Background: Function of the adrenal glands
Where are the adrenal glands?
The adrenal glands are small glands that sit on top of the kidneys in the retroperitoneum (i.e. the deepest part of the abdomen). They are several centimeters in length and each weighs 4-6 grams. The right gland looks like a small pyramid and sits next to the inferior vena cava (the large vein that carries blood from the legs and abdomen back to the heart), liver, and kidney. The right adrenal gland typically has one adrenal vein that empties directly into the inferior vena cava. Occasionally, a person may have two smaller right adrenal veins. The left adrenal gland is shaped more like a crescent and sits next to the aorta (the large artery that takes blood from the heart to the rest of the body), colon, stomach, and spleen. The left adrenal gland has a single adrenal vein that empties into the renal vein (the vein from the kidney). The right and left adrenal glands receive their blood supply from multiple blood vessels coming from the aorta, the diaphragm, and the kidney vessels.
The adrenal glands have two layers: the cortex and the medulla. The adrenal gland is like a peanut butter sandwich where the peanut butter is the medulla and the cortex is the bread. Each layer in this sandwich makes different hormones.