The kidneys are a pair of excretory organs located retroperitoneally on either side of the vertebral column. They remove waste and regulate water and electrolyte balance. Each kidney contains an inner medulla and outer cortex. The kidneys receive blood supply from the renal arteries and drain into the renal veins. They are important for regulating blood pressure and red blood cell production. Kidney diseases can cause hypertension, renal failure and require dialysis in severe cases.

2.  Kidneys are a pair of
excretory organs situated
on posterior abdominal
wall, one on each side of
vertebral column.
 They remove waste
products from the body and
main water and electrolyte
balance.
 In addition, the kidney
secrete renin for auto-
regulation of blood flow
and blood pressure,
erythropoietin for
maturation of red blood
cells, and 1,25-
hydroxycholecalciferol for
control of calcium
metabolism.

3.  Kidney occupy
epigastric,
hypochondriac,
lumbar and umbilical
regions.
 Vertically they
extend from upper
border of T12 to the
body of L3.
 The right kidney is
slightly lower than
left.
 Left kidney is slightly
nearer to median
plane than right.

4.  LONG AXIS- it is directed
downwards and laterally
so that upper end is
nearer to vertebral
column than lower end.
 TRANSVERSE AXIS- it is
directed laterally and
backwards because
kidney rest on sloping
paravertebral gutter of
muscles.
 Transpyloric plane
passes through upper
part of hilum of right
kidney and lower part of
hilum of left kidney.

5.  It is bean shaped.
 It has 2 poles- upper and
lower
 2 borders- medial and
lateral.
 2 surfaces- anterior and
posterior.
 It is reddish brown in
colour.

6.  2 POLES-
1. Upper pole is broad and is in close contact
with suprarenal gland.
2. Lower pole is pointed.

7.  2 SURFACES-
1. Anterior surface is irregular.
2. Posterior surface is flat.

8.  2 BORDERS-
1. Lateral border is convex.
2. Medial border is concave in its middle part,
it shows a depression called hilum.

9.  Following structures are seen
in hilum from anterior to
posterior side-
1. Renal vein
2. Renal artery
3. Renal pelvis

10. Average measurement of kidney-
 Length- 11 cm
 Breadth- 6 cm
 Thickness- 3 cm
 Weight- male- 150 g
female- 135 g

11.  Pressure exerted by neighboring viscera, this
is obtained by tone of abdominal muscles.
 By disposition of renal fascia and distribution
of renal fat.
 Pedicles of kidney attached to hilum.

12.  From within outwards-
1. Fibrous capsule (true capsule)
2. Perinephric fat (adipose capsule)
3. Renal fascia (false capsule or fascia of
Gerota)
4. Paranephric fat

13.  It is formed by
condensation of
fibrous stroma of
kidney.
 It covers entire
organ and lines
the wall of renal
sinus and is
reflected as
tubular sheaths
around major and
minor calyces and
pelvis of ureter.

14.  CLINICAL- in nephropexy operation to fix a
movable kidney, fibrous capsule is divided
along lateral border of kidney and rolled
posterior flap of capsule is sutured to the
last rib or muscles of posterior abdominal
wall.
 Decapsulation is occasionally made in
suppression of urine due to acute nephritis in
an attempt to release pressure on renal
tubules due to congestion or oedema.

15.  It occupies space between fibrous capsule
and renal fascia.
 Fat is abundant along borders of kidney and
is a content of renal sinus.

16.  It is formed by condensation of extra-peritoneal
connective tissue around the kidney and is continuous
with fascia transversalis.
 It consist of anterior and posterior layers.
 Anterior layer is thin and is known as fascia of Toldt.
 Posterior layer is thick and is known as fascia of
Zuckerkebdl.

17.  LATERALLY-
 Both layers fuse at lateral border and are continuous with
fascia transversalis.
 MEDIALLY-
 Anterior layer cover front of kidney and renal vessels and is
continuous with the anterior layer of opposite renal fascia in
front of aorta and IVC. This continuity is traceable up to
superior mesenteric artery.

18.  Posterior layer covers back of kidney and
renal vessels, blends with psoas fascia and is
attached to lumbar vertebrae.
 A deep stratum of fascia connects both layers
across hilum and thereby closes perinephric
space on medial side.

19.  ABOVE-
 Both layers fuse at upper end of kidney.
 BELOW-
 The two layers do not fuse, extend
downwards along the ureter and finally lost
in extra-peritoneal tissue of iliac fossa.

20.  It occupies interval between renal fascia and
anterior layer of thoraco-lumbar fascia and is
abundant on posterior surface of kidney.

21.  Kidneys are retro-
peritoneal and only
partially covered by
peritoneum anteriorly.
RELATIONS COMMON TO
BOTH KIDNEYS-
 Upper pole is related
to supra renal gland.
 Lower pole lie 2.5 cm
above the iliac crest.
 Medial border is
related to-
1. Supra renal gland
above hilum.
2. Ureter below the
hilum.

22.  Posterior relations-
1. Diaphragm
2. Medial and lateral arcuate ligament
3. Psoas major
4. Quadratus lumborum
5. Transversus abdominis
6. Subcostal vessels
7. Subcostal,
iliohypogastric
and ilioinguinal
nerves.

23.  Other relations of right
kidney-
 Anterior relations-
1. Supra renal gland
2. Liver
3. Second part of
duodenum
4. Hepatic flexure of
colon
5. Small intestine
 Out of these hepatic
and intestinal surfaces
are covered by
peritoneum.

24.  Lateral border is related to right lobe of liver
and hepatic flexure of colon.
 Posterior surface is related to 12th rib.

25.  Other relation of left
kidney-
 Anterior surface-
1. Suprarenal gland
2. Spleen
3. Stomach
4. Pancreas
5. Splenic vessels
6. Splenic flexure and
descending colon
7. Jejunum
 Out of these gastric,
splenic and jejunal
surfaces are covered
by peritoneum

26.  Lateral border is related to spleen and
descending colon.
 Posterior surface is related to 11th and 12th
rib.

27.  It consist of inner
medulla and outer
cortex.
RENAL MEDULLA-
 It consist of pale,
striated and 6-14 conical
renal pyramids.
 The base of pyramid is
directed to the
periphery and apex
converge to renal sinus
which project into wall
of renal sinus as renal
papilla.
 Each papilla is
perforated by 16 to 20
ducts of Bellini and is
received by minor calyx.

28.  One minor calyx receives 1 to 3 renal papilla.
 One pyramid capped with adjoining cortex
known as lobe of kidney.

29. RENAL CORTEX-
 It is subcapsular.
 It is arched over base of pyramids and this part is
called cortical arches or cortical lobules
 The part which extends between them towards
renal sinus is called renal columns.

30. RENAL SINUS-
 It is a cavity within kidney and communicates outside
throught hilum.
 Contents-
1. Renal blood vessels, lymph vessels and nerves.
2. Perinephric fat
3. Excretory apparatus of kidney including major and minor
calyx and pelvis of ureter.

31. MINOR CALYX-
 They are 7-13 in number and their dilated outer end present
cup shaped depression to receive renal papillae.
 In ureteric obstruction, the outer ends are dilated to form
club like elevations.
MAJOR CALYX-
They are 2-3 in number and are formed by the union of minor
calyx.

32. PELVIS OF URETER-
 It is funnel shaped dilatation and is formed
by union of major calyx.
 It passes downwards and medially through
the hilum and is continuous with ureter.

33.  Renal artery one on each side.
 It divides into anterior and posterior
divisions.
 Further branching give rise to segmental
arteries which supply following 5 segments-
1. Apical
2. Upper
3. Middle
4. Lower
5. Posterior

34.  Each segmental
arteries divide
into lobar
arteries, usually
one for each
pyramid.
 Each lobar artery
divides into 2-3
interlobar
arteries.
 At
corticomedullary
junction, it divide
into arcuate
arteries which
arch over bases
of pyramid at
right angle to
interlobar artery.

35.  It give interlobular arteries which run into cortical
substance at right angle to arcuate artery.
 Afferent glomerular arterioles are derived mostly
as side branches from interlobular arteries.

36.  Efferent glomerular arterioles divide to form
peritubular capillary plexus around proximal and
distal convoluted tubule.

37.  Arterial supply of
medulla is derived
mostly from efferent
arterioles of
juxtamedullary
glomeruli and partly
number of aglomerular
arterioles.
 Each arteriole dip into
renal pyramid, breaks
up into 12-25
descending vasa recta
which run into outer
part of medulla.
 At venous end the
plexus give rise to
ascending vasa recta
which return blood to
interlobular or arcuate
veins.

38. Venous end of peritubular capillary plexus
interlobular veins arcuate veins
interlobar vein join to form renal vein
IVC

39.  Lymphatics drain into lateral aortic nodes
located at level of origin of renal arteries
(L2).

40.  Supplied by renal plexus.
 It contains sympathetic (T10-T11) fibers and
is supplied by lesser splancnic nerve.
 Parasympathetic is derived from vagus.

41.  The angle between
lower border of 12th
rib and outer border
of erector spinae is
known as renal angle.
It overlies lower part
of kidney. Tenderness
in kidney can be
elicited by applying
pressure over this
angle with thumb.
 Kidney is palpated
bimanually by placing
one hand behind
flank. When enlarged,
lower pole of kidney
becomes palpable on
deep inspiration.

42. HORSE-SHOE KIDNEY- lower poles of both kidneys
are united by an isthmus. Aorta and IVC lie
behind it and ureter pass in front of it.

43. FLOATING KIDNEY- kidney is suspended from
posterior abdominal wall by a fold of
peritoneum. In such condition upper pole may
be tilted downwards producing twisting of renal
vessels and pelvis of ureter. This is associated
with anuria and severe pain in loin region. This
phenomenon is known as DIETL’S CRISIS.

44.  Polycystic kidney-
sometimes the
secreting and
collecting tubules
fail to negotiate and
kidney is riddled with
numerous cyst. This
condition is usally
bilateral.
 Accessory renal
artery- it is observed
in 30% individuals.
Sometimes the lower
pole of kidney is
supplied by accessory
artery which arises
from aorta. Artery
may cause
obstruction of flow
of urine producing
hydronephrosis.

45.  Since branches of renal arteries are end arteries,
anastomoses must be made to all arteries of the
donar kidney in renal transplant operations.
 Large stones lodging in the renal calyces may be
fragmented into smaller pieces by extra-
corporeal application of shock-wave therapy.
This method is known as LITHOTRIPSY.
 A kidney with stenosis of renal artery produces
systemic hypertension due to overabundance of
angiotensin. In this condition, surgical
anastomosis of splenic to the renal artery is
made beyond the area of stenosis.

46.  The common diseases of kidney are
nephritis, pyelonephritis, tuberculosis of
kidney, renal stones and tumours.
 Common manifestations of kidney diseases
are renal oedema and hypertension. Raised
blood urea indicates suppressed kidney
function and renal failure.
 In cases of chronic renal failure dialysis
needs to be done. It can be done as
peritoneal dialysis or haemodialysis.