abdominal wall anatomy lecture Prof. dr Saif Gabaisha faculty of medicine ibb university

1. Posterior abdominal wall and associated structures
Ass. Prof. Dr. Saif Ali Ahmed Ghabisha

2. • The posterior abdominal wall extends from the 12th rib above to the pelvic brim
below.
Posterior abdominal wall and associated structures

3. Bony part:
• In the median plane, it is made up of bodies,
intervertebral disc, and transverse processes
of the five lumbar vertebrae.
• Laterally it is divided into upper and lower
parts by the iliac crest.
• The part above the iliac crest is made of
inner surfaces of the 12th rib and the part
below the iliac crest is made of iliac fossa.
The posterior abdominal wall is constructed as:
Posterior abdominal wall and associated structures

4. Muscular part:
• Above the iliac crest, from medial to lateral sides,
it is made up of psoas major, quadratus lumborum,
and transversus abdominis muscles.
• Below the iliac crest on either side of the lumbar
vertebral column from medial to lateral sides, it is
made up of psoas major and iliacus muscles.
The posterior abdominal wall is constructed as:
Fasciae:
• The psoas major and iliacus muscles are covered
by fascia iliaca.
• The quadratus lumborum is enclosed between the
anterior and posterior layers of the thoracolumbar
fascia.
Posterior abdominal wall and associated structures

5. The structures in the posterior abdominal wall:
• Muscles and fasciae of the posterior abdominal wall.
• Great vessels of the abdomen (abdominal aorta and inferior vena cava).
• Azygos and hemiazygos veins.
• Lymph nodes and lymphatics of the posterior abdominal wall.
• Nerves of the posterior abdominal wall.
Posterior abdominal wall and associated structures

6. Muscles of the posterior abdominal wall
Three muscles:
• psoas major
• iliacus
• quadratus lumborum
on each side of the vertebral column form most of the posterior abdominal wall.
Posterior abdominal wall and associated structures

7. Psoas major
• The psoas major is a long fusiform muscle extending from the sides of lumbar
vertebrae to the lesser trochanter of the femur.
• It is enclosed in a fascial sheath called psoas sheath.
Origin: The muscle arises from 14 fleshy slips:
• Five slips from intervertebral discs between T12–L5 vertebrae.
• Five slips from anterior surfaces and lower borders of the transverse process of five
lumbar vertebrae.
• Four slips from tendinous arches along the sides of upper four lumbar vertebrae.
Insertion: Enters the anterior surface of the tip of the lesser trochanter of the femur.
Nerve supply: The nerve supply is by direct branches from ventral rami of L2, L3, L4 spinal
nerves.
Posterior abdominal wall and associated structures

8. Psoas major
Posterior abdominal wall and associated structures

9. It is formed by the psoas fascia.
The attachments of psoas fascia:
Above: It is thickened to form medial arcuate
ligament, which extends from the body of L1
vertebra to the tip of its transverse process.
Laterally: It blends with the anterior layer of the
thoracolumbar fascia.
Medially: It is attached to the bodies and
intervening intervertebral discs of lumbar
vertebrae and presents four tendinous arches.
Below: It fuses with the arcuate line of the
pelvis and the fascia covering the iliacus
muscle (iliac fascia).
Psoas sheath
Posterior abdominal wall and associated structures

10. • This muscle is present in about 50% individuals.
• When present, it runs downward in front of
psoas major.
• In form and shape, it resembles the plantaris
muscle of the leg and is confined to the
abdomen.
Origin: It arises from the side of the intervertebral
disc between T12 and L1 vertebrae and adjoining
parts of their bodies.
Insertion: From the site of origin, the muscle runs
in front of the psoas major and ends in a long flat
tendon, which is inserted into the iliopubic
eminence.
Nerve supply: It is by a branch of L1 spinal nerve.
Action: It is a weak flexor of the trunk.
Psoas minor
Posterior abdominal wall and associated structures

11. • It is a fan-shaped muscle and forms the
lateral component of the iliopsoas muscle.
• Origin: it arises from the upper two thirds
of the floor of iliac fossa, inner lip of iliac
crest and upper surface of the lateral part
of the sacrum.
• Insertion: the fibres converge on and fuse
with the lower part of the psoas major
laterally and inserted with it on the anterior
surface of lesser trochanter and an area
(2.5 cm long) below it.
• Nerve supply: it is by the femoral nerve.
• Actions: along with the psoas major, it
causes flexion of the thigh and the lumbar
part of the vertebral column.
Iliacus
Posterior abdominal wall and associated structures

12. Quadratus lumborum
It is a quadrilateral muscle which fills the medial half of the
gap between the 12th rib, the iliac crest, and the tips of
transverse processes of lumbar vertebrae.
The quadratus lumborum muscle is enclosed between the
anterior and middle layers of the thoraco-lumbar fascia.
Origin: it arises from:
Posterior one-third of the inner lip of the iliac crest and
iliolumbar ligament.
Lower two to four transverse processes of lumbar
vertebrae.
Insertion: it is inserted into the medial part of the anterior
surface of the 12th rib. It is also inserted into the upper
lumbar transverse processes, posterior to its slips of
origin.
Nerve supply: ventral rami of t12–l3/l4 lumbar spinal n..
Posterior abdominal wall and associated structures

13. Great vessels of the abdomen
The great vessels of the abdomen are abdominal aorta and inferior vena cava.
Posterior abdominal wall and associated structures

14. Abdominal aorta
• The abdominal aorta begins as the
continuation of descending thoracic aorta at
the aortic orifice of the diaphragm opposite
to the lower border of the T12 vertebra or
intervertebral disc between vertebrae T12
and L1.
• It descends vertically downward and slightly
to the left, in front of the vertebral column,
and terminates in front of the lower part of
the body of L4 vertebra (about 1.25 cm) to
the left of the median plane by dividing into
right and left common iliac arteries.
• Length: 10–11 cm, Width: 2 cm.
Posterior abdominal wall and associated structures

15. Relations
Posterior:
• Bodies of the upper four lumbar vertebrae
and intervening intervertebral discs.
• Anterior longitudinal ligament.
• Third and fourth left lumbar veins.
Anterior: From above downward:
• Pancreas and splenic vein.
• Left renal vein.
• Third part of the duodenum.
• Root of the mesentery.
• Coils of the small intestine separated by
parietal peritoneum.
Right side: Inferior vena cava.
Left side: Left sympathetic trunk.
Posterior abdominal wall and associated structures

16. Branches
• Three unpaired ventral branches to
the gut.
• Three paired lateral branches to three
paired glands (suprarenal glands,
kidneys, and gonads).
• Paired posterolateral branches to the
abdominal wall.
• The aorta also gives rise to paired
inferior phrenic artery, unpaired
median sacral artery, and two
terminal branches.
Abdominal aorta
Posterior abdominal wall and associated structures

17. Inferior vena cava (IVC)
• The IVC is the largest and widest vein of the body.
• It drains most of the blood from the body below
the diaphragm into the right atrium of the heart.
• The IVC is formed by the union of right and left
common iliac veins in front of the body of L5
vertebra, below the aortic bifurcation, and behind
the right common iliac artery.
• It ascends in front of the vertebral column on the
right side of the aorta.
• It reaches the groove on the posterior surface of
the liver between the right and caudate lobes, just
above the groove it pierces the central tendon of
the diaphragm at the level of T8 vertebra and
terminates by entering the right atrium of the
heart.
Posterior abdominal wall and associated structures

18. Anterior: From below upward:
• Root of the mesentery.
• Right testicular/ovarian artery.
• Third part of the duodenum.
• Head of the pancreas and bile duct.
• Portal vein (posterior to first of duodenum and in
the right free margin of lesser omentum).
• Posterior surface of the liver between the right and
• caudate lobes.
Posterior: From below upward:
• Right sympathetic chain and psoas major.
• Right renal artery.
• Right coeliac ganglion.
• Right suprarenal gland (medial part).
• Right middle suprarenal vein.
• Right inferior phrenic artery.
Inferior vena cava (IVC) Relations
Posterior abdominal wall and associated structures

19. • Three formative veins: two common iliac veins
and the median sacral vein. The latter may join
the left common iliac vein. Each common iliac
vein receives an iliolumbar vein.
• Three abdominal wall tributaries: inferior phrenic
vein and third and fourth lumbar veins. The first
and second lumbar veins end in the ascending
lumbar vein.
• Three lateral visceral tributaries: right suprarenal
vein, renal veins, and right testicular/ovarian
vein. The left suprarenal vein and left gonadal
veins drain into the left renal vein.
• Three anterior visceral tributaries: right, middle,
and left hepatic veins.
Inferior vena cava (IVC) Tributaries
Posterior abdominal wall and associated structures

20. Inferior vena cava (IVC) Tributaries
Posterior abdominal wall and associated structures

21. Lymphatics and lymph nodes of the posterior abdominal wall
Lymphatics
• The lymph vessels draining the posterior abdominal wall and most of the
abdominopelvic organs except part of the liver terminate in the cisterna chyli
and thoracic duct.
• The lymphatic stream is intercepted by a series of lymph node groups before
reaching the cisterna chyli and the thoracic duct.
Tributaries of cisterna chyli
• Right and left intestinal lymph trunks: from the preaortic lymph nodes, which
open in its middle. These trunks drain the lymph from the small intestine,
stomach, and liver.
• Right and left lumbar lymph trunks: from the paraaortic lymph nodes, which
open in it inferiorly.
• A pair of lymph vessels: from the lower intercostal lymph nodes, which open in
it superiorly.
Posterior abdominal wall and associated structures

22. Lymphatics and lymph nodes of the posterior abdominal wall
Posterior abdominal wall and associated structures

23. Lymph nodes
Lymphatics and lymph nodes of the posterior abdominal wall
External iliac nodes: these are 8–10 in number and lie
along the external iliac vessels.
Common iliac nodes: these are 4–6 in number and lie
along the common iliac vessels (lateral group) and
below the bifurcation of the aorta (medial group).
Aortic lymph nodes: they are situated along the
abdominal aorta and inferior vena cava, and are
arranged into two groups: pre-aortic and para-aortic.
Pre-aortic nodes: the nodes are located around the
Origin of ventral branches to the gut.
Para-aortic (lateral aortic) nodes: they are situated on
each side of the abdominal aorta, some nodes of this
group lie behind the aorta and called retroaortic nodes.
Posterior abdominal wall and associated structures

24. Lymphatics and lymph nodes of the posterior abdominal wall
Posterior abdominal wall and associated structures

25. Nerves of the posterior abdominal wall
The nerves of the posterior abdominal wall include subcostal nerve, ventral rami of lumbar
nerves, and lumbar sympathetic chains.
Posterior abdominal wall and associated structures

26. • It is the ventral ramus of the 12th
thoracic spinal nerve.
• It enters the abdomen behind the
lateral accurate ligament (lateral
lumbocostal arch) and runs
downward and laterally in front of the
quadratus lumborum beneath the
anterior layer of thoraco-lumbar
fascia.
Subcostal nerve
Posterior abdominal wall and associated structures

27. Lumbar plexus
Posterior abdominal wall and associated structures

28. Abdominal part of the autonomic nervous system
The abdominal part of the autonomic
nervous system:
• Lumbar sympathetic chains.
• Autonomic plexuses of the posterior
abdominal wall.
Posterior abdominal wall and associated structures

29. Lumbar sympathetic chain
• It is a ganglionated chain situated on
either side of the lumbar vertebrae.
• It commences deep to the medial arcuate
ligament of the diaphragm as the
continuation of the thoracic sympathetic
trunk.
• The chain enters the pelvis in front of the
ala of sacrum beneath the common iliac
vessels, where it continues as the sacral
sympathetic chain in front of the sacrum.
Branches
• White rami communicantes
• Gray rami communicantes
• Lumbar splanchnic nerves
Posterior abdominal wall and associated structures

30. Autonomic plexuses of the posterior abdominal wall
The preganglionic and postganglionic
sympathetic fibres, preganglionic
parasympathetic fibres, and visceral
afferent fibres form a plexus of nerves
around the abdominal aorta.
This plexus form two major plexuses:
• Coeliac
• Superior hypogastric plexuses.
Posterior abdominal wall and associated structures

31. Coeliac plexus (solar plexus)
• The coeliac plexus is located on the front of
the abdominal aorta around the coeliac
trunk and origin of the superior mesenteric
artery.
• The coeliac ganglia are two irregular
masses of nerve cells situated one on each
side of the origin of coeliac artery.
• Each ganglion is divided into a large upper
part and a lower part.
• The lower part is called aorticorenal
ganglion.
Posterior abdominal wall and associated structures

32. Coeliac plexus (solar plexus)
Posterior abdominal wall and associated structures

33. Branches
• Phrenic plexus
• Hepatic plexus
• Left gastric plexus
• Splenic plexus
• Suprarenal plexus
• Renal plexus
• Testicular plexus
• Ovarian plexus
• Superior mesenteric plexus
• Abdominal aortic plexus
(intermesenteric plexus)
• Inferior mesenteric plexus
Posterior abdominal wall and associated structures
Coeliac plexus (solar plexus)

34. • It lies in front of the bifurcation of the abdominal aorta and body of the fifth lumbar
vertebra between the two common iliac arteries.
• It is often referred to as presacral nerve but the plexus is never sufficiently condensed to
resemble a single nerve and moreover plexus is prelumbar rather than presacral in
position.
It is formed by the union of:
• Descending fibres of the aortic plexus.
• Third and fourth lumbar splanchnic nerves.
• Ascending filaments of inferior hypogastric plexus.
• These fibres supply the parts of gut derived from the hindgut.
Superior hypogastric plexus (presacral nerve)
Posterior abdominal wall and associated structures

35. Superior hypogastric plexus (presacral nerve)
Posterior abdominal wall and associated structures

36. Posterior abdominal wall and associated structures
Superior hypogastric plexus (presacral nerve)