Adrenal Gland Embryology, Anatomy, and Physiology

Surgeons who treat patients with adrenal gland disorders need to understand basic adrenal gland embryology, physiology, and anatomy. The adrenal gland is made up of two parts—the cortex and the medulla—that have different embryologic origins and functions. The outer cortex produces steroid hormones and the inner medulla arises from the neural crest and produces catecholamines. The unregulated secretion of steroids or catecholamines results in the specific clinical manifestations of medullary and cortical tumors. The adrenal glands are paired retroperitoneal structures above the kidney with variable blood supply and knowing their relationship to the aorta, inferior vena cava, and other retroperitoneal structures is critical to understanding the conduct of adrenal operations. Surgical intervention may be required for definitive treatment of adrenal gland disorders; therefore, every surgeon involved in treating children with adrenal pathology needs a thorough understanding of adrenal gland embryology, physiology, and anatomy. This chapter reviews these topics with special emphasis on how they relate to diseases of the adrenal gland and especially their surgical treatment. Adrenal gland embryology is reviewed first as it explains many unique aspects of adrenal anatomy, histology, and physiology. Adrenal physiology is then reviewed as it forms the basis to understand problems of deranged adrenal function, especially the unregulated secretion of steroids or catecholamines that are common manifestations of adrenal tumors. Finally, the anatomy of the adrenal glands and surrounding structures is considered as this explains the clinical findings of mass effects on adjacent organs of functional and nonfunctional adrenal tumors and, most importantly, forms the basis to understand the conduct of adrenal operations.