
  • Coracohumeral ligament (CHL): coracoid process to anterior part of greater tubercle
  • Transverse humeral ligament: holds tendon of long head of biceps in place during movement.
34
Q

What is the position and role of the Coracoacromial arch?

A
  • Stong osteoligamentous structure
  • Overlies humeral head
  • Prevents upper displacement of humerus
35
Q

What are the rotator cuff muscles?

A
  • Collective name for 4 short muscles:
  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Subscapularis
36
Q

What are the actions of the individual muscles of the rotator cuff?

A
  • Supraspinatus: initiation and 1st 15 degrees of abduction
  • Infraspinatus: Lateral rotation of the arm
  • Teres minor: Lateral rotation of arm (weak adductor)
  • Subscapularis: medial rotation of arm
37
Q

How do the muscles act as a cuff on the glenoid-humeral joint?

A
  • Tendons blend together to form a cuff
  • Tendinous cuff fuses with capsule
  • Inserted to greater and lesser tubercles close to articular region
  • Tone of the muscles hold them close to the glenoid cavity
  • Supraspinatus tendon’s separated from CAA by subacromial bursa
38
Q

There’s a space between acromion and head of humerus what’s in this space and how large is the space?

A
  • ~1-1.5cm
  • Subacromial bursa
  • Rotator cuff tendons
  • Capsule
  • Tendon of long head of biceps
39
Q

What are the muscles stabilising SJ?

A
  • Deltoid

- Long heads of biceps and triceps

40
Q

What is the role of the subscapular bursa?

A
  • Facilitates movement of tendon of Subscapularis muscle of scapula
  • Communicates with joint cavity
41
Q

What is the role of the subacromial bursa?

A
  • Facilitates movement of supraspinatus tendon under CAA, deltoid muscle over SJ capsule and greater tubercle of humerus
42
Q

What damage to the subacromial bursa may lead to restriction of movement?

A
  • Inflammation of bursa-subacromial bursitis

- Pain on abduction of arm from 15-130 degrees

43
Q

What provides overall stability of the SJ?

A
  • Tendons of rotator cuff
  • Coracoacromial arch (CAA)
  • Gleno-humeral ligaments
  • Coracohumeral ligament
  • Deepening of GC by glenoid labrum
  • Splinting effect of long heads of biceps/triceps
44
Q

Which type of dislocation of the gleno humeral joint is most common and why?

A
  • Anterior
  • As humeral head locates anteriorly due to pull of powerful adductors
  • Humeral head comes to lie below coracoid process
45
Q

Why may an initial dislocation lead to recurrent dislocation?

A
  • Capsule and rotator cuff may tear
  • Poor healing
  • Recurrent dislocation.
46
Q

What nerve may be injured during a dislocation of the shoulder?

A
  • Axillary nerve
47
Q

What signs are there of axillary nerve injury?

A
  • Paralysis of deltoid muscle - loss of abduction

- Loss of sensation in regimental badge area - supplied by lateral cutaneous nerve

48
Q

What problems may tendons of the rotator cuff rubbing under CAA lead to?

A
  • Irritation and inflammation of rotator cuff tendons/SA bursa
  • Subacromial bursitis
  • Supraspinatus tendinitis
  • Rotator cuff injury
  • Degeneration and rupture of tendons
49
Q

What are the risk factors associated with rotator cuff injuries?

A
  • Repetitive overuse - e.g. sporting activities/working involving overhead arms (painter)
  • Old age - degeneration
  • Avascularity of supraspinatus tendon.