The Pectoral Region

Question 1

Pectoralis Major

Answer 1

O: Clavicular head (anterior surface of medial clavicle), Sternal head (anterior surface of the sternum, upper six costal cartilages and aponeurosis of external oblique muscle)

I: Intertubecrcular sulcus of humerus

I: Medial pectoral nerve (C8-T1)

A: Adduction, flexion and internal rotation of the arm

Question 2

Pectoralis Minor

Answer 2

O: 3rd-5th ribs

I: Coracoid process of the scapula

I: Medial pectoral nerve (C8-T1)

A: Stabilises scapula (draws anterioinferiorly against the thoracic wall)

Question 3

Serratus Anterior

Answer 3

O: Ribs 1-8 (separate slips)

I: Medial border of scapula

I: Long thoracic nerve

A: Protracts the scapula and abduction above 90 at shoulder (rotates medial border of the scapula anterioinferiorly)

Question 4

In conditions of high metabolic demand or in respiratory, what do muscles do to help?

Answer 4

Act as accessory muscles of respiration by elevating the ribs

Question 5

Coracobrachialis

Answer 5

O: Coracoid process of the scapula

I: Medial side of the humeral shaft

I: Musculocutaneous nerve

A: Flexion of the arm and weak abductor

Question 6

Subclavius

Answer 6

O: 1st rib

I: Inferior surface of the middle third of clavicle

I: Nerve to subclavius

A: anchors and depresses the clavicle

Question 7

Deltoid

Answer 7

O: Anterior border and upper surface of the lateral third of clavicle

I: Deltoid tuberosity of the humerus

I: Axillary nerve

A:

• Anterior = flexion and medial rotation of the arm
• Middle fibres = abduct the arm from 15-90°
• Posterior fibres = extend and laterally rotate the arm

Question 8

What is the axilla?

Answer 8

• Pyramidal space at the junction of upper limb and the thorax
• Provides a passageway for neurovascular structures

Question 9

What forms the lateral wall of the axilla?

Answer 9

Lateral wall = interburcular sulcus of the humerus

Question 10

What forms the medial wall of the axilla?

Answer 10

Medial wall = serratus anterior, ribs, intercostal muscles

Question 11

What forms the anterior wall of the axilla?

Answer 11

Anterior wall = pec major, pec minor and subclavius

Question 12

What forms the posterior wall of the axilla?

Answer 12

Posterior wall = subscapularis, teres major and latissimus dorsi

Question 13

What are the contents of the axilla?

Answer 13

• Axillary artery
• Axillary vein
• Cords of the brachial plexus
• intercostobrachial nerve
• axillary lymph nodes
• biceps brachii and coracobrachialis

Question 14

What are the three main routes by which structures leave the axilla?

Answer 14

• inferiorly and laterally
• quadrangular space (intermascular space where axillary nerve and posterior circumflex humeral artery pass)
• clavipectoral triangle (cephalic vein enters axilla through here, medial and lateral pectoral leaves)

Question 15

What are the borders of the clevipectoral triangle?

Answer 15

Pectorialis major
Clavicle
Deltoid

Question 16

What are the six groups of the axillary lymph nodes? (hint: APICAL)

Answer 16

Anterior
Posterior
Infraclavicular
Central
Apical
Lateral

Question 17

Where does the axillary artery come from?

Answer 17

Subclavian artery once it enters the axilla via lateral border of the first rib

Question 18

What is the axillary sheath?

Answer 18

a fibrous layer that envelops the axillary artery, axillary vein, the three cords and branches of the brachial plexus

Question 19

What are the three parts of the axillary artery?

Answer 19

(named relative to pectorial minor)

1) First part
- superior thoracic artery

2) Second part
- Thoracoacromial artery
- Lateral thoracic artery

3) Third part
- Subscapular artery
- Anterior circumflex humeral artery
- Posterior circumplex humeral artery

Question 20

Where is the axillary vein formed?

Answer 20

Lower border of the teres major

-ascends through axilla anteromedially

Question 21

What are the two major superficial veins of the upper limbs?

Answer 21

Cephalic and Basilic

Question 22

What is axillary lymphadenopathy?

Answer 22

Enlargement of the axillary lymph nodes

-from infections and neoplasia