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Structure

Adrenal gland

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The adrenal (suprarenal) glands are paired retroperitoneal endocrine glands that sit above the kidneys. The cortex produces steroid hormones and the medulla secretes catecholamines.

Terminologia Anatomica (Latin): Glandula suprarenalis · Open in the 3D atlas

Location

Each gland lies at the upper pole of the kidney, at about T12, within the perirenal fat and renal fascia but separated from the kidney by a fibrous septum. The right gland is pyramidal and lies behind the inferior vena cava and liver; the left is crescentic and lies behind the stomach, pancreas and splenic vessels.

Structure

The cortex has three zones: zona glomerulosa (mineralocorticoids, aldosterone), zona fasciculata (glucocorticoids, cortisol) and zona reticularis (adrenal androgens), remembered as salt, sugar, sex from outside inward. The medulla is derived from neural crest and contains chromaffin cells secreting adrenaline (epinephrine) and noradrenaline.

Blood supply

Three groups of arteries supply each gland: superior suprarenal (from the inferior phrenic), middle suprarenal (from the aorta) and inferior suprarenal (from the renal artery). A single large suprarenal vein leaves each gland: the right drains short and directly into the inferior vena cava, the left joins the left inferior phrenic vein and enters the left renal vein.

Innervation

The medulla is directly innervated by preganglionic sympathetic fibres from the greater, lesser and least splanchnic nerves (T5-T12) that synapse on chromaffin cells, which act as modified postganglionic neurones. The cortex is regulated hormonally (ACTH, angiotensin II, potassium).

Function

Cortisol supports metabolism, stress response and immune modulation under hypothalamic-pituitary control (CRH, ACTH); aldosterone regulates sodium and potassium handling and volume under the renin-angiotensin system. The medulla releases catecholamines in the fight-or-flight response.

Clinical correlations

Principal conditions are Cushing syndrome (cortisol excess; exogenous steroids are the commonest cause), primary aldosteronism (Conn), Addison disease and adrenal insufficiency, congenital adrenal hyperplasia, phaeochromocytoma and incidentalomas. Abrupt cessation of long-term steroids risks adrenal crisis; management follows local guidelines.

Common exam points

  • Cortex zones (outside in): glomerulosa, fasciculata, reticularis; medulla = chromaffin cells.
  • Right suprarenal vein drains into the IVC; left into the left renal vein.
  • Arteries: superior (inferior phrenic), middle (aorta), inferior (renal).
  • Medulla receives preganglionic sympathetic fibres (T5-T12 splanchnic nerves).
  • Cortisol is regulated by ACTH; aldosterone mainly by renin-angiotensin and potassium.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Williams Textbook of Endocrinology. Elsevier, 14th edition (2019) — Tier 3 (textbook)

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