Adrenal gland anatomy

Overview

• Lie anterosuperior to the upper part of each kidney
• Lie within their own compartment of the Renal Fascia

Right Suprarenal Gland

• Shape: Pyramidal
• Lies on the Diaphragm (NB: Right Crus)
• Encroaches onto the front of the Right Kidney
• Anterior surface
  • Overlapped medially by the Inferior Vena Cava
  • Rest of anterior surface in contact above with the Bare Area of the Liver
  • Covered below by Peritoneum of the posterior wall of the Hepatorenal Pouch

Left Suprarenal Gland

• Shape: Crescentic
• Drapes over the medial border of the Left Kidney above the Hilum
• Lies on the Left Crus of the Diaphragm
• Overlaps the front of the Left Kidney
• Anterior surface:
  • Upper part covered by Peritoneum of the posterior wall of the Lesser Sac forming part of the Stomach Bed
  • Lower part – in contact with the body of the Pancreas and the Splenic Vessels

Blood Supply

• 3 Sources
  1. Directly from the Aorta
  2. Renal Artery
  3. Inferior Phrenic Artery
• Venous Drainage
  • Left - Adrenal Vein to Left Renal Vein
  • Right – Adrenal Vein to IVC (short)
  • Veins drain Adrenal Medulla
  • Cortical drainage through medulla

Lymphatic Drainage

• To Para-aortic Lymph Nodes

Nerve Supply

• Medulla
  • Main supply – myelinated pre-ganglionic sympathetic fibres from the Splanchnic nerves via the Coeliac Plexus
    • Synapse directly with Medullary Cells
  • Blood vessels receive usual Post-Ganglionic Sympathetic fibres
  • Richly supplied by Splanchnic Fibres (T5-9)
    • Can be regarded as modified sympathetic ganglion
      • Axon replaced by secretory cells
        • Chromaffin cells/phaeochromcytes
        • Filled with granules containing catecholamines
• Cortical
  • Hormone driven e.g. ACTH from the Anterior Pituitary Gland causes release of cortisol

Structure

• Outer yellow cortex enclosing thinner grey medulla
• Cortex
  • Produces cortisol, aldosterone, androgens and related hormones
  • 3 layers/zones
    • Zona Glomerulosa – small, rounded cells
    • Zona Fasciculata – parallel rows of pale-staining vacuolated cells
    • Zona Reticularis – smaller and darker-staining cells
• Medulla
  • Larger cells secreting catecholamines adrenaline (epinephrine) (80%) and noradrenaline (norepinephrine) (20%) and some dopamine
  • Many medullary cells exhibit chromaffin reaction – contain fine cytoplasmic granules (catecholamine precursors) which are coloured brown by chromium salts
  • Dilated capillaries prominent (unlike the cortex)
  • NB: Contains cells equivalent to post-ganglionic neurones

Microscopic Anatomy

Zona Glomerulosa

• Columnar cells, relatively little cytoplasm compared to nuclei, organised in clusters
• Produces mineralocorticoids

Zona Fasciculata – (75% of Cortex)

• Poorly staining polyhedral cells, organised in radial columns
• Primarily produces glucocorticoids

Zone Reticularis

• Rounded branching cords of cells
• Produce sex hormones, particularly DHEAS

Medulla – 15% volume

• Vascular spaces
• Eosinophilic phaeochromocytes with polymorphic nuclei
• Uptake dichromate – “Chromaffin cells”

Surgical Approach

• Bilateral adrenalectomy
  • Glands approached from the front
  • Anterior transperitoneal approach also used for laparoscopic bilateral adrenalectomy
  • Bilateral subcostal rooftop incision
  • Transperitoneal access
  • Exposing Right Suprarenal Gland:
    • Reaction of Right Lobe of Liver
    • Kocher Manoeuvre to mobilize 2nd part of Duodenum and Head of Pancreas from the upper pole of the Kidney and Inferior Vena Cava
  • Exposing the Left Suprarenal Gland:
    • Divide Phrenicocolic Ligament to mobilize Splenic Flexure of the Colon
    • Posterior layer of the Splenorenal Ligament incised
    • Spleen turned medially with the Tail of the Pancreas
  • On each side – Adrenal Vein ligated before the numerous small arteries
    • Right vein particularly short and Inferior Vena Cava easily torn
  • Glands must be handled as little as possible before venous ligation to prevent surges of hormone release
• Posterior extraperitoneal approach
  • Through bed of 12th Rib
  • Provides access for unilateral adrenalectomy
  • Removal of a large adrenal tumour may require a higher approach – through the bed of the 11th or 10th Ribs and division of the Diaphragm