Kidneys and Suprarenal Glands

Kidneys and Suprarenal Glands

Kidneys and Suprarenal Glands

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Kidneys - Bean Scene Investigation

  • Location: Retroperitoneal, T12-L3. Right kidney typically lower. Hilum of left kidney near transpyloric plane (L1).
  • Size & Weight: Approx. 11x6x3 cm; 135-150 g.
  • Coverings (inward to outward):
    • Fibrous capsule (true capsule)
    • Perirenal fat (adipose capsule)
    • Renal fascia (Gerota's fascia) - encloses kidney & suprarenal gland (separated by a thin septum)
    • Pararenal fat (posteriorly)
  • Posterior Relations: Diaphragm, Transversus abdominis, Iliacus, Psoas major, Quadratus lumborum muscles; Subcostal (T12), Iliohypogastric (L1), & Ilioinguinal (L1) nerves/vessels. 📌 Mnemonic: 'D TITS L'.
  • Anterior Relations:
    Right KidneyLeft Kidney
    Suprarenal, Liver, Duodenum (2nd)Suprarenal, Stomach, Spleen
    Hepatic flexure (Colon), JejunumPancreas (tail), Splenic flexure (Colon), Jejunum

⭐ The hilum of the left kidney lies near the transpyloric plane (L1), about 5 cm from the midline.

Kidney anterior and posterior relations Renal fascia and surrounding structures

Kidneys - Inside Story & Plumbing

  • Hilum: Structures anterior to posterior: Renal Vein, Renal Artery, Renal Pelvis (VAP 📌).
  • Renal Sinus: Fat-filled central cavity; houses renal vessels, nerves, calyces, and pelvis.
  • Internal Structure:
    • Outer Cortex: Contains glomeruli, convoluted tubules, cortical collecting ducts. Extends into medulla as renal columns of Bertin.
    • Inner Medulla: Composed of 8-18 renal pyramids; apex is renal papilla, projecting into a minor calyx. Each papilla drains into one of 7-14 minor calyces.
  • Collecting System (Urine Flow): Minor calyces merge to form 2-3 major calyces, then the renal pelvis.
  • Renal Segments: 5 segments based on arterial supply: Apical, Anterosuperior, Anteroinferior, Posterior, Inferior.

Coronal section of kidney with labeled structures

⭐ Renal columns (of Bertin) are inward extensions of cortical tissue that separate the renal pyramids.

Kidneys - Red Rivers & Wires

  • Arterial Supply: Abd. Aorta (L1-L2) → Renal arteries → 5 Segmental (end arteries) → Lobar → Interlobar (renal columns) → Arcuate (corticomedullary jn.) → Interlobular (cortex) → Afferent arterioles.
  • Venous Drainage: Stellate veins → Interlobular → Arcuate → Interlobar → Segmental → Renal vein → IVC.
    • 📌 Left renal vein: longer, anterior to Aorta, posterior to SMA; receives left suprarenal & gonadal veins.
  • Lymphatics: Lateral aortic (paraaortic/lumbar) nodes.
  • Nerves: Renal plexus (around renal artery).
    • Sympathetic (T10-L1/L2, least splanchnic): vasoconstriction, ↑ renin.
    • Parasympathetic (Vagus): function less clear.

⭐ The segmental arteries of the kidney are anatomical end arteries; their occlusion can lead to infarction of the renal segment they supply.

Suprarenals - Adrenal Rush Hour

  • Location: Retroperitoneal, superomedial to kidneys, within renal fascia (but separate).
  • Shape: Right: pyramidal; Left: semilunar.
  • Parts & Origin:
    • Cortex (mesoderm): 📌 Mnemonic 'GFR - Salt, Sugar, Sex'
      ZoneProduct (e.g.)Primary Role
      GlomerulosaMineralocorticoids (Aldosterone)Salt balance
      FasciculataGlucocorticoids (Cortisol)Sugar metabolism
      ReticularisAndrogensSex hormones
    • Medulla (neural crest): Chromaffin cells (modified postganglionic sympathetic neurons) secrete Catecholamines (Adrenaline, Noradrenaline).
  • Arterial Supply (Rich): 📌 Superior (from inferior phrenic a.), Middle (from abdominal aorta), Inferior (from renal a.).
  • Venous Drainage (Single vein/gland): 📌 Right suprarenal v. → IVC; Left suprarenal v. → Left renal v.
  • Lymphatics: Lumbar (para-aortic) nodes.
  • Nerve Supply: Preganglionic sympathetic fibers (splanchnic nerves) to medullary chromaffin cells. Kidneys and suprarenal glands with arterial supply

⭐ The left suprarenal vein drains into the left renal vein, then to IVC; the right suprarenal vein drains directly into the IVC.

High‑Yield Points - ⚡ Biggest Takeaways

  • Kidneys: Retroperitoneal, T12-L3 level; right kidney slightly lower.
  • Renal hilum (anterior to posterior): Vein, Artery, Pelvis (VAP).
  • Left suprarenal veinleft renal vein; Right suprarenal veinIVC.
  • Suprarenal cortex (GFR): Glomerulosa (Aldosterone), Fasciculata (Cortisol), Reticularis (Androgens).
  • Suprarenal medulla: Chromaffin cells secrete catecholamines.
  • Nutcracker syndrome: Left renal vein compression by SMA and Aorta.
  • Horseshoe kidney: Ascent blocked by Inferior Mesenteric Artery.

Practice Questions: Kidneys and Suprarenal Glands

Test your understanding with these related questions

The aortic hiatus is formed by the right and left crura of the diaphragm. Which of the following structures does NOT pass through the aortic hiatus?

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Flashcards: Kidneys and Suprarenal Glands

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Right adrenal gland is _____ in shape while the left adrenal gland is semi-lunar/crescent shaped.

TAP TO REVEAL ANSWER

Right adrenal gland is _____ in shape while the left adrenal gland is semi-lunar/crescent shaped.

pyramidal

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