Armpit

The armpit, or axilla, is a small, pyramidal hollow located beneath the shoulder joint where the upper arm meets the torso. Each person has two axillae. The area is bordered by the chest wall and the upper arm and contains skin folds that can collect moisture.

Anatomically, the axilla contains key vessels and nerves, including the axillary artery and vein and portions of the brachial plexus. It also houses axillary lymph nodes that drain lymph from the upper limb and chest wall. The space includes fat, connective tissue, hair follicles, and two types of sweat glands: eccrine glands for temperature regulation and apocrine glands concentrated in the armpit.

Functions include thermoregulation through sweating, and, in some individuals, odor production from apocrine secretions in combination with skin bacteria. The axillary lymph nodes play a role in immune surveillance by filtering lymph drained from the arm and chest wall.

Variations are common in hair distribution, skin tone, and odor, influenced by hormones and microbiota. The armpit is susceptible to irritation from shaving, friction, or certain deodorants. Common conditions include dermatitis, fungal infections, and hidradenitis suppurativa. Swollen lymph nodes may indicate infection or, less often, other medical conditions; persistent or painless swelling warrants medical evaluation.

Care and hygiene typically involve regular gentle washing with soap, keeping the area dry, and using deodorants or antiperspirants if desired. If irritation or a rash occurs, reducing irritants or switching products can help. Seek medical advice for persistent symptoms, severe pain, fever, or rapidly enlarging lumps.