The armpit, also known as the axilla, is the hollow area on the underside of the arm, where the arm and the shoulder join the torso. Numerous structure in the axillas, including blood vessels, nerves, tendons and lymph nodes, can cause armpit pain or discomfort. Armpit pain may be caused by traumatic injuries, overuse injuries or certain medical conditions.
Lymphadenitis
The lymph nodes are small structures located throughout the body -- including the armpit area -- that filter lymph fluid, which contains white blood cells that help ward off infection. Lymphadenitis, an infection of the lymph nodes or lymph glands, manifests when the lymph nodes become inflamed, often due bacterial, viral or fungal infection. Common signs and symptoms associated with lymphadenitis include swollen, tender and hard lymph nodes and red, tender skin overlying the involved lymph nodes. If an abscess -- a collection of pus in a tissue cavity -- has formed, lymph nodes may feel rubbery. Treatment options for lymphadenitis include antibiotics for the underlying infection, medication to control pain and anti-inflammatory medication.
Peripheral Artery Disease
Peripheral artery disease manifests when plaque -- a combination of fat, cholesterol, calcium and fibrous tissue -- accumulates in the arteries that transport blood to organs and tissues throughout the body. Plaque accumulation in the arteries is called atherosclerosis. Over time, plaque can cause hardening of the arteries, which can limit the amount of oxygenated blood that flows to the organs and extremities. Peripheral artery disease most commonly affects the legs, although it can affect the arteries traveling to the head, arms and organs such as the kidneys and the stomach. Certain risk factors can increase the likelihood of peripheral artery disease, such as smoking, age and certain medical conditions. Common signs and symptoms associated with upper extremity peripheral artery disease include pain, discomfort, tiredness, heaviness or cramping in the affected armpit and arm, muscle atrophy or wasting, decreased pulse strength, an inability to tolerate cold and skin discoloration.
Subscapularis Muscle Strain
Subscapularis muscle strains are a common injury among athletes, especially those who participate in throwing activities such as javelin throwing and pitching, according to the Sports Injury Clinic website. The subscapularis muscle is a large triangular muscle that sits on the front side of the shoulder blade. The tendon of the subscapularis muscle inserts into the arm bone in the armpit. The function of the subscapularis muscle is to stabilize the shoulder and rotate the arm inward. A partial muscle tear or strain is more common than a complete tear or rupture. Common symptoms associated with a subscapularis muscle strain include pain when the affected shoulder is moved, pain when the arm is rotated inward against resistance and pain in the armpit when the muscle's tendinous insertion -- the location where the tendon attaches to the humerus bone -- is pressed. Treatment options for subscapularis muscle strains include rest, heat and certain physical therapy modalities.
