{"id":4422379,"date":"2025-01-11T15:44:25","date_gmt":"2025-01-11T21:44:25","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/adrenal-gland-anatomy\/"},"modified":"2025-01-12T18:27:20","modified_gmt":"2025-01-13T00:27:20","slug":"adrenal-gland-anatomy","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/adrenal-gland-anatomy\/","title":{"rendered":"Adrenal Gland Anatomy"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">DEVELOPMENT OF THE ADRENAL GLANDS<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Historical Note<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>First detailed anatomic description<\/strong> by Bartholomeo Eustacius in 1563.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Overview<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Each adrenal gland consists of:\n<ul class=\"wp-block-list\">\n<li><strong>Cortex<\/strong>: Derived from <strong>mesenchymal tissue<\/strong>.<\/li>\n\n\n\n<li><strong>Medulla<\/strong>: Derived from <strong>ectodermal neural crest<\/strong> tissue.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Both parts are enveloped in a <strong>common capsule<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Cortical Development<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Early Embryogenesis (5th\u20136th Week)<\/strong>\n<ul class=\"wp-block-list\">\n<li>Proliferation of <strong>mesenchymal (coelomic)<\/strong> cells adjacent to the urogenital ridge \u2192 <strong>primitive cortex<\/strong>.<\/li>\n\n\n\n<li>These cells penetrate retroperitoneal mesenchyme and form a fetal cortical mass.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Permanent <a href=\"https:\/\/myendoconsult.com\/learn\/the-formation-and-structure-of-the-adrenal-cortex\/\" data-wpil-monitor-id=\"150\">Cortex Formation<\/a><\/strong>\n<ul class=\"wp-block-list\">\n<li>Soon after the primitive cortex forms, a thin outer layer of cells (from the same mesodermal source) envelops it \u2192 <strong>permanent cortex<\/strong>.<\/li>\n\n\n\n<li>By the <strong>8th week<\/strong>, the forming cortex is in intimate contact with the <strong>cranial pole of the kidney<\/strong> and invests in a connective tissue capsule.<\/li>\n\n\n\n<li>This early adrenal is very large compared to the kidney.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Fetal vs. Permanent Cortex<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Fetal (Primitive) Cortex<\/strong>: Major bulk of the gland at birth; rapidly involutes after birth.\n<ul class=\"wp-block-list\">\n<li>By 2 weeks postpartum, the glands lose ~1\/3 of their weight.<\/li>\n\n\n\n<li>The fetal cortex fully disappears by the end of the first year.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Permanent (Outer) Cortex<\/strong>: Thin at birth; differentiates further once fetal cortex involutes.\n<ul class=\"wp-block-list\">\n<li>Full zonal differentiation (glomerulosa, fasciculata, reticularis) completes around the <strong>3rd year of life<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Role of Transcription Factors<\/strong>\n<ul class=\"wp-block-list\">\n<li>Differentiation dependent on temporal expression of genes (e.g., <strong>steroidogenic factor 1<\/strong>, <strong>zona glomerulosa\u2013specific protein<\/strong>, <strong>inner zone antigen<\/strong>).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Medullary Development<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Neural Crest Origin<\/strong>\n<ul class=\"wp-block-list\">\n<li>Ectodermal cells from neural crest migrate to form <strong>sympathetic neurons<\/strong> (autonomic system).<\/li>\n\n\n\n<li>Some neural crest cells differentiate into <strong>chromaffin cells<\/strong> instead of neurons.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Chromaffin Cells<\/strong>\n<ul class=\"wp-block-list\">\n<li>Named for their brown staining with chromium salts (oxidation of catecholamines).<\/li>\n\n\n\n<li>Migrate from <strong>primitive autonomic ganglia<\/strong> adjacent to the developing cortex into the adrenal to form the <strong>medulla<\/strong> (7th week onward).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Paraganglia and Organ of Zuckerkandl<\/strong>\n<ul class=\"wp-block-list\">\n<li>Some chromaffin cells remain outside the adrenals \u2192 <strong>paraganglia<\/strong> along the aorta.<\/li>\n\n\n\n<li><strong>Organ of Zuckerkandl<\/strong>: A large paraganglion near the inferior mesenteric artery; prominent in fetuses, a key extra-adrenal catecholamine source in infancy.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Accessory and Absent Glands<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>True Accessory Adrenal Glands<\/strong> (cortex + medulla) are rare; can be found in celiac plexus or kidney cortex.<\/li>\n\n\n\n<li><strong>Adrenal \u201cRests\u201d<\/strong> (usually cortical only) may occur near the main gland or in retroperitoneum, spleen, etc.<\/li>\n\n\n\n<li><strong>Gonadal Proximity<\/strong> during embryonic life \u2192 ectopic adrenal tissue may appear in the <strong>spermatic cord, scrotum, ovary, or broad ligament<\/strong>.<\/li>\n\n\n\n<li><strong>Absent Adrenal Gland<\/strong> on one side can occur but <strong>bilateral absence<\/strong> is extremely rare.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">ANATOMY AND BLOOD SUPPLY OF THE ADRENAL GLANDS<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Location and Gross Anatomy<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Retroperitoneal<\/strong>\n<ul class=\"wp-block-list\">\n<li>At the <strong>upper poles of the kidneys<\/strong>.<\/li>\n\n\n\n<li>Level of ~T11 rib to L1 vertebra; each weighs ~3.5\u20136 g.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Capsule and Appearance<\/strong>\n<ul class=\"wp-block-list\">\n<li>Surrounded by <strong>areolar (fatty) tissue<\/strong>; covered by a thin fibrous capsule.<\/li>\n\n\n\n<li><strong>Golden-yellow<\/strong> cortical tissue on section; <strong>reddish-brown<\/strong> medullary center.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Right Adrenal Gland<\/strong>\n<ul class=\"wp-block-list\">\n<li>Triangular (\u201cpyramidal\u201d) shape.<\/li>\n\n\n\n<li>Higher and more lateral; close to right diaphragmatic crus.<\/li>\n\n\n\n<li>Surrounded by liver (anterosuperiorly), IVC (medially), upper pole of the right kidney (inferolaterally).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Left Adrenal Gland<\/strong>\n<ul class=\"wp-block-list\">\n<li>Elongated or semilunar shape, slightly larger.<\/li>\n\n\n\n<li>Often overlaps the lateral border of the aorta.<\/li>\n\n\n\n<li>Posterior surface adjacent to diaphragm, splanchnic nerves.<\/li>\n\n\n\n<li>Upper 2\/3 behind lesser sac; lower 1\/3 near pancreas body and splenic vessels.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1405\" height=\"929\" src=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/adrenal-vascular-supply-and-AVS.jpg\" alt=\"\" class=\"wp-image-4417743\" srcset=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/adrenal-vascular-supply-and-AVS.jpg 1405w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/adrenal-vascular-supply-and-AVS-300x198.jpg 300w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/adrenal-vascular-supply-and-AVS-768x508.jpg 768w\" sizes=\"auto, (max-width: 1405px) 100vw, 1405px\" \/><figcaption class=\"wp-element-caption\">Anatomy of the Adrenal Gland<\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Blood Supply<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Arterial Supply<\/strong>: Extremely rich and variable, with 12 or more small arterial branches.\n<ul class=\"wp-block-list\">\n<li><strong>Superior Adrenal Artery<\/strong> (from <strong>inferior phrenic<\/strong>),<\/li>\n\n\n\n<li><strong>Middle Adrenal Artery<\/strong> (from <strong>aorta<\/strong>),<\/li>\n\n\n\n<li><strong>Inferior Adrenal Artery<\/strong> (from <strong>renal artery<\/strong>).<\/li>\n\n\n\n<li>Arteries encircle the gland, forming a network to supply cortex and medulla.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Venous Drainage<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Right <a href=\"https:\/\/myendoconsult.com\/learn\/localization-of-source-of-hyperaldosteronism-adrenal-vein-sampling\/\" data-wpil-monitor-id=\"147\">Adrenal Vein<\/a><\/strong> \u2192 directly into <strong>IVC<\/strong>; ~4\u20135 mm long.<\/li>\n\n\n\n<li><strong>Left <a href=\"https:\/\/myendoconsult.com\/learn\/adrenal-vein-sampling-interpretation\/\" data-wpil-monitor-id=\"148\">Adrenal Vein<\/a><\/strong> \u2192 <strong>left renal vein<\/strong> (often joined by left inferior phrenic vein).<\/li>\n\n\n\n<li>Both adrenals have a single large central vein that collects blood from cortex &amp; medulla.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Adrenal Vasculature Integration<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Cortical-&gt;Medullary Flow<\/strong>\n<ul class=\"wp-block-list\">\n<li>Cortisol-rich blood from cortical sinusoids flows into medullary sinusoids.<\/li>\n\n\n\n<li>Enhances phenylethanolamine-N-methyltransferase (PNMT) activity, converting norepinephrine to <strong>epinephrine<\/strong> in medulla.<\/li>\n\n\n\n<li>Extra-adrenal chromaffin sites lack this high cortisol \u2192 produce mostly norepinephrine.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Surgical Approaches to the Adrenal Glands<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Open Transabdominal<\/strong>\n<ul class=\"wp-block-list\">\n<li>Incision: Extended subcostal or midline (for bilateral disease).<\/li>\n\n\n\n<li>Left adrenal: via <strong>gastrocolic ligament<\/strong> into lesser sac \u2192 mobilize pancreas, open Gerota fascia, retract kidney.<\/li>\n\n\n\n<li>Right adrenal: mobilize hepatic flexure, retract right liver lobe upward.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Open Posterior<\/strong>\n<ul class=\"wp-block-list\">\n<li>Patient prone; less postoperative pain, reduced ileus.<\/li>\n\n\n\n<li>Curvilinear incision (10th rib to iliac crest) or resection of 12th rib. Access behind kidney.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Laparoscopic Transabdominal<\/strong>\n<ul class=\"wp-block-list\">\n<li>Standard approach for unilateral masses &lt;8 cm with no suspicion of invasive malignancy.<\/li>\n\n\n\n<li>Patient lateral decubitus; typically 4 trocars below costal margin.<\/li>\n\n\n\n<li>Right side: Retract liver; left side: mobilize colonic flexure.<\/li>\n\n\n\n<li>Lower morbidity, faster recovery.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Posterior Retroperitoneoscopic<\/strong>\n<ul class=\"wp-block-list\">\n<li>Patient prone, 3 trocars in flank.<\/li>\n\n\n\n<li>Insufflation of retroperitoneal space (20\u201325 mm Hg).<\/li>\n\n\n\n<li>Good for patients with prior abdominal surgeries (no adhesions).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Keys to Success<\/strong>\n<ul class=\"wp-block-list\">\n<li>Careful patient selection, knowledge of anatomy, gentle tissue handling, meticulous hemostasis, awareness of vascular anomalies.<\/li>\n\n\n\n<li>Adrenal parenchyma is fragile.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">INNERVATION OF THE ADRENAL GLANDS<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Sympathetic Innervation<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Preganglionic Fibers<\/strong>\n<ul class=\"wp-block-list\">\n<li>Arise from T11\u2013L2 spinal cord segments (lateral horns).<\/li>\n\n\n\n<li>Travel via <strong>white rami<\/strong> \u2192 <strong>splanchnic nerves<\/strong> (greater, lesser, least) \u2192 celiac, aorticorenal, renal ganglia.<\/li>\n\n\n\n<li>Many fibers <strong>pass through<\/strong> these ganglia without synapsing \u2192 form <strong>adrenal plexus<\/strong> on the gland\u2019s medial border.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Medullary Innervation<\/strong>\n<ul class=\"wp-block-list\">\n<li>Preganglionic fibers terminate directly on <strong>chromaffin cells<\/strong> (equivalent to postganglionic sympathetic neurons).<\/li>\n\n\n\n<li>Some small ganglia exist within medulla or near vessels.<\/li>\n\n\n\n<li>Parasympathetic supply from the <strong>celiac branch of posterior vagal trunk<\/strong> may also reach the adrenal plexus.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Functional Significance<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chromaffin Cells<\/strong> (in medulla) release <strong>epinephrine<\/strong>, <strong>norepinephrine<\/strong>, and dopamine.<\/li>\n\n\n\n<li><strong>Fight-or-Flight Response<\/strong> triggered by hypothalamus, pons, medulla \u2192 sympathetic outflow to T\/L spine \u2192 adrenal medulla.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">HISTOLOGY OF THE ADRENAL GLANDS<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Cortex and Medulla<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Cortex<\/strong> (~90% of adult adrenal)\n<ul class=\"wp-block-list\">\n<li>Embryological origin: <strong>Mesoderm<\/strong>.<\/li>\n\n\n\n<li>3 Zones: <strong><a href=\"https:\/\/myendoconsult.com\/learn\/the-zona-glomerulosa-of-the-adrenal-gland\/\" data-wpil-monitor-id=\"151\">Zona glomerulosa<\/a>, fasciculata, reticularis<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Medulla<\/strong> (~10% of adult adrenal)\n<ul class=\"wp-block-list\">\n<li>Embryological origin: <strong>Neural crest<\/strong>.<\/li>\n\n\n\n<li>Contains <strong>chromaffin cells<\/strong> producing catecholamines (epinephrine &gt; norepinephrine).<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Adrenal Cortex Details<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Zona Glomerulosa<\/strong>\n<ul class=\"wp-block-list\">\n<li>Outer thin layer: cells arranged in loops or \u201cglomeruli.\u201d<\/li>\n\n\n\n<li>Secretes <strong><a href=\"https:\/\/myendoconsult.com\/learn\/topics\/aldosteronism\/\"  data-wpil-monitor-id=\"339\">aldosterone<\/a><\/strong> (mineralocorticoid), regulates Na\u207a\/K\u207a balance.<\/li>\n\n\n\n<li>Largely independent of ACTH; controlled by <strong>renin\u2013angiotensin<\/strong> system.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong><a href=\"https:\/\/myendoconsult.com\/learn\/zona-fasciculata-of-the-adrenal-gland\/\" data-wpil-monitor-id=\"152\">Zona Fasciculata<\/a><\/strong>\n<ul class=\"wp-block-list\">\n<li>Middle broad layer: cells in long straight cords (\u201cfascicles\u201d), rich in lipid vacuoles.<\/li>\n\n\n\n<li>Produces <strong>cortisol<\/strong> (glucocorticoid).<\/li>\n\n\n\n<li>Dependent on pituitary ACTH.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Zona Reticularis<\/strong>\n<ul class=\"wp-block-list\">\n<li>Inner layer next to medulla, cords form reticular network.<\/li>\n\n\n\n<li><a href=\"https:\/\/myendoconsult.com\/learn\/bilateral-cortisol-secreting-tumors\/\" data-wpil-monitor-id=\"149\">Secretes cortisol<\/a> and some <strong>adrenal androgens<\/strong> (e.g., DHEA).<\/li>\n\n\n\n<li>Also dependent on ACTH.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Blood Supply<\/strong>\n<ul class=\"wp-block-list\">\n<li>30\u201350 small arteries \u2192 capsular plexus \u2192 radial capillaries in cortex \u2192 drains into medullary sinusoids \u2192 single central <a href=\"https:\/\/myendoconsult.com\/learn\/adrenal-vein-sampling-testing-procedure\/\"  data-wpil-monitor-id=\"340\">adrenal vein<\/a>.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Adrenal Medulla Details<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Columnar Chromaffin Cells<\/strong>\n<ul class=\"wp-block-list\">\n<li>Produce <strong>epinephrine<\/strong> (\u223c80%) and <strong>norepinephrine<\/strong> (\u223c20%), small amounts of dopamine.<\/li>\n\n\n\n<li>Stain brown with chromium salts (oxidation of catecholamines).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Direct Sympathetic Innervation<\/strong>\n<ul class=\"wp-block-list\">\n<li>Preganglionic fibers release ACh onto chromaffin cells \u2192 catecholamine secretion.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Vessels<\/strong>\n<ul class=\"wp-block-list\">\n<li>Arterial supply from short cortical arteries passing straight into medulla + venous outflow from cortical sinusoids.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>DEVELOPMENT OF THE ADRENAL GLANDS Historical Note Overview Cortical Development Medullary Development Accessory and Absent Glands ANATOMY AND BLOOD SUPPLY OF THE ADRENAL GLANDS Location and Gross Anatomy Blood Supply Adrenal Vasculature Integration Surgical Approaches to the Adrenal Glands INNERVATION OF THE ADRENAL GLANDS Sympathetic Innervation Functional Significance HISTOLOGY OF THE ADRENAL GLANDS Cortex and [&hellip;]<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[684],"class_list":["post-4422379","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-adrenal-gland","post-wrapper","thrv_wrapper"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422379","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":5,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422379\/revisions"}],"predecessor-version":[{"id":4422828,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422379\/revisions\/4422828"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422379"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}