The posterior abdominal region contains several important structures. The lumbar vertebrae and sacrum form the bony framework in the midline. The psoas major and minor muscles cover the sides of the lumbar vertebrae and attach to the femur. The quadratus lumborum muscles fill the space between rib 12 and the iliac crest laterally. The suprarenal glands are located superior to each kidney within the perinephric fat. Major blood vessels include the abdominal aorta, which bifurcates into the common iliac arteries at L4, and the inferior vena cava, which returns blood to the heart. Nerves in the region include the sympathetic trunks and splanchnic

1. Abdomen Part 4
(POSTERIOR ABDOMINAL
REGION)
Themba Hospital FCOG(SA) Part 1 Tutorials
By Dr N.E Manana

2. • 4.140

3. Bones
Lumbar vertebrae and the sacrum
• Projecting into the midline of the posterior abdominal area are the
bodies of the five lumbar vertebrae
• The prominence of these structures in this region is due to the
secondary curvature (a forward convexity)
• The lumbar vertebrae can be distinguished from cervical and thoracic
vertebrae because of their size

4. Bones
Ribs
• Superiorly, ribs XI and XII complete the bony framework of the
posterior abdominal wall
• These ribs are unique in that they do not articulate with the sternum
or other ribs
• They have a single articular facets on their heads, and they do not
have necks or tubercles
• Rib XI is posterior to the superior part of the left kidney, and rib XII is
posterior to the superior part of both kidneys

5. • 4.141

6. Muscles
• Muscles forming the medial, lateral, inferior, and superior boundaries
of the posterior abdominal region
• Medially are the psoas major and minor muscles, laterally is the
quadratus lumborum muscle, inferiorly is the iliacus muscle, and
superiorly is the diaphragm
Psoas major and minor
• Cover the anterolateral surface of the bodies of the lumbar vertebrae,
• Each of these muscles arises from the bodies of vertebra TXII and all
five lumbar vertebrae

7. Muscles
• Associated with the psoas major muscle is the psoas minor muscle,
which is sometimes absent
• Lying on the surface of the psoas major, this slender muscle arises
from vertebrae TXII and LI and the intervening intervertebral disc
• Its long tendon inserts into the pectineal line of the pelvic brim and
the iliopubic eminence.
Quadratus lumborum
• Fill the space between rib XII and the iliac crest
• They are overlapped medially by the psoas major muscles
• Along their lateral borders are the transversus abdominis muscles

8. • 4.142

9. Muscles
• Each quadratus lumborum muscle arises from the transverse process
of vertebra LV
• The muscle attaches superiorly to the transverse process of the first
four lumbar vertebrae and the inferior border of rib XII.
Iliacus
• Inferiorly, an iliacus muscle fills the iliac fossa on each side
• The muscle passes inferiorly, joins with the psoas major muscle, and
attaches to the lesser trochanter of the femur
• As they pass into the thigh, these combined muscles are referred to
as the iliopsoas muscle

10. • Table 4.2

11. • 4.143

12. Viscera
Suprarenal glands
• Associated with the superior pole of each kidney
• They consist of an outer cortex and an inner medulla.
• The right gland is shaped like a pyramid, whereas the left gland is
semilunar in shape and the larger of the two.
• They are surrounded by the perinephric fat
• Enclosed in the renal fascia, though a thin septum separates each
gland from its associated kidney

13. • 4.163

14. Vasculature
Abdominal aorta
• Begins at the aortic hiatus of the diaphragm as a midline structure at
approximately the lower level of vertebra TXII
• At vertebra LIV it divides into the right and left common iliac arteries.
• This bifurcation can be visualized on the anterior abdominal wall as a
point approximately 2.5 cm below the umbilicus or even with a line
extending between the highest points of the iliac crest.
• As the abdominal aorta passes through the posterior abdominal
region, the prevertebral plexus of nerves and ganglia covers its
anterior surface

15. • 4.164

16. • Table 4.3

17. Inferior vena cava
• Returns blood from all structures below the diaphragm to the right atrium
of the heart
• Formed when the two common iliac veins come together at the level of
vertebra LV, just to the right of midline
• It ascends through the posterior abdominal region anterior to the vertebral
column immediately to the right of the abdominal aorta
• Leaves the abdomen by piercing the central tendon of the diaphragm at
the level of vertebra TVIII
• Tributaries include the: 1.common iliac veins, 2. lumbar veins, 3. right
testicular or ovarian vein, 4. renal veins,5. right suprarenal vein, 6. inferior
phrenic veins, and 7. hepatic veins

18. • 4.166

19. • 4.167

20. • 4.168

21. Nervous system in the posterior abdominal
region
• Several important components of the nervous system are in the
posterior abdominal region.
• The sympathetic trunks and associated splanchnic nerves,
• The plexus of nerves and ganglia associated with the abdominal
aorta,
• And the lumbar plexus of nerves.

22. • 4.169

23. • 4.170

24. • 4.171

25. • Table 4.5

26. • 4.173

27. • Table 4.6

28. Thank you