The Kidney
Position and relations
The kidneys lie retroperitoneally in the upper posterior abdomen. The position and relations are
different for the two sides.
The right kidney
The right kidney lies on the
posterior abdominal wall so that the twelfth rib passes posteriorly
across its upper pole. Its posterior surface is therefore related to the diaphragm above the twelfth
rib, and the quadratus lumborum muscle below the twelfth rib. Laterally the transversus
abdominis muscle curves anteriorly. The medial surface of the kidney faces anteromeduilly
towards the psoas muscle. The anterior
surface of the right kidney is related to the liver,
duodenum and ascending colon. The kidney has a strong capsule but is further invested in
transversalis fascia. The fascia fuses at the medial border of the kidney around the vessels.
Inferiorly the fascia continues into the pelvis around the ureter. Blood or urine entering the fascial
compartment of the kidney can track down into the pelvis around the ureter. There is a thick
layer of fat, the perirenal fat, enclosed by the transversalis fascia. The right adrenal gland is
pyramidal in shape and sits on the upper pole.
The left kidney
The left kidney is usually slightly
higher than the right. The twelfth rib passes posteriorly behind
the lower part of the upper pole. The eleventh rib may be a posterior relation just at the tip of the
upper pole. As for the right kidney the diaphragm and quadratus lumborum are posterior
relations. The medial border of the left kidney is as for the right related to the psoas muscle.
Anteriorly the left kidney is
related to the spleen, stomach, pancreas, jejunum and descending
colon. The transversalis fascia takes the same form as for the right kidney. The left adrenal gland
sits as a crescent shaped cap on the medial surface of the upper pole.
Kidney imaging
The kidneys can be viewed on radiographic or ultrasound
images. By CT the position and relations of the kidneys can be seen.
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