Lecture notes on the axilla and the brachial plexus

Axilla
 Connects the neck to the upper limb.
 Channel through which the neurovascular supply of the
upper limb runs.
 Contains important lymph nodes that drain breasts.
 Axillary folds ----> 2 of them ----> formed by muscle covered
in skin ---> Posterior axillary fold and anterior axillary fold.
 Posterior ---> latissimus dorsi and teres major.
 Anterior ---> pectoralis major and minor.

Boundaries of the axilla
 A base, an apex and 4 walls (posterior, anterior, medial and
lateral). Midaxillary line
 Anterior ---> pectoralis major and minor.
 Medial ---> serratus anterior and thoracic wall.
 Posterior ---> subscapularis, teres major and latissimus
dorsi. Its anterior to the scapula.
 Lateral ----> Intertubercular sulcus.

Contents of the axilla
 Axillary artery + vein.
 Long thoracic nerve ----> serratus anterior muscle.
 Damage to thoracic nerve ---> winged scapula.
 Cords of brachial plexus.
 Short head of biceps brachii + coracobrachialis.

Blood supply of the axilla
 Comes from brachiocephalic trunk.
 Brachiocephalic trunk ------> subclavian artery ---> axillary artery (after 1 st rib + passes
behind middle 1/3rd of the clavicle).
 Axillary artery ----> brachial artery (pulse palpable).
 Important branch of axillary ----> circumflex humeral arteries + axillary nerve ---> runs
around the surgical neck of the humerus.
 Important branch of brachial ----> deep brachial artery (profunda brachialis) + radial
nerve ----> behind humerus in spiral groove ---> damaged during mid shaft fractures.
 Rich anastomoses at the back of scapula provide alternative route for blood to travel
from the subclavian artery to the brachial artery.

Lymph nodes in the axilla
 Drainage comes from
 Anterior thoracic wall
 Breast
 Posterior thoracic wall
 Upper limb