ABSTRACT
The axilla, or armpit, is a pyramid-shaped space between the upper part of the arm and the side of the chest. The upper end or apex is directed into the root of the neck. It is bounded in front by the clavicle, behind by the border of the scapula, and medially by the outer border of the 1st rib. The lower end, or base, is bounded in front by the anterior axillary fold (formed by the lower border of the pectoralis major muscle), behind by the posterior axillary fold (formed by the tendon of latissimus dorsi and the teres major muscle) and medially by the chest wall.
