Lymph nodes produce immune cells to help fight infection. They also filter the lymph fluid and remove foreign material, such as bacteria and cancer cells. They can become swollen from inflammatory conditions, an abscess, cancer, and most commonly from infection. Common areas where lymph nodes can be felt include the groin, armpit, behind the ears, back of the head, sides of the neck and under the jaw and chin.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, and Stephanie Slon.