The Pectoral Region Flashcards
Pectoralis Major
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
Pectoralis Minor
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)
Serratus Anterior
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)
In conditions of high metabolic demand or in respiratory, what do muscles do to help?
Act as accessory muscles of respiration by elevating the ribs
Coracobrachialis
O: Coracoid process of the scapula
I: Medial side of the humeral shaft
I: Musculocutaneous nerve
A: Flexion of the arm and weak abductor
Subclavius
O: 1st rib
I: Inferior surface of the middle third of clavicle
I: Nerve to subclavius
A: anchors and depresses the clavicle
Deltoid
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
What is the axilla?
- Pyramidal space at the junction of upper limb and the thorax
- Provides a passageway for neurovascular structures
What forms the lateral wall of the axilla?
Lateral wall = interburcular sulcus of the humerus
What forms the medial wall of the axilla?
Medial wall = serratus anterior, ribs, intercostal muscles
What forms the anterior wall of the axilla?
Anterior wall = pec major, pec minor and subclavius
What forms the posterior wall of the axilla?
Posterior wall = subscapularis, teres major and latissimus dorsi
What are the contents of the axilla?
- Axillary artery
- Axillary vein
- Cords of the brachial plexus
- intercostobrachial nerve
- axillary lymph nodes
- biceps brachii and coracobrachialis
What are the three main routes by which structures leave the axilla?
- 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)
What are the borders of the clevipectoral triangle?
Pectorialis major
Clavicle
Deltoid
What are the six groups of the axillary lymph nodes? (hint: APICAL)
Anterior Posterior Infraclavicular Central Apical Lateral
Where does the axillary artery come from?
Subclavian artery once it enters the axilla via lateral border of the first rib
What is the axillary sheath?
a fibrous layer that envelops the axillary artery, axillary vein, the three cords and branches of the brachial plexus
What are the three parts of the axillary artery?
(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
Where is the axillary vein formed?
Lower border of the teres major
-ascends through axilla anteromedially
What are the two major superficial veins of the upper limbs?
Cephalic and Basilic
What is axillary lymphadenopathy?
Enlargement of the axillary lymph nodes
-from infections and neoplasia
