Chapter 70: Suprarenal Gland Anatomy

Suprarenal Gland Anatomy provides a comprehensive anatomical and clinical overview of the suprarenal (adrenal) glands, golden yellow organs situated immediately superior and slightly anterior to the kidneys and enclosed within the renal fascia. The glands are structurally differentiated, with the right gland typically pyramidal and possessing a three-pointed star cross-section, resting upon the superior pole of the kidney and lying posterior to the inferior vena cava and the right hepatic lobe. Conversely, the left gland is semi-lunar and is positioned near the left crus of the respiratory diaphragm, with its anterior surface related to the stomach, spleen, and pancreas. Functionally, the gland is divided into the outer cortex, derived from mesoderm and essential for life, and the inner medulla, derived from neural crest cells. The cortex is subdivided into three zones: the zona glomerulosa produces mineralocorticoids, such as aldosterone, vital for electrolyte and water balance; the zona fasciculata generates glucocorticoids, including cortisol, which supports carbohydrate balance; and the zona reticularis synthesizes sex hormones like dehydroepiandrosterone (DHEA). The medulla is composed of chromaffin cells that are analogous to postganglionic sympathetic neurons, storing and releasing catecholamines, specifically adrenaline and noradrenaline, primarily regulated by cholinergic preganglionic sympathetic fibers from the splanchnic nerves. The glands exhibit an exceptionally high arterial flow rate, supplied by superior, middle, and inferior suprarenal arteries, with some vessels bypassing the cortical sinusoids to supply the medulla directly. Venous drainage is via a central vein forming the suprarenal vein; the right suprarenal vein is short and drains directly into the inferior vena cava, making it particularly vulnerable during surgery, while the longer left vein typically drains into the left renal vein. The chapter also extensively covers relevant pathology, including functional adenomas that cause Conn’s syndrome (aldosterone excess) or Cushing’s syndrome (cortisol excess), requiring precise diagnosis via imaging or selective vein sampling and subsequent surgical excision. Other important lesions include catecholamine-producing phaeochromocytomas of the medulla, requiring pre-operative alpha-adrenergic blockade, benign myelolipomas, and aggressive adrenocortical carcinoma (ACC), which is typically large at presentation and requires en bloc surgical resection. Finally, the glands are common sites for metastases from other malignancies, and surgical removal (adrenalectomy) is frequently performed using minimally invasive techniques, often preferring the retroperitoneal approach to avoid the abdominal cavity.