Suprarenal Arteries

The suprarenal arteries are the vessels that supply arterial blood to the adrenal (suprarenal) glands. Each adrenal gland receives blood from three primary arterial sources, forming a rich anastomotic network that supports the high metabolic and hormonal demands of both the adrenal cortex and medulla. Despite the small size of the adrenal glands, their arterial supply is disproportionately extensive, reflecting their endocrine function and importance in systemic physiology.

Origin of Suprarenal Arteries

There are three main suprarenal arteries on each side, named according to their anatomical origin:

Each of these arteries gives rise to numerous small branches (up to 50) that form a subcapsular plexus before penetrating the gland.

Course and Distribution

• Upon reaching the gland, the arteries divide into fine arterioles that anastomose beneath the capsule of the adrenal gland
• From this subcapsular plexus, cortical sinusoids are formed that supply the zona glomerulosa, fasciculata, and reticularis
• Blood then flows inward toward the medulla in a centripetal direction
• Medullary arterioles may also originate directly from the suprarenal arteries and penetrate deep into the medulla, bypassing the cortex (dual supply)

Functional Significance

The adrenal gland has a unique vascular structure that supports hormone synthesis and systemic release:

• Dual vascular supply to the medulla (direct and cortical-derived) facilitates interaction between cortical and medullary products
• Cortisol-rich blood from the cortex enhances phenylethanolamine-N-methyltransferase (PNMT) activity in chromaffin cells, converting norepinephrine to epinephrine
• High blood flow (~5–6 mL/min/g of tissue) ensures rapid hormone secretion into systemic circulation

Venous Drainage (Brief Context)

• All blood from the suprarenal arteries eventually drains into the central suprarenal vein
• Right suprarenal vein: Drains directly into the inferior vena cava
• Left suprarenal vein: Drains into the left renal vein

Clinical Relevance

Adrenal Surgery

• Understanding arterial anatomy is critical during adrenalectomy to prevent ischemia or hemorrhage
• Accessory or aberrant suprarenal arteries are common and must be identified intraoperatively

Adrenal Hemorrhage

• Newborns, trauma patients, and those with sepsis may develop adrenal hemorrhage due to rupture of the fragile suprarenal vessels
• Hemorrhage can be unilateral or bilateral and may result in adrenal insufficiency

Imaging

• Suprarenal arteries are usually not visualized on standard imaging but can be seen in angiography
• Preoperative planning for adrenal tumor resection may involve CT angiography to evaluate vascular supply

Renal Transplantation Context

• Inferior suprarenal arteries may be encountered during dissection of renal vessels and should be preserved or ligated carefully

Variations

• The number and size of suprarenal arteries vary significantly between individuals
• Superior suprarenal arteries are usually the most numerous; the middle artery is often singular
• Accessory suprarenal arteries may arise from the aorta, intercostal arteries, or gonadal arteries