Anatomy of Adrenal Gland

Dr.P.Viswakumar. M.SAssistant professor,

Dept.of General surgery

Embryology

• The adrenal glands form from two separate primordia: the neuroectodermal component develops into the adrenal medulla.

• The mesodermal component becomes the adrenal cortex.

• The cells of Future medulla travel along the nerves of the 6th to 12th segments into the developing cortical primordia.

• Within the cortical tissue, the migrating cells proliferate and differentiate into chromaffin cells at around the third month of gestation.

• The mesodermal component of the cortex is visible as early as the fourth week.

• Differentiation of cortical zones begins in the eighth week.

• These zones may be distinguished at birth although they do not appear in the final adult form until the fourth year of postnatal life

Accessory Adrenal Tissue

Surgical Anatomy

• The adult adrenal gland weighs 4 to 8 g and measures 4 x 3 x 1 cm.

• It is larger in women than in men.• The adrenal glands are composed of two

distinct parts, with differing functions and embryonic origins.

• The volume of the larger portion, the cortex, is 8 to 20 times that of the medulla.

Surgical Anatomy

• The adrenal glands lie on the anteromedial surface of the kidneys near the superior poles; both the glands and the kidneys are retroperitoneal.

• The two glands differ in shape. • The left is more flattened and has more

extensive contact with the kidney. • It is crescentic or semilunar in form, and may

extend on the medial surface of the kidney almost to the hilum

Surgical Anatomy

• The right gland is more triangular or pyramidal and lies higher on the kidney.

• Each adrenal gland, together with the associated kidney, is enclosed in the renal fascia (of Gerota)

• It is surrounded by fat, although the adrenal gland is separated from the kidney by a partition of connective tissue.

• The perirenal fat is more yellow and of a firmer consistency than fat elsewhere in the abdomen.

Surgical Anatomy

• The adrenal glands are firmly attached to the fascia, which is in turn firmly attached to the abdominal wall and to the diaphragm.

• The inferior phrenic arteries pass superior to the adrenals to reach the diaphragm.

• The inferior phrenic arteries give off a series of branches, the superior adrenal arteries, like teeth of a comb.

• A layer of loose connective tissue separates the capsule of the adrenal gland from that of the kidney

Surgical Anatomy-Relations

• Right adrenal :Anterior

Superior: "bare area" of the liver.Medial: inferior vena cavaLateral: "bare area" of the right lobe

of the liver.Inferior: peritoneum and first part of the duodenum.

• Posterior surface:Superior: Diaphragm.Inferior : Anteromedial aspect of the

right kidney.

LEFT ADRENAL GLAND :• Anterior surface :

Superior: peritoneum (posterior wall of the omental bursa) and the stomach.Inferior : Body of the pancreas

• Posterior surface:Medial: left crus of the diaphragmLateral: medial aspect of the left kidney

Vascular Supply

Arterial Supply : • The adrenal glands and the thyroid gland are the

viscera having the greatest blood supply per gram of tissue.

• As many as 60 arterial twigs may enter the adrenal gland.

• The arterial supply of the adrenal glands arises, in most cases, from three sources 1)Superior adrenal arteries 2)Middle adrenal artery 3) Inferior Adrenal artery

• All these arteries branch freely before entering the adrenal gland, so 50-60 arteries penetrate the capsule over the entire surface.

Venous Drainage

• The adrenal venous drainage does not accompany the arterial supply, and is much simpler.

• A single vein drains the adrenal gland, emerging at the hilum.

• The left vein passes downward over the anterior surface of the gland. This vein is joined by the left inferior phrenic vein before entering the left renal vein.

Venous Drainage

• The right vein is typically very short; it may be 0.5 cm long, or even less.

• The right adrenal vein passes obliquely to open into the posterior side of the inferior vena cava.

• The right adrenal vein does not usually have any tributaries other than from the adrenal gland.

• The right adrenal vein may drain into the right hepatic vein, close to the junction of the hepatic vein with the inferior vena cava.

Lymphatic Drainage

• The lymphatics of the adrenal gland are usually said to consist of a profuse subcapsular plexus that drains with the arteries and a medullary plexus that drains with the adrenal veins.

• Drainage is to renal hilar nodes, lateral aortic nodes, and to nodes of the posterior mediastinum above the diaphragm by way of the diaphragmatic orifices for the splanchnic nerves.

• The majority of capsular lymphatic vessels pass directly to the thoracic duct without the intervention of lymph nodes.

Innervation• The adrenal cortex appears to have only

vasomotor innervation. • Most of the fibers reaching the gland from the

splanchnic nerves, the lumbar sympathetic chain, the celiac ganglion, and the celiac plexus enter the medulla.

• These fibers are preganglionic and end on the medullary chromaffin cells.

HistologyAdrenal Cortex : • The vascularity of the adrenal cortex is among

the greatest in the entire body.• The adrenal cortex is composed of three zones:

the zona glomerulosa, the zona fasciculata, and the zona reticularis.

• In all three zones, all cells produce steroids. • In the zona glomerulosa (the outermost layer),

small cells are arranged in roughly spherical groups. This zone secretes the mineralocorticoid aldosterone.

• In the zona fasciculata, larger cells are arranged in columns which are oriented radially.

• The carbohydrate-active steroid, cortisol, and the adrenal sex steroids are produced here. Vitamin C is abundant in these cells.

• In the third layer, the zona reticularis, small cells are arranged in strands forming an irregular network.

• These cells secrete cortisol, androgens, and estrogens. Cholesterol is present as a precursor to the genesis of the steroids.

Adrenal Medulla

• The cells in the adrenal medulla are large and pale. They secrete epinephrine and have a chromaffin reaction. These cells are called chromaffin cells, or pheochromocytes.

• Distributed throughout the medulla, but few in number, are postganglionic sympathetic neurons.

• Most medullary cells secrete epinephrine, but some secrete norepinephrine instead.

AdrenelectomyIndications for Adrenelectomy :Unilateral1) Aldosteronoma2) Cortisol secreting Adenoma (Cushing syndrome)3) Unilateral pheochromocytoma4) Virilizing or feminizing tumours5) Non functioning unilateral tumors

(Size >4-5 cm)6) Adrenalcortical carcinomas7) Solitary unilateral metastasis.

Adrenelectomy Bilateral 1)Bilateral pheochromocytoma.2) Cushing syndrome due to B/L nodular adrenal hyperplasia.3) Cushing’s disease (pituitary tumour) unsuccessfully treated by surgery or radiation.

Anterior Approach for Left Adrenalectomy

Exposure and Mobilization of Left Adrenal Gland

Anterior Approach for Right Adrenalectomy

• On the right, the anterior approach to the adrenal gland begins with the mobilization of the hepatic flexure of the colon.

• Mobilization of the colon will expose the duodenum. The second portion of the duodenum is freed by incision of its lateral avascular peritoneal reflection.

• It can now be separated from retroperitoneal structures and reflected forward and to the left (Kocher maneuver).

Posterior Approach for Adrenalectomy

Thoracoabdominal Approach for Adrenalectomy

Laparoscopic Adrenelectomy

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