Overview
This lecture covers the external anatomy of the kidney, focusing on its blood supply, protective layers, distinguishing features, clinical correlations, and related anatomical relationships.
Kidney Vasculature & Position
- The abdominal aorta gives rise to the right and left renal arteries; the right artery is longer due to aorta’s left-side position.
- The left renal artery is shorter, while the left renal vein is longer because the inferior vena cava lies right of the midline.
- The right kidney sits lower than the left due to the presence of the liver in the upper right abdomen.
- Ureters exit the kidneys and transport urine to the urinary bladder, entering at the posterior aspect.
Kidney Orientation & Identification
- The concave surface of the kidney (renal hilum) faces medially, and the convex surface faces laterally.
- The ureter drains downward from the renal pelvis, and blood vessels enter anterior to the renal pelvis.
Protective Layers & Supporting Structures
- The kidney is protected by the renal fascia (dense, fibrous tissue) and a pararenal fat capsule (adipose tissue).
- These layers anchor the kidney and cushion it from injury.
- In wasting diseases, loss of fat can lead to renal ptosis (kidney sagging), which may kink veins and cause hydronephrosis (fluid buildup).
Clinical Correlates & Risks
- Obesity or pregnancy can compress the left renal vein, leading to hydronephrosis and possible varicose veins (varices).
- Infections can ascend from the urethra, affecting the renal pelvis (pyelitis) and kidney (nephritis), often occurring together as pyelonephritis.
- The kidneys are retroperitoneal, meaning they are located behind the abdominal cavity.
Additional Anatomical Features
- The last two ribs (11 and 12) partially protect the kidneys, but the lower poles are vulnerable to trauma.
- The hilum is the entry/exit area for blood vessels and ureters within the kidney.
Key Terms & Definitions
- Renal artery — Blood vessel supplying blood to the kidney.
- Renal vein — Blood vessel draining blood from the kidney.
- Ureter — Tube carrying urine from kidney to bladder.
- Renal pelvis — Funnel-shaped structure draining urine into the ureter.
- Renal fascia — Outer fibrous tissue anchoring the kidney.
- Pararenal fat capsule — Fat layer protecting and cushioning the kidney.
- Renal ptosis — Drooping of the kidney due to fat loss.
- Hydronephrosis — Swelling of the kidney from urine or fluid buildup.
- Pyelonephritis — Inflammation/infection of the kidney and renal pelvis.
- Hilum — Area where blood vessels and ureter enter/exit the kidney.
- Retroperitoneal — Located behind the peritoneal cavity.
Action Items / Next Steps
- Review diagrams of kidney anatomy and surrounding vasculature.
- Read textbook sections on external kidney anatomy, focusing on protective layers and clinical correlations.
- Look up terms such as pyelonephritis, hydronephrosis, and renal ptosis for further understanding.