kidney anatomy

Where are the kidneys located in the body?

They sit retroperitoneally from about T12 to L3.

How many kidneys are there and which one sits lower?

Two kidneys; the right kidney sits lower than the left.

What gland sits on top of each kidney?

The adrenal (suprarenal) gland.

What are the three layers surrounding the kidney (from outermost to innermost)?

Pararenal fat, renal fascia, adipose capsule, and renal capsule.

What is the pararenal (paranephric) fat?

The outermost layer of fat surrounding the kidney.

What is the renal fascia?

A superficial layer of dense irregular connective tissue that binds the kidneys to the abdominal wall.

What is the adipose capsule?

The middle layer of fat that cushions and protects the kidneys.

What is the renal capsule?

The deepest layer, made of dense irregular connective tissue that encloses the kidney.

What is the renal parenchyma?

The functional portion of the kidney; glandular tissue that forms urine and encircles the renal sinus.

What are the two main regions of the renal parenchyma?

The cortex (outer) and medulla (inner).

What are renal columns?

Extensions of cortical tissue between the renal pyramids.

What are renal pyramids?

Cone-shaped structures in the medulla that contain collecting ducts.

What is the renal papilla?

The apex (tip) of a renal pyramid where urine drains into a minor calyx.

What is a minor calyx?

A cup-like structure that collects urine from a single renal papilla.

What is a major calyx?

A structure formed by the merging of several minor calyces.

What is the renal pelvis?

A funnel-shaped reservoir that collects urine from major calyces and leads to the ureter.

What is the hilum of the kidney?

The medial indentation where vessels, nerves, and the ureter enter or exit the kidney.