The abdomen is the region between the thorax and pelvis bounded superiorly by the diaphragm and inferiorly by the pelvis. It contains most of the digestive organs and some reproductive organs. The abdominal walls consist of skin, superficial fascia, muscles, and peritoneum. The abdomen can be divided into quadrants or nine regions to describe organ locations. The inguinal canal transmits structures between the abdomen and lower limbs and is the site of inguinal hernias.

1. The
Abdomen

2. Abdomen
• The abdomen is the part of the
trunk between the thorax and
the pelvis.
• It is a flexible, dynamic container,
housing most of the organs of
the alimentary system and part
of the urogenital system.
The abdomen consists of:
• abdominal walls
• abdominal cavity
• abdominal viscera

3. Anterior Abdominal Wall
Boundaries
• Superior:
• xiphoid process
• costal cartilages of the 7th-10th ribs
• Inferior:
• iliac crest
• inguinal fold
• pubic symphysis
• Lateral:
• posterior axillary line

4. Surface landmarks and regions of the
anterior abdominal wall
Topographical divisions of the abdomen are used to
describe the location of abdominal organs and the
pain associated with abdominal problems.
The two schemes most often used are:
1.A four-quadrant pattern
2.A nine-region organizational description.

5. Four-quadrant pattern
• Transverse Transumbilical
plane, passing through the
umbilicus (and the
intervertebral [IV] disc between
the L3 and L4 vertebrae)
• Vertical median plane passing
longitudinally through the
body, dividing it into right and
left halves to form four
quadrants-the right upper, left
upper, right lower, and left
lower quadrants

6. Using abdominal quadrants to locate
major viscera
• Liver and gallbladder
are in the right upper
quadrant.
• Stomach and spleen are
in the left upper
quadrant
• Cecum and appendix are
in the right lower
quadrant
• Descending colon and
sigmoid colon are in the
left lower quadrant.

7. Nine-region organizational pattern
• The nine regions are delineated by
four planes
two sagittal (vertical) and two transverse
(horizontal) planes.
1. Midclavicular planes that pass from the
midpoint of the clavicles (approximately 9 cm
from the midline) to the midinguinal points.
2. Subcostal plane is immediately inferior to the
costal margins, which places it at the lower
border of the costal cartilage of rib X and
passes posteriorly through the body of
vertebra LIII.
3. Intertubercular plane connects the tubercles
of the iliac crests, which are palpable
structures 5 cm posterior to the anterior
superior iliac spines, and passes through the
upper part of the body of vertebra LV.

8. The right and left midclavicular
lines subdivide it into:
Epigastrium:
• Epigastric region
• Right hypochondric region
• Left hypochondric region
Mesogastrium:
• Umbilical region
• Regio lateralis dex.
• Regio lateralis sin.
Hypogastrium:
• Pubic region
• Right inguinal region
• Left inguinal region

9. LAYERS of ABDOMINAL WALL
1- Skin
2- Subcutaneous tissue

10. 3. Superficial fascia
• Below the umbilicus,
it forms two layers: a
superficial fatty layer
and a deeper
membranous layer.

11. Superficial fatty layer of superficial fascia
(Camper's fascia)
• Contains fat and varies in
thickness.
• It is continuous over the inguinal
ligament with the superficial
fascia of the thigh and with a
similar layer in the perineum.
• Continues over the penis and,
after losing its fat and fusing with
the deeper layer of superficial
fascia.
• Continues into the scrotum
where it forms a specialized
fascial layer containing smooth
muscle fibers (the dartos fascia)

12. Deeper membranous layer of superficial
fascia (Scarpa's fascia)
• Is thin and membranous, and
contains little or no fat.
• Inferiorly, it fuses with the
deep fascia of the thigh (the
fascia lata).
• It continues into the anterior
part of the perineum where
it is referred to as the
superficial perineal fascia
(Colles fascia).

13. 4.Muscles
There are five (bilaterally paired) in the
anterolateral abdominal wall:
three flat muscles -
• external oblique,
• internal oblique, and
•transversus abdominis
two vertical muscles –
• rectus abdominis and
• pyramidalis

14. 1- External Oblique m.

15. 2- Internal Oblique m.

16. 3- Transversus
abdominis m.

17. 4- Rectus Muscle

18. 5- Pyramidalis is a
small, insignificant
triangular muscle that
is absent in
approximately 20% of
people.

19. 5. Fascia Transversalis

20. 6. Peritoneum

22. Functions and actions of anterolateral
abdominal muscles
•Move the trunk and help to maintain posture
(resisting lumbar lordosis).
• The rectus abdominis is a powerful flexor
•Support the abdominal viscera and protect them
from most injuries.
•Compress the abdominal contents to maintain or
increase the intraabdominal pressure
•Produce the force required for defecation (discharge
of feces), micturition (urination), vomiting, and
parturition (childbirth).

23. Rectus sheath
• The rectus abdominis
and pyramidalis
muscles are enclosed in
an aponeurotic
tendinous sheath (the
rectus sheath) formed
by a unique layering of
the aponeuroses of the
external and internal
oblique, and
transversus abdominis
muscles

24. Organization of the rectus sheath
A. Transverse section
through the upper ¾ of
the rectus sheath
B. Transverse section
through the lower ¼ of
the rectus sheath

25. Upper ¾ of the rectus sheath
The anterior wall of the rectus sheath consists of
• the aponeurosis of the external oblique
• & half of the aponeurosis of the internal oblique

26. Upper ¾ of the rectus sheath Cont’d
The posterior wall of the rectus sheath consists of
• The other half of the aponeurosis of the internal oblique
• & aponeurosis of the transversus abdominis

27. Lower 1/4 of the rectus sheath
The anterior wall of the sheath consists of the
aponeuroses of the external oblique, internal oblique,
and transversus abdominis m.
There is no posterior wall at the lower ¼ of the rectus
sheath

28. Arterial supply and venous drainage
Superficially:
• The superior part of the
wall is supplied by branches
from the musculophrenic
artery, a terminal branch of
the internal thoracic artery.
• The inferior part of the wall
is supplied by the medially
placed superficial epigastric
artery and the laterally
placed superficial
circumflex iliac artery, both
branches of the femoral
artery.

29. Arterial supply and venous drainage
At a deeper level:
• The superior part
of the wall is
supplied by the
superior epigastric
artery, a terminal
branch of the
internal thoracic
artery.
• The lateral part of
the wall is supplied
by branches of the
tenth and
eleventh
intercostal
arteries and the
subcostal artery.

30. Arterial supply and venous drainage
At a deeper level:
• The inferior part of
the wall is supplied
by the medially
placed inferior
epigastric artery
and the laterally
placed deep
circumflex iliac
artery, both
branches of the
external iliac artery.
The superior and inferior epigastric arteries both enter the
rectus sheath. They are posterior to the rectus abdominis
muscle throughout their course, and anastomose with each
other

31. Veins:
In the upper abdomen:
• Thoracoepigastric v.
In the lower abdomen:
• Superficial epigastric v.
• Superficial circumflex
iliac v.
• External pudendal v.
Around the umbilicus:
• Parumbilical veins
Deep veins:
• Intercostal vv.
• Superior epigastric v.
• Inferior epigastric

32. Lymphatic drainage
From the upper
abdominal half to:
• Axillary lymph nodes
From the lower abdominal
half to :
•Superficial inguinal
lymph nodes

33. Innervation
• Intercostal nn. Th7 –
Th11
• Subcostal n.Th12
•Branches of lumbal
plexus Th12 – L4:
- Iliohypogastric n.
- Ilioinguinal n.
- Genitofemoral n

34. INGUINAL CANAL
• Surgically an important canal because it is the site of
inguinal hernias
• obliquely located;tubelike
• 3-4cm. in length.
• Has two openings :
• Superficial inguinal ring
external oblique apon.
-medial
• Deep ingunal ring:
transversalis fascia
- Lateral

35. INGUINAL CANAL
• Anterior wall
• Post. Wall
• Superior wall
• inferior wall
4-6
cm

36. INGUINAL CANAL
Anterior wall
The anterior wall of the inguinal
canal is formed along its entire
length by the aponeurosis of
the external oblique muscle
Posterior wall
The posterior wall of the inguinal
canal is formed along its entire
length by the transversalis
fascia
Superior wall
The roof (superior wall) of the
inguinal canal is formed by the
arching fibers of the
transversus abdominis and
internal oblique muscles
Inferior wall
The floor (inferior wall) of the
inguinal canal is formed by the
medial one-half of the inguinal
ligament

37. Contents
• The contents of the inguinal canal are:
• images the spermatic cord in men,
• images the round ligament of the uterus, and
• images genital branch of the genitofemoral nerve in
women.
• These structures enter the inguinal canal through the
deep inguinal ring and exit it through the superficial
inguinal ring.

38. Boundaries of abdomen
• Superiorly: The inferior
thoracic aperture forms the
superior opening to the
abdomen, and is closed by the
diaphragm.
• Inferiorly: the deep abdominal
wall is continuous with the
pelvic wall at the pelvic inlet.

39. Boundaries of abdomen
• Anteriorly: anteriorly, a
segmented muscle (the
rectus abdominis) on each
side spans the distance
between the inferior
thoracic wall and the pelvis
• Laterally: lateral parts of the
abdominal wall are
predominantly formed by
three layers of muscles
• Posteriorly: vertebral
column, the quadratus
lumborum, psoas major,
and iliacus muscles