Where are Adrenal Glands Located?Adrenal glands are orange-colored glands located on the top of both kidneys. Adrenal glands are about the size of a small lemon and are triangular shaped, sitting on top of the kidney like a hat. Everyone has two adrenal glands that make several important hormones that are required for healthy life. Although some adrenal conditions are treated with hormones, most adrenal diseases are treated with surgery to remove the adrenal gland or the adrenal tumor that is causing a very specific hormone problem. Adrenal.com has hundreds of pages of information about the adrenal gland organized in easy to navigate groups.
The Right Adrenal Gland. The adrenal gland on the right side is located on top of the right kidney and is very close to the inferior vena cava (IVC). This vein (IVC) is the biggest vein that brings back blood back to the heart from the entire body. The right adrenal gland is also very close to the liver and the right kidney. All these structures are incredibly important and it is absolutely crucial that the adrenal surgeon is experienced in dealing with these very important structures. If the surgeon is off by just millimeters the operation can very rapidly end up with tremendously bad outcomes.
The Left Adrenal Gland. The left adrenal gland is located on top of the left kidney. It is very close to the splenic artery which is the major artery that goes to the spleen, the spleen as well as the tail of the pancreas. The pancreas is a very sensitive organ that when irritated or inflamed can cause significant sickness and death. Thus, again it is exceedingly important that surgery in this area is performed very gently by exceedingly experienced surgeons. If the surgeon is off by just millimeters the operation can very rapidly end up with tremendously bad outcomes
FIGURE 1: A normal adrenal gland demonstrating the adrenal medulla (inner layer), and the adrenal cortex (outer layer). The adrenal glands are shaped like a flattened triangle. And they really are orange in color!
Difference Between Adrenal Medulla and Adrenal Cortex.The adrenal medulla and cortex have completely different functions and produce completely different hormones. In fact, when babies are only a few weeks old the adrenal glands become formed from two different cell types and two different areas of embryonic formation. Inside the Adrenal Gland: The Medula and Cortex. The adrenal glands are paired (you have two of them) flat glands with a triangular shape, each weighing about 5 grams (about half of a lime). When we cut the adrenal gland in half, we can see with our eyes two distinct regions which are different shades of orange. These two major sections of the adrenal are called the adrenal medulla (inner layer), and the adrenal cortex (outer layer).
The Adrenal Medulla. The adrenal medulla comes from the neural crest (i.e. embryological basis similar to your central and peripheral nervous systems). It contains homogeneous sheets of cells organized into nests. Cells have large varied nuclei and abundant cyto¬plasm packed with numerous secretory granules con-taining catecholamines (fight or flight hormones) and other substances specific to chromaffin cells.
The Adrenal Cortex. The adrenal cortex is of mesodermal origin and is derived from the adrenogenital ridge (sorry folks for the technical stuff). The adrenal cortex is organized into three layers, each with a different function.
- The most superficial layer is the zona glomerulosa, responsible for aldosterone production.
- The middle zone is the zona fasciculata containing radial columns of lipid-laden (fat-filled) cells that primarily produces cortisol.
- The inner layer, zona reticularis, store cholesterol for steroidogenesis (the making of steroids) and the secretion of sex hormones such as estrogen, and testosterone (in small amounts).
Blood Supply to the Adrenal Glands.The blood supply to the adrenal is threefold: via the superior adrenal arteries from the inferior phrenic arteries, the middle adrenal from the aorta, and the inferior adrenal artery from the renal arteries. Blood passes from the outer cortex to the inner medulla, and the gland is drained in most cases by a single central vein which empties its blood into the vena cava on the right and the renal vein on the left.
FIGURE 2: What normal adrenal glands (right next to the liver; left next to the spleen) look like on a CT scan.Adrenal surgery is discussed on other pages of this website, but now that you know about the anatomy of the adrenal gland you understand why adrenal surgery is tricky and should be done by an expert that does many adrenal operations every week. If your surgeon isn't performing adrenal surgery every week, then you may want to find a surgeon with much more expertise. Outcomes are directly related to the experience of the surgeon and how many adrenal operations he/she does every week. Our patients fly from all over the world to have surgery with us because of our very high volumes and excellent outcomes.