kidney anatomy | internal and external anatomy

Anatomy of kidney

The kidneys lie on the back of the peritoneum in the posterior abdominal wall on either side of the vertebral column. Kidneys are partially protected by the lumber vertebrae and rib cage. Left kidney is little bit higher than right kidney. The Liver is present above the right kidney and pushes it slightly lower than the left.  Each kidney is about 11 cm long, 5 cm wide, and 3 cm thick and about 130g in weight.

External anatomy of kidney

Renal capsule

it is a layer of fibrous connective tissue which surrounds each kidney.

Perirenal fat

it is a dense layer of adipose tissue which surrounds renal capsule and functions as cushion against mechanical shock.

Renal fascia

It is a thin layer of connective tissue, anchors kidneys to the abdominal wall.

Hilum

Renal artery and nerves enter, and renal vein and ureter leave kidneys.

Internal anatomy of kidney

The kidneys have two major regions:

1: Outer cortex

2: Inner medulla

The medulla consists of cone shaped structures known as renal pyramids. Medullary rays extend into the cortex from the renal pyramids.

Renal columns, composed of cortical tissue, are present between the renal pyramids. The tips of the pyramids known as the renal papillae, point toward the renal sinus.

the renal papillae extend into minor calyces which are funnel-shaped chambers. The minor calyces of several pyramids combine to form larger funnels called the major calyces.

 Each kidney consists of 8–20 minor calyces and 2 or 3 major calyces.  The major calyces converge, and they form an enlarged chamber known as renal pelvis. Renal sinus surround the renal pelvis.

The renal pelvis narrows into a small-diameter tube known as ureter, which exits the kidney at the hilum and connects to urinary bladder. Urine formed inside the kidney passes from the renal papillae into the minor calyces. After passing from the minor calyces, urine flows into the major calyces and reaches the renal pelvis, and then leaves the kidney through the ureter.