The thymus gland is a small organ that is situated directly behind the sternum and in the front section of the chest. It is positioned between the lungs and a space in the chest called the mediastinum, which is where a number of lymph nodes, a section of the trachea, the esophagus, part of the aorta and the heart are also located.
The thymus is positioned above and in front of the heart, and it is split into two halves named lobes. It consists of a thin outer layer called the capsule, an inner layer named the medulla and a third layer called the cortex that surrounds the medulla and weighs around 1 ounce during puberty but shrinks during adulthood. The thymus gland is a crucial component that is responsible for maintaining proper immune system function in the body.