URINARY TRACT Lecture – Anatomy Lectures – MBBS Lectures

• The kidneys produce urine that is conveyed by the ureters to the urinary bladder in the pelvis. The superomedial aspect of each kidney normally contacts a suprarenal gland.
• The urinary tract consists of the kidneys, ureters, urinary bladder, and urethra.

KIDNEYS

• The ovoid kidneys remove excess water, salts, and wastes of protein metabolism from the blood while returning nutrients and chemicals to the blood.
• The two kidneys function to excrete most of the waste products of metabolism.
• They play a major role in controlling the water and electrolyte balance within the body and in maintaining the acid–base balance of the blood.

Location and Description

• The kidneys are reddish brown and lie retroperitoneally, high up on the posterior abdominal wall on either side of the vertebral column; at the level of T12 to L3 vertebrae.
• They are largely under cover of the costal margin.
• The right kidney lies slightly lower than the left kidney because of the large size of the right lobe of the liver. With contraction of the diaphragm during respiration, both kidneys move downward in a vertical direction by as much as 1 inch.

GROSS FEATURES

• The hilum is a vertical slit in the medial concave border of each kidney that is bounded by thick lips of renal substance. The hilum extends into a large cavity called the renal sinus.
• The hilum transmits, from the front backward, the renal vein, two branches of the renal artery, the ureter, and the third branch of the renal artery (VAUA).

Renal Structure

Each kidney has a dark brown outer cortex and a light brown inner medulla.

Medulla:

• The medulla is composed of about a dozen renal pyramids, each having its base oriented toward the cortex and its apex, the renal papilla, projecting medially.

Cortex:

• The cortex extends into the medulla between adjacent pyramids as the renal columns. Extending from the bases of the renal pyramids into the cortex are striations known as medullary rays.

Renal Pelvis:

• The renal pelvis is the flattened, funnel-shaped expansion of the superior end of the ureter. The renal pelvis receives two or three major calices (calyces), each of which divides into two or three minor calices.
  • Each minor calyx is indented by a renal papilla, the apex of the renal pyramid, from which the urine is excreted.

Coverings

The kidneys have the following coverings:

1. Fibrous capsule: This surrounds the kidney and is closely applied to its outer surface.
2. Perirenal fat: This covers the fibrous capsule.
3. Renal fascia: This is a condensation of connective tissue that lies outside the perirenal fat and encloses the kidneys and suprarenal glands; it is continuous laterally with the transversalis fascia.
4. Pararenal fat: This lies external to the renal fascia and is often in large quantity. It forms part of the retroperitoneal fat.

The perirenal fat, renal fascia, and pararenal fat support the kidneys and hold them in position on the posterior abdominal wall.

Renal Relations

Anterior Relations:

Posterior Relations:

Blood Supply:

Lymphatic Drainage:

Nerve Supply:

URETERS

• The ureters are muscular ducts (25–30 cm long) with narrow lumina that carry urine from the kidneys to the urinary bladder.
• They run inferiorly from the apices of the renal pelves at the hila of the kidneys, passing over the pelvic brim at the bifurcation of the common iliac arteries.
• They then run along the lateral wall of the pelvis and enter the urinary bladder.

It has three constrictions along its course:

• where the renal pelvis joins the ureter.
  • where it is kinked as it crosses the pelvic brim.
  • where it pierces the bladder wall.

Relations:

Blood Supply:

Lymphatics:

Clinicals

• Renal Mobility
• Perinephric Abscess
• Kidney Trauma
• Kidney Tumors
• Renal Pain
• Transplanted Kidneys
• Nephroptosis
• Renal Vein Entrapment Syndrome
• Congenital Anomalies of Kidneys and Ureters
• Renal and Ureteric Calculi

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