The endocrine function of the suprarenal glands makes their abundant blood supply necessary. The suprarenal arteries branch freely before entering each gland so that 50–60 branches penetrate the capsule covering the entire surface of the glands. Suprarenal arteries arise from three sources:
• Superior suprarenal arteries from the inferior phrenic arteries
• Middle suprarenal arteries from the abdominal aorta near the level of origin of the superior mesenteric aorta
• Inferior suprarenal arteries from the renal arteries