Axilla

Question 1

Give borders of the axilla

Answer 1

Boundaries/borders form a pyramid shape
Medially - serratus anterior, thoracic wall (ribs and intercostal muscles)
Laterally - intertubercular sulcus of the humerus
Anteriorly - pectoralis major, underlying pectoralis minor and subclavius
Posteriorly - subscapularis, latissimus dorsi, teres major muscles

Apex (axillary inlet), it is formed by lateral border of the first rib, superior border of scapula, and the posterior border of the clavicle.

Question 2

Give contents of axilla

Answer 2

○ neurovasculature bundle:
§ Axillary artery (w/ branches) - main artery supplying upper limb, split into three parts; only medial and posterior part travel w/in axillary
□ Medial part - medial to pectoralis minor
□ Lateral part - lateral to pectoralis minor
□ Posterior part - posterior to pectoralis minor
§ Axillary vein (w/ tributaries) - main vein draining upper limb
□ Two largest tributaries are cephalic and basilic veins
§ Brachial plexus (w/branches) - collection of spinal nerves that form peripheral nerves of the upper limb

○ Musculature:
§ Biceps brachii (short head) and coracobrachialis - travel through axilla attaching to coracoid process of scapula

○ Axillary lymph nodes - filter lymphatic fluid that has drained from the upper limb and pectoral region
§ Axillary lymph node enlargement is a non-specific indicator of breast cancer

Question 3

Describe the function of the axilla

Answer 3

Axilla (armpit) - a area inferior to the glenohumeral joint, at the junction of the upper limb and thorax; a passageway for neurovascular and muscular structures to enter/leave the upper limb

Size and shape of axilla varies with arm abduction - decreases in size during full arm abduction, leaving contents at risk of compression

Question 4

What is the floor of the axilla

Answer 4

axillary fascia and its skin on the surface of the axilla, aka the ‘armpit’

Question 5

What are the exiting passageways of the axilla

Answer 5

3 exiting passageways:
○ Main route of exit - immediately inferolaterally, into upper limb; majority of contents leave this exit
○ Quadrangular space - gap in posterior wall of axilla, allowing access to the posterior arm and shoulder region; axillary nerve and posterior circumflex humeral artery (branch of axilla artery) leave through this exit
○ Clavipectoral triangle - opening in anterior wall of axilla and bounded by pectoralis major, deltoid and clavicle; cephalic vein enters, medial and lateral pectoral nerves leave