The thymus is a small organ in the chest with an integral role in body functioning. Within the thymus, special cells mature and help control and shape the immune response. Because of its importance to the immune system and endocrine system, the thymus can also be the source of several dangerous conditions.


1. Location

The thymus gland sits beneath the sternum in the upper-middle section of the chest, stretching up towards the neck. The two lobes that make up the thymus can stretch from below the thyroid in the neck to as low as the fourth rib. The thymus rests on the pericardium, the membrane that surrounds the heart.

3d thymus graphic janulla / Getty Images


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