The document provides detailed information about the posterior abdominal wall, diaphragm, abdominal aorta, inferior vena cava, and lumber plexus as presented by Dr. Mohamed Elfiky. It describes the origin, insertion, course, branches, and relations of these structures. Key points include that the diaphragm separates the thoracic and abdominal cavities and is innervated by the phrenic nerves. The abdominal aorta descends in front of the lumbar vertebrae and gives off various branches. The IVC forms from the common iliac veins and pierces the diaphragm to drain into the right atrium. The lumbar plexus emerges from the psoas major

1. Posterior abdominal wall , diaphragm ,
abdominal aorta , I.V.C and lumber
plexus
Dr. Mohamed Elfiky
Professor of anatomy and embryology

2. Diaphragm
Mohamed el fiky
• Nature & shape :
•- It is a large dome-shaped musculo-tendinous partition which
separates the
•thoracic cavity from the abdominal cavity.
•- Its upper surface is convex towards the thoracic cavity, while
its lower
•surface isconcave towards the abdominal cavity.
•- Its right side (Rt. cupola) bulges higher up than its left side
(Lt. cupola) due
•to the upward bulge of the underlying Rt. lobe of the liver.

3. Diaphragm
Origin : The peripheral part of the diaphragm takes origin from the
circumference of the outlet of the thorax. The origin is divided into 3
parts:
(1) Sternal Origin: by 2 slips from the back of the xiphoid process.
(2) Costal Origin: by slips from the inner surfaces of the lower 6 costal
cartilages of both sides.
(3) Vertebral Origin: by 2 muscular bands (Rt. & Lt. Crura ) and from 5 arcuate ligaments (one median , 2 medial & 2 lateral ):
(a) The Rt. Crus: arises from the bodies of the upper 3 lumbar vertebrae.
(b) The Lt. Crus: arises from the bodies of the upper 2 lumbar vertebrae.
(c) The median arcuate ligament : is a tendinous arch that connects
the 2 crura together.
(d) Medial arcuate ligament .: (Rt.& Lt.) : is a tendinous arch
that connects the crus with the tip of the transverse process of the
1st lumbar vertebra.
(e) lateral arcuate ligament . (Rt. & Lt.) : is a tendinous arch which connects the tip of the transverse process of the 1st
lumbar vertebra to the last rib.
Mohamed el fiky

4. • Insertion: the fibres of the stemal, costal & vertebral parts
converge to be inserted into a crescentic central tendon which is
more ant. than post. in position.
• Nerve supply:
1- The phrenic nerves (motor).
2- Branches from the lower 6 or 7 intercostal nerves: sensory to
the periphery of diaphragm.
Action: The diaphragm is the main muscle of inspiration. Its
contraction leads to its descent & increase in the vertical diameter
of the thoracic cavity.
Mohamed el fiky

5. Relations of the diaphragm:
A- Upper surface:
1.(1) Its central tendon is related to the pericardium & heart.
2.(2) Rt. cupola is related to Rt. pleura & base of Rt. lung.
3.(3) Lt. cupola is related to Lt. pleura & base of Lt. lung.
A- Lower surface:
(1) Rt. cupola is related to Rt. lobe of liver, Rt.Kidney & Rt,
suprarenal gland.
(2) Lt. cupola is related to Lt. Lobe of liver, fundus of stomach,
Lt. kidney & Lt. suprarenal gland.
Mohamed el fiky

6. Item Vena cava Oesophagus Aorta
Level T8 T10 T12
Site Central tendon Fleshy part of right crus
Behind median arcuate
ligament.
Contents
1- I.V.C.
2- Rt. Phrenic n.
3- Lymph
vessels
1. Oesophagus.
2. Rt. & Lt. vagi.
3. Oesophageal
branch of Lt. gastric vessels.
1.Aorta.
2. Thoracic duct.
3.Azygos vein.
The Major Openings of the diaphragm
Mohamed el fiky

7. 1. Splanchnic nerves: pierce the crura of the diaphragm.
2. Sympathetic trunks: pass behind the med. arcuate ligament.
3. Sup. epigastric a. : passes between the slip of sternal origin.
Minor structures passing through the diaphragm: (S,S,S)
Mohamed el fiky

8. Muscles Of Posterior Abdominal Wall
(1) PSOAS MAJOR MUSCLE
Origin : From:
(1) Sides of last thoracic & all lumbar vertebrae and the
intervening intervertebral discs.
(2) Lumbar transverse processes.
Course :
The lower part of the muscle leaves the abdomen behind the
lateral part of the inguinal ligament closely related to iliacus
muscle.
Insertion: together with iliacus, it forms the ilio-psoas tendon
that is inserted into the lesser trochanter of the femur.
Mohamed el fiky

9. Nerve Supply: anterior 1ry rami of lumbar nerves (L1,2,3,4)
Actions:
(1) Acting from its origin : it is the main flexor of the thigh.
(2) Acting from its insertion : it produces flexion of the trunk
over the thigh (e.g. when raising from recumbent position).
N.B. In fracture neck of femur, psoas major produces flexion &
lateral rotation of the thigh.
(1) PSOAS MAJOR MUSCLE
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10. Relations of psoas major
I- Its medial border is related to :
1. Sympathetic chain.
2. External iliac a.(along the pelvic brim).
3. I.V.C. overlapping the Rt. psoas major.
4. Aorta & para-aortic L.Ns anteromedial to the left major muscle.
5. Obturator nerve & lumo-sacral trunk emerge from its
medial side to the pelvis.
Mohamed el fiky

11. II- Posterior Relations:
1. Lumbar transverse processes
2. Medial border of quadratus lumborum muscle.
3. Capsule of hip joint (in the thigh).
N.B: Lumbar plexus is embedded in the post. part of the muscle.
III- Antero-lateral relations:
1. Medial arcuate ligament of the diaphragm.
2. Psoas minor muscle (if present).
3. Kidney, renal vessels & ureter.
4. Duodenum (2nd part infront of the Rt. muscle & 4th part (Lt. side)
5. Gonadal vessels (testicular or ovarian)
6. Genito-femoral nerve.
7. Terminal part of ileum & caecum infront of Rt. muscle.
(8) Terminal part of descending colon and sigmoid colon
(9) Inguinal ligament & femoral sheath in the thigh. Mohamed el fiky

12. IV- The lateral border: is related to:
Quadratus lumborum m. (above ) & iliacus m. (below). It
gives exit to the following nerves (from above downwards):
1. Ilio-hypagastric n.
2. Ilio-inguinal n.
3. Lat. cut. n. of the thigh.
4. Femoral n.
Mohamed el fiky

13. Origin: ilio-lumbar lig.& the adjoining 5 cm. of inner lip of iliac crest.
Insertion:
Into med. 1⁄2 of lower border of last rib.
Nerve Supply: the subcostal n.(T12) & ventral rami of L1,2,3.
Action :- lateral flexion of the vertebral column. - muscle of inspiration :
by fixing the last rib during the contraction of the diaphragm.
PSOAS MINOR MUSCLE
It is a small m. lying in front of psoas major ( in about 60% of people ).
Origin : bodies of T12 & L1 and the inter-vertebral disc in-between.
Insertion: by a long tendon into the pectineal line & ilio-pectineal
eminence .
Nerve Supply: ventral ramus of L1.
Action: weak flexor of the lumbar vertebral column.
QUADRATUS LUMBORUM M.
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14. Abdominal Aorta
Origin : At the aortic opening of the diaphragm as a
continuation of the descending thoracic aorta at the level
of lower border of T12 vertebra.
Termination : at the lower border of L4 vertebra slightly
to the left of the median plane by dividing into 2 common
iliac arteries.
Course : It descends in front of the bodies of the upper 4
lumbar vertebrae with a slight inclination to the left.
Mohamed el fiky

15. 1. Phrenic arteries:
Arise form the front of abd. aorta opposite upper bonder of L1.
They run upwards & forwards. The Rt. one passes behind the I.V.C.,
while the Lt. one passes behind the oesophagus & ramify on the under
surface of diaphragm.
2. Middle suprarenal as:
Arise from the front of aorta apposite lower border of L1.
They run laterally on the crura of the diaphragm (Rt. one passes behind
the I.V.C.) to supply the suprarenal gland.
Branches Of Abd. Aorta
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16. (3) Renal arteries:
Arise from the sides of abd. aorta appossite L2.
Each a. passes laterally in front of the corresponding crus of diaphragm.
The Rt. a. is longer & passes behind the I.V.C.
The Lt. a. is shorter & passes behind the Lt. renal vein.
(4) Gonadal (Testicular or Ovarian) arteries :
The Rt. Testicular a. descends on the post. abd. wall to reach the deep inguinal
ring.
(5) Median sacral a. : arises from the back of abd. aorta opposite L4 vertebra.
Branches Of Abd. Aorta
Mohamed el fiky

17. Single branches Paired branches
Upper border
L1
Lower border
Coeliac trunk
Superior mesenteric A.
Phrenic
Middle surarenal
L2 Renal
L3 Inferior mesenteric gonadal
L4 Median sacral ( from back) Common iliac
Branches Of Abd. Aorta
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18. Inferior Vena Cava
Beginning: at the lower border of L5 vertebra by the union of 2
common iliac veins slightly to the Rt. side of middle line.
Termination: It pierces the central tendon of diaphragm (opposite
T8) to end by opening into the post. inf. part of Rt. atrium at the
level of the Rt. 6th costal cartilage.
Course: from its origin, it ascends infront of the vertebral column
(on the Rt. side of abd. aorta & pierces the central tendon of
diaphragm (at T8, 1 inch to the Rt. side of median plane) to end in
the Rt. atrium.
Mohamed el fiky

19. 1. two common iliac veins.
2. twopairs of lumbar veins (3 rd lumbar Rt. & Lt.).
3. two renal veins (Rt. & Lt.) the Lt. vein is longer.
4. Rt. suprarenal v. & Rt. gonadal v.(Testicular or Ovarian).
5. Two phrenic veins from the inf. surface of the diaphragm.
6. twohepatic veins which are very shrot & open into I.V.C. as
it passes in the groove on the past. surface of Rt. lobe of the liver.
Tributaries of I.V.C.
Mohamed el fiky

20. Lumbar Plexus
- It is formed inside psoas major muscle from the anterior 1ry rami of
upper 4 lumbar nerves.
- Its branches emerge from the lateral and medial borders of the muscle
and from its anterior surface.
Branches of the plexus :
1- Ilio-hypogastric and ilio and inguinal nerves (L1).
2- Lateral cutaneous nerve of the thigh (L2,3) enters the thigh behind
the lateral end of the inguinal ligament.
3- Femoral nerve (L2,3,4): dorsal division runs downwards between
psoas major m. and iliacus m. Mohamed el fiky

21. 4- Obturator nerve (L2,3,4): ventral division emerges from the medial
border of psoas major m. and crosses the pelvic brim in front the of sacro-
iliac joint.
5- Lumbo-sacral trunk : takes part information of sacral plexus.
6- Genito-femoral nerve: (L1,2) emerges from anterior surface of psoas
major m. It divides into:
(a) Genital branch: supply the cremasteric muscle.
(b) Femoral branch: supply a small area of skin of the front of the thigh.
7- Accessory obturator nerve: If presents, it supplies the pectineus muscle
Lumbar Plexus
Mohamed el fiky