Post on 31-Jul-2015
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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