axillen

Axillen, in English often referred to as the axillae or armpits, are the pyramidal spaces located beneath the shoulder joint between the upper arm and the chest wall. They function as passageways for nerves and vessels traveling to the upper limb and as a major lymphatic drainage center.

The boundaries of each axilla include a base formed by the skin and fascia, an apex bordered by the clavicle, first rib, and superior border of the scapula, an anterior wall mainly formed by the pectoralis major and minor, a posterior wall formed by the subscapularis, teres major, and latissimus dorsi, and a medial wall comprising the upper thoracic wall and serratus anterior. The contents comprise fat and connective tissue, the axillary artery and vein with their branches, the brachial plexus cords and branches, and a complex set of axillary lymph nodes.

Vascular and nervous structures pass through the axilla. The axillary artery is a continuation of the subclavian artery and has three parts with branches including the superior thoracic, thoracoacromial trunk, lateral thoracic, subscapular, and circumflex humeral vessels. The axillary vein accompanies the artery and drains into the subclavian vein. The brachial plexus traverses the axilla, giving rise to nerves such as the median, ulnar, radial, musculocutaneous, axillary, and radial nerves, as well as several cutaneous branches.

The lymphatic system in the axilla contains several groups of lymph nodes (pectoral, subscapular, lateral, central, and apical) that drain the upper limb, chest wall, and breast. Clinically, axillary lymphadenopathy can indicate infection, inflammatory disease, or metastatic spread from breast cancer, making sentinel lymph node biopsy and careful assessment important in certain conditions.