Known commonly as the armpit, a pyramid-shaped space between
the upper part of the arm and the side of the
chest. It forms an important passage for nerves, blood, and lymph vessels
as they travel from the root of the neck to the upper limb.
|Axilla with muscles and vessels exposed
The upper end of the axilla, or apex, is directed into
the root of the neck and is bounded in front by the clavicle,
behind by the upper border of the scapula,
and medially by the outer border of the first 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.
The walls of the axilla are made up as follows:
The axilla contains the principal vessels and nerves to the upper limb and
many lymph nodes.
- Anterior wall, by the pectoralis major, subclavius,
and pectoralis minor muscles,
the clavipectoral fascia, and the suspensory ligament of the axilla.
- Posterior wall, by the subscapularius, latissimus
dorsi, and teres major muscles from above down.
- Medial wall, by the upper four or five ribs and the
intercostal spaces covered by the serratus
- Lateral wall, by the coracobrachialis and biceps
muscles in the bicipital groove of the humerus,
- The base is formed by the skin stretching between
the anterior and posterior walls.