Pectoral Girdle, Shoulder, Arm & Elbow

Question 1

What are the 2 main palpable bony features on the anterior clavicle?

Answer 1

1. Acromion: palpable bony shelf above shoulder
2. Coracoid process: palpable below the lateral clavicle - shoulder joint space can accessed with a needle via a point 2cm inferior to this directly supero-laterally

Question 2

What is the attachment point for rotator cuff muscles?

Answer 2

Lesser tubercle of humerus

Question 3

What runs through the intertubercular (bicipital) groove?

Answer 3

Tendon of the long head of the biceps muscle

Question 4

What are the surface anatomy landmarks of the superior and inferior angles of the scapula inferiorly?

Answer 4

T2-T7 spinous processes with the medial spine sitting at T3 spinous process

Question 5

The medial scapula border of an abducted upper limb posteriorly marks the _________.

Answer 5

Oblique lung fissure

Question 6

What is the function of the clavicle? When is it at risk of fracture?

Answer 6

Acts a strut supporting the upper limb and transmitting forces to axial skeleton - risk of fracture when a patient falls onto outstretched limb or onto lateral shoulder

Question 7

What are the joints of the shoulder?

Answer 7

1. Acromioclavicular: synovial plane joint passing anterior-posterior - dislocation (shoulder separation possible) and a visible deformity shows
2. Sternoclavicular: ONLY bone-bone joint between upper limb and axial skeleton functioning as a synovial B&S joint - dislocation rare due to good joint support
3. Glenohumeral (shoulder): lax B&S joint allowing wide range of movement (high risk of dislocation) made up of 3x glenohumoral ligaments that pass from margin of glenoid fossa of scapula to humeral head and support shoulder anteriorly

Question 8

Why must joint injection/aspiration of the sternoclavicular joint take place under ultrasound guidance?

Answer 8

Because the apex of the lungs sits here putting the patient at high risk of pneumothorax and also, the jugular and brachiocephalic veins sit here so its important to see what you are doing

Question 9

What supports the acromioclavicular joint?

Answer 9

1. Coracoclavicular ligaments: made up of trapezoid (posterior) and conoid (anterior) ligaments but can be torn by AC joint dislocation (once a patient does it 1x, there likely to do it again)
2. Coracoacromial ligament: supports shoulder joint superiorly so it cannot dislocate this way but can be ruptured by superiorly directed forces and can impinge on supraspinatus/subacromial bursa

Question 10

What will joints made of hyaline look like on an X-ray?

Answer 10

Like space as hyaline is less dense

Question 11

In order or frequency, where do fractures of the clavicle take place?

Answer 11

Weakest point of clavicle is the junction between the middle and lateral 1/3 > Middle 1/3 > lateral 1/3 > medial 1/3

Question 12

What will a fractured clavicle look like?

Answer 12

The separated parts of a fractured clavicle move in opposite direction due to muscle contraction of SCM and gravity so there will be a big step between the shoulder and neck

Question 13

What nerve is at risk of damage from a fracture of the surgical neck of the humerus? What symptoms would the patient have? Have examination findings would be present?

Answer 13

Axillary nerve - paraesthesia/LOS of skin over lower deltoid of upper lateral arm (regimental badge area) and weakness/paralysis of teres minor and deltoid muscles so the patient will not be able to abduct the affected limb and over long-term, the muscles of deltoid will atrophy giving the shoulder a flattened appearance

Question 14

What structures can be damaged by a mid-shaft humeral fracture through the spiral groove posteriorly?

Answer 14

Radial n.

Profunda brachii artery

Question 15

Why is the lower part of the shoulder joint capsule lax and folded?

Answer 15

To permit free movement especially ABDUCTION of the arm - this is why downward force applied to an abducted arm can dislocate the shoulder (can damage axillary n. too)

Question 16

What is the glenoid labrum? What happens if its damaged?

Answer 16

A fibrocartilage rim deepening the glenoid fossa shallow socket and stabilising the shoulder joint - tear can result from trauma/overuse and can produce a snapping sensation or pain on abduction or lateral rotation

Question 17

What is the bursa called in the shoulder? How can it become irritated? How can you inject it?

Answer 17

Subacromial bursa can become irritated and inflamed if a tendon of one of the rotator cuff muscles rubs on the acronium sat above due to wear or impingement - injection takes place via the acromio-deltoid groove

Question 18

What are the superficial muscles of the pectoral girdle, their function and innervation?

Answer 18

1. Trapezius: elevates, retracts and depresses the scapula (CNXI)
2. Latissimus dorsi: extends, adducts and medially rotates humerus and raises the trunk to arm e.g. climbing (thoracodorsal n.)

Question 19

What are the deeper muscles of the pectoral girdle, their function and innervation?

Answer 19

1. Levator scapulae: elevates and rotates scapula (dorsal scapula n. C3-4)
2. Rhomboid major and minor: retract and fix position of scapula (dorsal scapula n.)
3. Teres major: adduction and medial rotation of humerus (lower subscapsular n.)

Question 20

What are the borders of auscultation? Why it used?

Answer 20

1. Trapezius (runs from base of skull to T12 vertebrae with fibres running to acromium of scapula)
2. Rhomboid major
3. Latissimus dorsi

The skin here is thin so you can hear breath sounds very clearly in this area from the lower lobe

Question 21

What are the pectoralis muscles of the pectoral girdle, attachment points, their function and innervation?

Answer 21

1. Pectoralis major: attaches to clavicle, sternum and adjacent costal cartilages and lateral side of intertubercular groove of humerus - adducts and medially rotates the shoulder acting as an accessory breathing muscle (medial and lateral pectoral n.)
2. Pectoralis minor: attaches to ribs 3-5 and coracoid process - depresses and protracts the scapula dividing axillary artery into 3 parts (medial pectoral n.)

Question 22

What is the attachment points of the deltoid pectoral girdle muscles and their action? What is their innervation?

Answer 22

Attaches to lateral clavicle, acromion, scapula spine and humerus - brings about all shoulder movements EXCEPT adduction (axillary n.)

Question 23

Where is the axillary nerve? How can it become damaged? What would be the consequence of damage?

Answer 23

Passes around surgical neck of humerus ~ 5cm below acromion with circumflex humoral vessels so it can be damaged by shoulder dislocation, surgical neck of humerus # or IM injection (e.g. vaccines) and this would cause:

• Paralysis and wasting of deltoid and teres minor so patient would not be able to move shoulder much
• Limb hangs limb by side
• Loss of shoulder contour
• LOS over lateral shoulder (regimental badge region)

Question 24

What does a shoulder dislocation most often look like?

Answer 24

Anteriorly (but can also get posterior or inferior but NOT superior) where the humeral head comes out of glenoid fossa/infraglenoid tubercle anteriorly causing a loss of contour

Question 25

What are the 4 rotator cuff muscles, their function and innervation?

Answer 25

Rotator cuff muscles move and stabilise the shoulder joining it at the GT EXCEPT subscapularis which attaches to LT (where they can be ruptured/avulsed):

1. Supraspinatus: assists with initial part of arm abduction to 20 degrees (supracapsular n.)
2. Infraspinatus: lateral shoulder rotation (supracapsular n.)
3. Teres minor: lateral shoulder rotation (axillary n.)
4. Subscapularis: medial shoulder rotation (upper and lower subcapsular n.)

Question 26

How can the supracapsular nerve become impinged? What will this cause?

Answer 26

Under coracoacromial arch made up of the coracoacromial ligaments resulting in a painful arc of 50-130 degree abduction and the pain can radiate towards the hand

Question 27

What is the function of the serratus anterior pectoral girdle muddle? What is its innervation?

Answer 27

Attaches to ribs 1-8 and medial scapula border and protracts the scapula allowing you to reach out and holds it close to the thoracic wall without letting the scapula wing - innervated by long thoracic n. (at risk in axillary or breast surgery with node clearance)

Question 28

What is the axilla and its borders?

Answer 28

A fat-filled region located superior to the armpit skin containing important neurovasculature supplying the upper limb such as axillary artery, distal parts of brachial plexus and lymph nodes (coracobrachialis muscle is a useful landmark plane) bordered by:

1. Ant: anterior axillary fold and pectoral muscles
2. Post: posterior axillary fold, subscapularis and scapula
3. Med: serratus anterior and lateral thoracic wall
4. Lat: intertubercular groove

Question 29

What forms the 2 axillary folds? What can they be used for?

Answer 29

Posterior: latissimus dorsi and teres major -> track down for posterior axillary line

Anterior: pectoralis major and minor -> track down for anterior axillary line

Can be used to delineate safe region for chest tube insertion

Question 30

What is the axillary lymph node route?

Answer 30

Humeral (upper limb), subcapsular and pectoral nodes track to the central node, then the apical node and lastly the supraclavicular

Question 31

What regions drain lymph to the axillary nodes and therefore, what cancers can metastasize to here?

Answer 31

Upper limb
Breast (deep axillary tail of breast passes along anterior axillary fold)
Thin walls of chest
Abdomen above the navel

Question 32

What are the 2 compartments of the arm, their function and innervation?

Answer 32

1. Anterior: biceps brachii (long and short head), coracobrachialis and brachialis - flexors of shoulder/elbow and supinator of forearm (musculocutaneous n. + some radial n. to brachialis muscle) - tendons can be tapped to test C5-6 reflex
2. Posterior: triceps brachii (long, lateral and medial head) - extensors of shoulder/elbow (radial n.) - tendons can be tapped to test C7-8 reflex

Question 33

What are the functions of the muscles of the anterior arm compartment?

Answer 33

1. Biceps brachii: long head from supraglenoid tubercle where tendon passes through intertubercular groove and short head from coracoid process - flex shoulder/elbow and supinate forearm
2. Coracobrachialis: adducts arm
3. Brachialis: flexes elbow

Question 34

Where do the anterior arm muscle tendons attach to? Why is this relevant?

Answer 34

Radial tuberosity where they can avulse from it (median n. and brachial a. sit medially)

Question 35

What is the bicipital aponeurosis?

Answer 35

A superficial sheath that passes infero-medially and joins biceps with deep forearm fascia covering and protecting the medial n. and brachial a.

Question 36

What is the popeye sign?

Answer 36

When the tendon of the long head of the biceps brachii has avulsed from the radial tuberosity causing a contracted rounded prominence that looks like popeye’s arm (could be due to weakness of bone and soft tissue due to steroids or age)

Question 37

What are the key structures that the profundal artery and radial nerve travel through?

Answer 37

Triangular interval (space) and spiral groove

Question 38

What key space do the axillary nerve and posterior circumflex arteries travel through?

Answer 38

Quadrangular space

Question 39

What is the main motor and sensory supply to the upper limb?

Answer 39

Brachial plexus that emerges between the 2 scalene muscles (where parts can get trapped) and passes from neck down clavicle, through axilla and into upper limb - upper parts can be palpated, imaged and anaesthetized

Question 40

What is thoracic outlet syndrome?

Answer 40

Where a cervical rib traps a part of the brachial plexus causing paraesthesia and pain radiating down upper limb tracking the affected nerve

Question 41

What is the route of the brachial plexus?

Answer 41

1. Ventral rami of C5-T1 join and exchange neurons
2. Sits in posterior triangle of neck on way to axilla
3. Related to apex of lung, 1st rib and axillary artery
4. More distal parts run with axillary artery

SO vulnerable to stab, tumour or upper limb traction injuries

Question 42

What is the superficial venous drainage of the upper limb?

Answer 42

Cephalic

Basilic

Question 43

Where are infraclavicular lymph nodes? What is their clinical relevance?

Answer 43

Located in deltopectoral triangle/infraclavicular fossa and breast cancer can metastasize here

Question 44

What is the large deep venous drainage of the upper limb?

Answer 44

Follow the main axillary and subclavian arteries:

1. Basilic vein: travels deep to join brachial veins
2. Axillary vein: sits anterior to axillary a. and joined by cephalic vein
3. Subclavian vein: continuation of axillary vein from 1st rib medially (accessed below clavicle for central line)

Question 45

What is the blood supply to the upper limb?

Answer 45

1. Subclavian artery: passes between middle 1/3 of clavicle
2. Becomes axillary artery after crossing rib 1
3. Circumflex humeral arteries branch of at head/neck of humerus and run with axillary n.
4. Axillary artery becomes brachial artery below the teres major which passes down medial arm (pulse palpable here and medial to biceps tendon where it can be catheterized) with median and ulnar n.’s
5. Profunda brachii artery branches off and passes along spiral groove within posterior compartment (damaged by mid-shaft humeral fractures)

Question 46

What makes up the rich arterial anastomoses of the scapula? Why is this important?

Answer 46

Subclavian and axillary arteries - this can be exploited surgically as parts of the axillary artery can be clamped/removed w/o affecting limb perfusion