Armpit Armpit Armpit, or axilla, is the hollow place under the arm at the shoulder. Strong muscles attached to the chest and shoulder blade form the front and back walls and help to move the arm. The armpit contains arteries and veins, a network of nerves for the arm, sweat glands, lymph glands, and, in adults, hair. Armpit abscesses may be caused by heavy sweating, infrequent washing, obstructed sweat glands, or too frequent shaving of the hair.
Abscesses appear more often in people who have diabetes.
Pain in the armpit may be caused by boils, allergic skin problems, or swollen lymph glands. Painless swelling in the armpit may be a symptom of Hodgkin's disease.