Adrenal glandA small, flattened, yellowish gland on the upper end of each kidney. The right one is roughly triangular. The left is crescent-shaped.
KidneyThe kidney the gland sits on. Adrenal glands get their name from where they sit, by the kidneys.
Suprarenal veinDrains blood, carrying the gland's hormones, away from the gland. The right one runs into the inferior vena cava.
Suprarenal arteriesMany small arteries that bring blood to the gland. They come from the aorta, the inferior phrenic artery and the renal artery.
Inside the gland: 6 6
CapsuleThe thin covering round the outside of the gland.
Adrenal cortexThe outer part of the gland, making up most of it. It makes steroid hormones, including aldosterone and cortisol, in three zones.
Zona glomerulosaThe outermost zone of the cortex, just under the capsule. Its cells are in rounded groups. It makes aldosterone.
Zona fasciculataThe middle and thickest zone of the cortex, its cells in columns. It makes cortisol.
Zona reticularisThe innermost zone of the cortex, in contact with the medulla. Its cells are in an irregular network. It makes androgens.
Adrenal medullaThe soft inner core, full of blood spaces. Its chromaffin cells make adrenaline and noradrenaline.
How this list was compiled: Read 2026-09-27. (1) Gray's Anatomy of the Human Body, 20th edition (1918), The Suprarenal Glands and figure 1185, https://www.bartleby.com/107/277.html : two small flattened yellowish bodies above and in front of the upper end of each kidney, the right triangular and the left crescentic; the suprarenal vein emerging from the hilum, the right joining the inferior vena cava; arteries from the aorta, the inferior phrenic and the renal; on section an external cortical and an internal medullary portion; the zona glomerulosa beneath the capsule, the zona fasciculata of radial columns, and the zona reticularis in contact with the medulla; the vascular medulla of chromaphil cells concerned with the secretion of adrenalin. (2) Wikipedia, Adrenal gland, https://en.wikipedia.org/wiki/Adrenal_gland : the glands above the kidneys, the right pyramidal and the left crescent-shaped; a fatty capsule; the outer cortex producing steroid hormones in three zones, glomerulosa, fasciculata and reticularis (mineralocorticoids such as aldosterone, glucocorticoids such as cortisol, and androgens); the inner medulla's chromaffin cells producing adrenaline and noradrenaline; the suprarenal veins; up to 60 small arteries entering each gland. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
These are the parts of the adrenal (suprarenal) gland: first the right gland on top of its kidney, then a magnified slice from the capsule down to the medulla at the centre.
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Where it sits
Each adrenal gland caps the upper end of a kidney. Many small suprarenal arteries bring blood in, from the aorta, the inferior phrenic artery and the renal artery, and the suprarenal vein carries it away.
Its layers
Under the capsule is the cortex, in three zones: the zona glomerulosa, then the thick zona fasciculata of radial columns, then the zona reticularis next to the medulla. At the centre is the medulla, soft and full of blood spaces, which makes adrenaline.
The zones in order from the outside in: glomerulosa, fasciculata, reticularis. They make aldosterone, cortisol and androgens, in that order.
Questions and answers
What are the two main parts of the adrenal gland?
The cortex, the outer part that makes steroid hormones such as aldosterone and cortisol, and the medulla, the inner core that makes adrenaline and noradrenaline.
What are the three zones of the adrenal cortex?
From the outside in: the zona glomerulosa, the zona fasciculata and the zona reticularis.
Where are the adrenal glands?
On top of the kidneys, one on each. The right one is roughly triangular and the left one crescent-shaped.