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19
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TOPOGRAPHIC ANATOMY
OF THE LUMBAR REGION AND OF THE
RETROPERITONEAL SPACE
Operative surgery of the kidneys and ureters
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Lumbar region is posterior abdominal wall. The borders of the lumbar region are
composed of: superiorly – the twelfth rib, inferiorly – the iliac crest, medially –
spinous processes of the lumber vertebrae, laterally – midaxillary line.
Layers.
1. Skin.
2. Subcutaneous fat.
3. Superficial fascia.
4. Fatty layer in the inferior region. It is the so-called lumbogluteal fatty pillow.
5. Proper fascia.
6. Thoracolumbar fascia is a deep fascia.
7. Muscle.
The muscles of the lumbar region are divided into two basic groups (parts): medial
and lateral.
The muscles of the medial part:
1. The erector spinae muscle.
The left and right portion of the muscles lie in a trough on either side of the vertebral
spines. The trough is limited anteriorly by transverse processes and in the thoracic region
by the portion of ribs medial to their angles. The remainder of the muscle is enclosed by
thoracolumbar fascia. The muscle is suppÂlied by muscular branches of the dorsal rami of
spinal nerves.
2. Quadratus lumborum muscles.
This flat muscle lies immediately laterally to the upper part of psoas major. It is
quadrilaterally-shaped muscle that lies alongside the vertebral column. It extends from the
lower border of the twelfth rib and the tips of the lumbar transverse processes to the
iliolumbar ligament which spans the gap between the fifth lumbar transverse process and
the iliac crest itself. The anterior and middle sheets of the thoracolumbar fascia encÂlose
the quadratus lumborum muscle. The anterior sheet of this fascia is thickened above to
form the lateral arcuate ligament and below to form the iliolumbar ligament.
3. Psoas major muscle.
The psoas major muscle lies in the paravertebral gutter at the side of the bodies of
the lumbar vertebrae from the twelfth thoracic to the fifth lumber vertebrae. The fibers run
downward and laterally and leave the abdomen to enter the thigh by pasÂsing behind the
inguinal ligament. The lateral border of the psoas muscle converges with the inguinal
ligament. These muscles share a common attachment to the lesser trochanter of the femur.
The psoas is enclosed in a fibrous sheath that is derived from the lumbar fascia. The
sheath is thickened above to form the medial arcuate ligament. These muscles are supplied
by the lumbar plexus.
The muscles of the lateral part lie in three layers.
The first layer is composed of the latissimus dorsi and the external oblique muscles.
Although the lumbar part of the thoracolumbar fascia is an integral part of the
posterior abdominal wall, it forms an imÂportant site of origin for muscles of the lateral
and abdominal walls.
1. Latissimus dorsi is a large flat muscle. It's origin exÂtends from the lower six
thoracic spines, the lumbar spines, the sacral spines and the iliac crest by means of the
thoracolumbar fascia to which it is attached. It is supplied by the thoracoÂdorsal nerve
from the posterior cord of the brachial plexus.
2. The external oblique muscle having an oblique, free posteÂrior border that
extends from the up of the twelfth rib to the midpoint of the iliac crest. The fleshy fibers
fan out downward and medially over the anterior abdominal wall.
Lumbar triangle Pti is formed by a free posterior border of the external oblique
muscle – laterally, and by a free border of the latissimus dorsi – medially and the iliac
crest – from below that is the foundation of the triangle.
The second layer is composed of the serratus posterior inÂferior muscle and
internal oblique muscle.
The serratus posterior inferior is a thin flat muscle that arises from the upper lumbar
and lower thoracic spines. It's fiÂbers pass upward and laterally and are inserted to the
lower ribs.
The internal oblique muscle lies deeper than the external oblique one. It arises form
the thoracolumbar fascia, the anteÂrior two-thirds of the inguinal ligament. It forms the
floor of the lumbar triangle and has a triangle between it and serratus posterior inferior.
This is the "superior lumber triangle" LesÂgaft-Grunfeld.
This triangle is formed by serratus posterior inferior suÂperiorly, internal oblique
muscle inferiorly and by the erector spinal muscle - medially. The floor of this triangle is
formed by aponeurosis transversus abdominis muscle.
The third layer is composed of the transversus abdominis muscle. It lies deep to
the internal oblique, and it's fibers run horizontally forward. It arises form the deep surface
of the costal margin, the thoracolumbar fascia, the anterior two-thirds of the medial margin
of the iliac crest and the outer half of the inguinal ligament.
Subcostal nerve, artery and vein pierce posterior aponeuroÂsis of the transversus
abdominis muscle in triangle LesÂgaft-Grunfeld and continue anteriorly between internal
oblique and transversus abdominis muscle.
Lumbar triangle Pti and superior lumbar triangle LesÂgaft-Grunfeld are weak
points of the lumbar region where there can be phlegmons from the retroperitoneal bat
and seldom lumbar hernia.
The retroperitoneal space is located between anteriorly – parietal peritoneum of
the posterior abdominal wall and posteriÂorly – intra-abdominal fascia or transversalis
fascia.
Beneath the muscles of the medial and lateral parts of the posterior abdominal wall
lies a thin layer of transversalis fasÂcia, which covers the deep surfaces of transversus
abdominis quÂadratus lumborum and psoas major muscles. This fascia is called according
to the name of the muscle, which it covers. For exampÂle, psoas fascia, quadratus fascia,
transversal fascia are parts of the intra-abdominal fascia.
The retroperitoneal fat lies in three layers. Beneath the transversal fascia, counting
from the back frontward, there is the first layer of the retroperitoneal fat, which is called
proper retroperitoneal. It is immediate continuation of the extraperitoneal fat. The walls
of this fat layer are composed of: anteriorly – retroperitoneal fascia and renal fascia, it's
posterior layer; posteriorly – transversalis fascia; superiorly – diaphragm; inferiorly
– fat layer becomes pelvis fat.
The ways of pus spreading from retroperitoneal fat are the following:
1. Upwards pus can reach the diaphragm, there is a wear poÂint point of the
diaphragm, called lumbar-costal triangle BohdaÂleck and where pus can into thoracic
cavity.
2. Pus can pass through triangle Pti to lumbar region.
3. Pus can pass trough triangle Lesgaft-Grunfeld to the lumbar region under the
latissimus dorsi muscle.
4. Downwards: pus can get into the pelvic fat.
5. Forward: pus can get into the extraperitoneal fat of preperitoneal fat as it is
sometimes called.
In front of proper retroperitoneal fat there is retroperiÂtoneal fascia. It arises from
the point of the passage of parieÂtal peritoneum from the lateral abdominal wall to the
posterior abdominal wall and reaches the lateral border of the kidney. Here it divides into
two sheets or layers of the renal fascia anteriÂor and posterior. The renal fascia surround
the perirenal fat and encloses the kidneys. Anterior layer (sheet) encloses the suprarenal
glands. Below of the kidneys retroperitoneal fascia surrounds parauretric fat and encloses
the ureters.
The second layer of the retroperitoneal fat is composed of perirenal fat (pararenal)
and parauretric fat. They are closed fat spaces (layer) posterior layer of the renal fascia, is
conÂnected in the left aorta and in the right with inferior vena cava.
Anterior of anterior layer of the renal fascia there is the third layer of the
retroperitoneal fat, the so-called pericolic fat. The walls of this layer are composed of:
anteriorly - pariÂetal peritoneum of the posterior abdominal wall and retrocolic fascia
Toldi; posterior - retroperitoneal fascia and anterior layer of the renal fascia; superiorly transvers mesocolon; inÂferiorly in the left - cecum, in the right sigmoid mesocolon.
The retrocolic fascia Toldi arises (begins) from the point of the passage of parietal
peritoneum from the posterior wall to the ascending colon on the right and to the
descending colon on the left. It covers posterior walls of the ascending colon and the
descending colon.
Pus can get from the right to the left and vica venca in the pericolic fat. Let's take
down this material in the form of a table.
Fascia of the retroperitoneal
Fat layers of the retroperitoneal
Space
space
1.     fascia endoabdominal: 1. proper retroperitoneal fat
transverse fascia, psoas fascia,
quadratus fascia
2. retroperitoneal fascia  anterior 2. peritoneal fat, parauretric fat.
layer and posterior layer of the renal
fascia
3.     retrocolic fascia Toldi
3. pericolic fat.
Now let's take down layers of the retroperitoneal space in succession (sequence)
from the back frontward in the form a scheme.
Layers of the retroperitoneal space.
Medial part
Lateral part
Â
Endoabdominal fascia

quadratus fascia and psoas
transverse fascia

fascia

Proper retroperitoneal fat

Retroperitoneal fascia and posterior layer of the renal fascia

Perirenal fat, paraureteric fat

Kidney and ureter

Anterior layer of the renal fascia

Pericolic fat

Retrocolic fascia and parietal peritoneum of the posterior abdominal wall
Â
The retroperitoneal space contains organs, blood vessels, Lymph vessels and nerves.
The organs of the retroperitoneal spaÂce are: kidney, ureters, suprarenal glands, pancreas,
posterior walls of the ascending colon and descending colon, descending, horizontal and
ascending parts of the duodenum.
The vessels of the retroperitoneal space are: the abdominal aorta and it's branches,
the inferior vena cava and it's brancÂhes.
The nerves of the retroperitoneal space are: the sympatheÂtic trunks, aortic plexuses
and lumbar plexus and it's branches.
Lymph vessels of the retroperitoneal space are: the thoraÂcic duct, cisterna chyli
the intestinal trunk, the right and left lumbar trunks and lymph nodes.
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The topography of the kidneys
The kidneys are bean-shaped organs and are situated on either side of the vertebral
column in the lumbar region from the XI-XII thoracic vertebra to the II-III lumbar vertebra.
The right kidney lies slightly lower than the left kidney due to the bulk of the right
lobe of the liver. The kidney is composed of two poles - superior and inferior; two borders
- laÂteral convex and medial concave; two surfaces - anterior and posterior. The exact
position of the kidneys varies with respiÂration and the position of the body. Verify, that
the kidneys are not rigidly fixed to the posterior abdominal wall. In fact, in the living
subject, they move slightly up and down during respiration. A posterior surface faces
posteromedially and an anterior surface faces anterolaterally. A convex border faces
outward and a concave border inward. It is important to remember about their oblique
position, when radiographs are interpreted.
On the medial concave border of each kidney there is a verÂtical slit wich is called
the hilus. The hilus transmits from the front backward the following vessels and organs:
the renal vein, two branches of the renal artery, the renal pelvic and ureter and third branch
of the renal artery. Lymph vessels and sympathetic fibers also pass through the hilus.
Each kidney is convered by a fibrous capsule, which is cloÂsely applied to the
cortex and which in health may be stripped off easily. Each kidney and suprarenal gland is
surrounded by adipose tissue called perirenal fat. This is turn enclosed by the anterior and
posterior layers of the renal fascia. These laÂyers fuse above and lateral to the kidney.
Below they remain seÂparate around the ureter and blend with adjacent retroperitoneal
tissue. Some connection between these layers probably exists at the medial margin of the
kidney as fluid effusion within the fascia do not usually extend across the midline.
In some regions the kidney are covered by parietal peritoÂneum of the posterior
abdominal wall. This means that they are separated by this layer and the peritoneal cavity
from related structures which them selves will be covered by visceral peritoÂneum. In
other regions the relationship is to retroperitoneal structures which lift the peritoneum of
the kidney. With this in mind compare the anterior relations of each kidney and note that:
1. The medial aspect of both upper poles is directly relaÂted to a suprarenal gland.
2. The hilar region of the left kidney is directly related to the pancreas and the right
to the duodenum.
3. A substantial part of the lower pole of the right kidney is directly related to the
right colic flexire and similarly a lesser part of the left to the left colic flexure.
4. The left lower pole is covered with peritoneum and a siÂmilar but smaller area is
present over the right. These areas will be in contact with overlying small intestine.
5. The remainder of both kidney is also covered by peritoÂneum and related to the
overlying liver on the right and to the stomach and spleen on the left.
Except for the slight difference in levels, the posterior relations of the kidneys to the
diaphragm, the muscles of the posterior abdominal walls and the subcostal, iliohypogastric,
and ilioinguinal nerves are similar on both sides.
The subcostal, iliohypogastric and ilioinguinal nerves run downward and laterally.
It should, however, be remembered that costodiaphragmatic recess of the pleura
extends below the level of the twelfth rib, and that it may be accidentally apened during a
posterior approach to the kidney. The perirenal fat, renal fascia, muscles of the posterior
abdominal wall, vessels of the kidney ligaments and intra-abdominal pressure support the
kidneys and hold them in position on the posterior abdominal wall, but the perirenal fat or
adipose capsule plays the main role. Parietal peritoneum getting from adjacent organs to
kidneys from the ligaments. The ligaments of kidneys are composed of: hepatorenal
ligament, duoÂdenorenal ligament and lienorenal ligament.
We should also consider the pedicle of the kidney. It conÂsists of the vein, artery
and ureter or renal pelvis (from befoÂre backwards) the sympathetic nerves and the lymph
vessels. The renal artery often has two main branches. Sometimes accessory or aberrant
arteries enter the kidney above or below the hilum and may pass behind or in front of the
ureter. The arterial distriÂbution in the kidney is of surgical importance. Usually, the reÂnal artery divides into an anterior and posterior halves of the kidney. There are no
anastomoses. Thus, there are no large vesÂsels in the longitudinal plane of the kidney.
Hence, surgical procedures along this plane (nephrotomy) offer the advantage of
minimal hemorrhage. It is line of the naÂtural divisibility of the kidney. It is drawn one
centimetre backward from the lateral convex border. Blood returns from the kidneys to the
inferior vena cava through the large renal veins which run medially and anterior to the renal
arteries. As the inferior vena cava lies on the right hand side of the posterior abdominal
wall the right renal vein is short. Therefore it is more difficult to deal with it at operation
than with the left one and it is more likely to be invaded by a renal cell carcinoÂma. The
longer...
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