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Renal anatomy diagram

Kidney Gross Anatomy

A Macroscopic View of Kidney Anatomy

Cortex, Medulla, and Capsule

A frontal section through the kidney reveals an outer, lighter-colored region called the renal cortex and an inner darker-colored region called the renal medulla. Surrounding the renal cortex is the renal capsule, a tough, fibrous layer of connective tissue that helps contain, support, and protect the kidney’s soft inner tissues.

Renal capsule, cortex, and medulla

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Lobes and Columns

Each kidney contains approximately 6–8 renal lobes, which can be seen without a microscope. A renal lobe contains thousands of microscopic tubules called nephrons, which are the kidney’s functional units.

Due to its shape, the medullary portion of a renal lobe is called a renal pyramid. A pyramid’s base (wide end) lies adjacent to the renal cortex, and the apex (narrow end) extends into the kidney’s medial indentation. A pyramid appears darker and somewhat striated because it contains a high concentration of straight, parallel tubules called collecting ducts, which transport urine to a lobe’s apex.

A renal column extends between and separates adjacent renal lobes. The columns largely consist of connective tissue and provide a supportive framework for blood vessels that enter and exit the cortex.

Renal pyramid, papilla, and column

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Hilum

The renal hilum is a recessed central fissure on the medial side of the kidney. It provides space for the passage of the renal blood vessels, nerves, and ureter.

Kidney anatomy: renal hilum

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Papilla, Calyces, Pelvis

The renal calyces are chambers of the kidney through which urine passes while traveling to the ureter. A minor calyx surrounds the apex of the renal pyramids. Urine formed in the kidney passes through a renal papilla at the apex into a minor calyx. Two or three minor calyces converge to form a major calyx, through which urine passes before continuing through the renal pelvis into the ureter. The smooth muscles in the calyces and renal pelvis walls rhythmically contract and relax (peristalsis) to propel urine into the ureter.

Kidney anatomy: renal papilla, calyces, and pelvis

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Major Arteries

Oxygenated blood enters the kidney from the descending aorta via the renal artery. In the renal hilum, the renal artery divides into segmental arteries, followed by further branching to form interlobar arteries, which pass through the renal columns toward the renal cortex. At the bases of the renal pyramids, the interlobar arteries branch into arcuate arteries, which extend along the arched intersections between the renal pyramids and cortex. Smaller vessels branch from the arcuate arteries and circulate blood throughout the renal lobes.

Kidney anatomy: major arteries

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Major Veins

The arcuate veins carry deoxygenated blood from smaller vessels in the renal lobes to the interlobar veins, which then pass through the renal columns and enter the renal hilum. Blood exits the kidney via the renal vein, which connects to the inferior vena cava.

Kidney anatomy: major arteries

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Assessment Quiz

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References and Attributions

OpenStax College, Anatomy and Physiology

Access for free athttps://openstax.org/books/anatomy-and-physiology/pages/1-introduction

Reference: “Gross Anatomy of the Kidney


Wikipedia, the free encyclopedia.

Reference 1: “Kidney

Reference 2: “Nephron