MSK Session 3 (Lecture 3.2)

Question 1

What are the two groups of muscles of the back?

Answer 1

Intrinsic and extrinsic

Question 2

What can extrinsic back muscles be divided into?

Answer 2

Superficial and intermediate groups

Question 3

What do the posterior axio-appendicular muscles do?

Answer 3

Attach the upper limb to the trunk

Question 4

What are the three groups of AAMs? Give examples of each.

Answer 4

1) Superficial - trapezius & Latissimus dorsi
2) Deep - levator scapulae & rhomboids
3) Scapulo-humeral : deltoid, teres major & 4 rotator cuff

Question 5

What nerve innvervates the trapezius muscle?

Answer 5

Accessory

Question 6

Describe the anatomy & function of the trapezius muscle. (3 points)

Answer 6

1) Direct attachemnt of pectoral girdle to trunk
2) Act on scapulothoracic joint

3) Divided into 3 parts :
Superior (elevates scapula)
Middle (retracts scapula)
Inferior (depresses scapula)

Question 7

What nerve innervates the Latissimus dorsi and where does it originate from?

Answer 7

Thoraco-dorsal nerve

From posterior cord of brachial plexus

Question 8

Describe the anatomy & function of the latissimus dorsi muscle. (3 points)

Answer 8

1) Large, fan shaped with a wide origin and narrow insertion
2) Extends from: lower thoracic vertebrae, thoracolumbar fascia & iliac crest to floor of intertubecular groove.
3) Powerful adductor of arm, extends arm at shoulder and medial rotator

Question 9

Which nerves innervate the levator scapulae muscle?

Answer 9

Dorsal scapular & Cervical

Question 10

Describe the anatomy & function of the levator scapulae muscle (2 points)

Answer 10

1) Elevates scapula

2) Rotates scapula depression GC

Question 11

Which nerve innervates the rhomboids major and minor and where does it come from?

Answer 11

Dorsal scapular (C5 root of BP)

Question 12

Describe the anatomy & function of the rhomboids muscle. (3 points)

Answer 12

1) Attaches at the medial border of scapula.
2) Retracts scapula
3) Rotates scapula depressing GC (medial rotation?)

Question 13

Describe the anatomy & function of the deltoid muscle. (2 points). What nerve supplies this muscle?

Answer 13

1) Axillary nerve
2) Inserts in the deltoid tuberosity

3) Anterior fibres (clavicular) = flexion of arm
Middle fibres (acromial) = abducts arm from 15-90 degrees

Question 14

Describe the anatomy & function of the teres major muscle. (2 points) What nerve supplies this muscle?

Answer 14

1) Lower subscapular
2) From inferior angle of scapula to upper humerus
3) Medial rotator and adductor of arm

Question 15

What is a bursa(e)?

Answer 15

Small sacs filled with synovial fluid. Lined by synovium reducing friction upon movement.

Question 16

Where does the shoulder joint move?

Answer 16

1) Glenohumeral and 2) Scapulothoracic (2:1)

Question 17

Describe the articulating surfaces at the GH joint.

Answer 17

1) Head of humerus
2) Glenoid cavity of scapula
3) Lined by HC
4) 4:1 area disproportion
5) Glenoid cavity deepened by glenoid labrum

Question 18

Why is the SJ unstable?

Answer 18

1) GC shallow
2) Disporportion of articular surfaces
3) Multiplanar movements
4) Lax capsule

Question 19

How is stability achieved at the SJ?

Answer 19

1) Rotator cuff (most important)
2) Other muscles
3) Ligaments
4) Capusle

Question 20

Describe the anatomy of the capsule.

Answer 20

1) Attached to : Glenoid labrum + margins of GC of scapula, anatomical neck of humerus
2) Bridges ITG, dips down medially to surgical neck (provides lax for full abduction)
3) Small opening anteriorly (where synovium communicates with subscapular bursa)

Question 21

Describe the anatomy of the synovium at the SJ (4 points)

Answer 21

1) Synovium lines capsule + bone upto edge of articulating surfaces
2) Tendon of long head of biceps brachii lies within joint cavity (attached to supra glenoid tubercule of scapula)
3) Tubular sleeve of synovium refelcted back around biceps tendon like a tube
4) Synovium + joint cavity is continuous with subscapular bursa through a gap in the capsule.

Question 22

What are the three inctracapsular ligaments?

Answer 22

1) Superior, middle and inferior

Question 23

Describe the intracapsular ligaments.

Answer 23

1) 3 fibrous bands extending between glenoid labrum & humerus
2) Part of the fibrous capsule & reinforces capsule anteriorly

Question 24

What are the three extracapsular ligaments?

Answer 24

1) Coracoacromial, coracohumeral, transverse humeral

Question 25

Describe the extracapsular ligaments.

Answer 25

1) CAL : most important 2) CHL : Base of coracoid process to anterior part of greater tubercule 3) THL : holds tendon of long head of biceps in place during shoulder movement.

Question 26

What is the CAA? Describe it.

Answer 26

Coracoacromial arch = CAL + Acromion + coracoid process Strong osseoligamentous structure Overlies humeral head Prevents its upper displacement of humerus Clinically important in the 'painful arc' syndrome

Question 27

What are the muscles of the rotator cuff and where they are inserted?

Answer 27

1) Supraspinatus - greater tubercle 2) Infraspinatus - " 3) Teres minor - " 4) Subscapularis - lesser tubercule

Question 28

What are the actions of the RC muscles?

Answer 28

1) Supraspinatus - initiation and first 15 degrees of abduction 2) Infraspinatus - lateral rotation of the arm 3) Teres minor - lateral rotation of the arm, weak adductor 4) Subscapularis - medial rotation of the arm

Question 29

Which nerves innervate the RC muscles?

Answer 29

1) and 2) - Suprascapular , C5+6 3) Axiallry 4) Upper and lower subscapular

Question 30

What is the tendinous cuff?

Answer 30

Tendons of muscles blend to form a cuff which fuses with a capsule therefore strengthening it.

Question 31

What lies within the space between the acromion and head of humerus? When are these at risk of impingement?

Answer 31

1) Subacromial bursa 2) RC tendons 3) Capsule 4) Tendon of long head of biceps During abduction

Question 32

Where is the long head of triceps attached to?

Answer 32

Infra glenoid tubercule

Question 33

What are the two bursa around the GHJ?

Answer 33

1) Subscapular - facilitates movement of tendon of SSC muscle over scapula 2) Subacromial - facilitates movement of SSP tendon under CAA + deltoid muscle over SJ capsule + greater tubercule of humerus

Question 34

What is painful arc syndrome?

Answer 34

SSP tendon rubbing under CAA Inflammation of bursa causing subacromial bursitis - causes pain on abduction of the arm between 50-130 degrees OR Impingement of inflamed RC tendons Causes subacromial bursitis Supraspinatus tendonitis Degen + rupture of tendons

Question 35

Which people are predisposed to acquiring PAS?

Answer 35

1) Repetitive overuse e.g. sporting activities, painter 2) Older people Avascularity of SSP tendon

Question 36

In which direction is the GHJ dislocated?

Answer 36

Inferiorly

Question 37

How is a GHJ dislocated?

Answer 37

Trauma on a fully abducted arm

Question 38

How is a GHJ defined clinically?

Answer 38

Anterior dislocation because the humeral head located anteriorly, due to pull of adductors.

Question 39

How can the axillary nerve injured?

Answer 39

Injured during dislocation >> close relation to inferior part of joint capsule

Question 40

How is an axillary nerve injury indicated?

Answer 40

1) Paralysis of deltoid muscle with loss of abduction 2) Loss of sensation in a small area of the skin "regimental badge area" over central part of deltoid supplied by the superior lateral cutaneous nerve