where is thymus gland located in the body
Thymus The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, T cells mature. T cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders. The thymus is composed of two identical lobes and is located anatomically in the anterior superior mediastinum, in front of the heart and behind the sternum. Histologically, each lobe of the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule. The cortex and medulla play different roles in the development of T cells. Cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin (derived from bone marrow resident hematopoietic stem cells). Developing T cells are referred to as thymocytes and are of hematopoietic origin. Stromal cells include epithelial cells of the thymic cortex and medulla, and dendritic cells.
Thymus In children, the thymus is pinkish-gray, soft, and lobulated on its surfaces. At birth it is about 4–6 cm long, 2.5–5 cm wide, and about 1 cm thick.[1] It is made up of two lobes that meet in upper midline, that stretch from below the thyroid in the neck to as low as the cartilage of the fourth rib.[1] It lies beneath the sternum, rests on the pericardium, and is separated from the aortic arch and great vessels by a layer of fascia. The left brachiocephalic vein may even be embedded within the thymus.[1] In the neck, it lies on the front and sides of the trachea, behind the sternohyoidei and sternothyreoidei.[1]
Small intestine Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:
Small intestine Food from the stomach is allowed into the duodenum through the pylorus by a muscle called the pyloric sphincter.