The anterior abdominal wall is made up of skin, superficial fascia, deep fascia, muscles, extraperitoneal fascia, and parietal peritoneum. The major muscles are the external oblique, internal oblique, transversus abdominis, and rectus abdominis. Together, the muscles provide support, protection, and enable functions like micturition, defecation, vomiting, and parturition by increasing intra-abdominal pressure when contracting simultaneously with the diaphragm. The wall receives nerve innervation from the lower thoracic and upper lumbar nerves and has blood supply from branches of the internal mammary, external iliac, and descending thoracic arteries.

1. ANTERIOR
ABDOMINAL
WALL
D R . TA N YA R A S H I D
A N AT O M Y D E P T

2. STRUCTURE
MADE UP OF:
1. Skin
2. Superficial fascia
3. Deep fascia
4. Muscles
5. Extraperitoneal fascia
6. Parietal peritoneum

3. SKIN
• Skin is loosely attached to the underlying
structures except at the umbilicus, where it is
tethered to the scar tissue.
• The umbilicus is a scar representing the site of
attachment of the umbilical cord in the fetus, it
is situated in linea alba.
DERMATOME:
• The cutaneous nerve supply is derived from
the anterior rami of the lower six thoracic and
the first lumbar nerves.
• The dermatome of T7 is located over the
xiphoid process
• The dermatome of T10 includes the umbilicus
• That of L1 lies just above the inguinal ligament
and the symphysis pubis.

4. SUPERFICIAL FASCIA
• THE SUPERFICIAL FASCIA IS DIVIDED INTO:
– Superficial fatty layer (Camper’s fascia)
– Deep membranous layer (Scarpa’s fascia)
• The FATTY LAYER is continuous with the superficial
fat over the rest of the body and may be extremely
thick (8cm) or more in obese patients.
• The MEMBRANOUS LAYER is thin and fades out
laterally and above, where it becomes continuous
with the superficial fascia of the back and the thorax,
respectively.
DEEP FASCIA
• It lies immediately deep to the membranous
layer of superficial fascia

5. MUSCLES
• The muscles of anterior abdominal wall consists of
three broad thin sheets.
FROM EXTERIOR TO INTERIOR THEY ARE:
• External oblique
• Internal oblique
• Transversus abdominis
• On either side of the midline anteriorly is, in
addition, a wide vertical muscle, the RECTUS
ABDOMINUS.
• As the aponeuroses of the three sheets pass
forward, they enclose the rectus abdominis to form
the RECTUS SHEATH.
• The lower part of the rectus sheath might contain
a small muscle called the PYRAMIDALIS.

6. A. EXTERNAL OBLIQUE
• ORIGIN: The outer surfaces of the lower eight ribs and
fans out to be,
• INSERTION: The xiphoid process, the linea alba, the
pubic crest, the pubic tubercle, and the anterior half of
the iliac crest.
• Most of the fibers are inserted by means of a broad
aponeurosis
• A triangle shaped defect in the external oblique
aponeurosis lies immediately above and medial to the
pubic tubercle.
• This is known as the superficial inguinal ring.
• Between the anterior superior iliac spine and the pubic
tubercle, the lower border of the aponeurosis is folded
backward on itself, forming the INGUINAL LIGAMENT.

7. B. INTERNAL OBLIQUE
• ORIGIN:
Lumbar fascia, the anterior two thirds of the iliac
crest, and the lateral two thirds of the inguinal
ligament.
• INSERTION:
The lower borders of the lower three ribs, and
their costal cartilages, the xiphoid process, the
linea alba, and the symphysis pubis.

8. • EXTERNAL OBLIQUE MUSCLE FIBERS move downwards and
medially.
• INTERNAL OBLIQUE MUSCLE FIBERS move upwards and medially.

9. C. TRANSVERSUS ABDOMINUS
• ORIGIN:
The deep surface of the lower six costal
cartilages, the lumbar fascia, the anterior two
thirds of the iliac crest, and the lateral third of
the inguinal ligament.
• INSERTION:
The xiphoid process, the linea alba, and the
symphysis pubis.

10. D. RECTUS ABDOMINIS
• The rectus abdominis is a long strap
muscle that extends along the whole
length of the anterior abdominal wall.
• It is broaded above and lies close to the
midline, being separated from its fellow
by the linea alba.
• ORIGIN: pubic crest
• INSERTION: ribs (5th, 6th, 7th), xiphoid
process.

11. • The rectus abdominis muscle is
divided into distinct segments by
three transverse tendinous
intersections:
• 1. one at the level of xiphoid process
• 2. one at the level of the umbilicus
• 3. one halfway between these two
• These insertions are strongly attached
to the anterior wall of the rectus
sheath.

12. E. PYRAMIDALIS
• The pyramidalis muscle is often absent.
• ORIGIN: anterior surface of the pubis
• INSERTION: linea alba
• It lies infront of the lower part of the
rectus abdominis.

13. RECTUS SHEATH
• The rectus sheath is a long fibrous sheath
that encloses the rectus abdominis muscle
and pyramidalis muscle (if present)
• It is formed mainly by the aponeuroses of
the three lateral abdominal muscles.
• Between the costal margin and the level
of the anterior superior iliac spine, the
aponeurosis of the internal oblique splits
to enclose the rectus muscle; the external
oblique aponeurosis is directed in front of
the muscle, and the transversus
aponeurosis is directed behind the
muscle.

14. FUNCTIONS OF MUSCLES OF
ANTERIOR ABDOMINAL WALL
• OBLIQUE MUSCLE: laterally flex and route the trunk
• RECTUS ABDOMINIS: flexes the trunk and stabilizes the pelvis
• PYRAMIDALIS: keeps the linea alba taut during the process.
• The muscles of the anterior and lateral abdominal walls assist the diaphragm during
inspiration by relaxing as the diaphragm descends so that the abdominal viscera can
be accommodated.
• The muscles assist in the act of forces expiration that occurs during coughing and
sneezing by pulling down the ribs and sternum.
• Their tone plays an important part in supporting and protecting the abdominal viscera.

15. • By contracting simultaneously with the diaphragm, with the glottis of the
larynx closed, they increase the intra abdominal pressure and help in:
1. Micturation
2. Defecation
3. Vomiting
4. Parturition

16. NERVE SUPPLY OF MUSCLES OF
ANTERIOR ABDOMINAL WALL
• The oblique and transversus
abdominis muscles are supplied by
the lower six thoracic nerves and the
iliohypogastric and ilioinguinal nerves
(L1).
• The rectus muscle is supplied by the
lower six thoracic nerves.
• The pyramidalis is supplied by the 12th
thoracic nerve.

17. • FASCIA TRANSVERSALIS
• The fascia transversalis is a thin layer of fascia that lines the transversus
abdominis muscle.
• EXTRAPERITONEAL FAT:
• The extraperitoneal fat is a thin layer of connective tissue that contains a variable
amount of fat and lies between the fascia tranversalis and the parietal
peritoneum.
• PARIETAL PERITONEUM:
• The walls of abdomen are lined with parietal peritoneum
• This is a thin serous membrane and is continuous below with the parietal
peritoneum lining the pelvis.

18. BLOOD SUPPLY OF
ANTERIOR ABDOMINAL WALL
• ARTERIAL SUPPLY:
– Superior Epigastric artery: branch of Internal
Mammary artery.
– Inferior Epigastric artery: branch of External
Iliac artery
– Two Posterior Intercostal art.: Desc. Thor.
Aorta
– Four Lumbar arteries: Desc. Thor. Aorta
– Deep Circumflex iliac artery: branch of Ext.
Iliac artery
• VEINS:
• Above the umbilicus mainly into the axillary
vein via the lateral thoracic vein.
• Below the umbilicus into the femoral vein
through the superficial epigastric and the
great saphenous veins.

19. NERVE SUPPLY OF
ANTERIOR ABDOMINAL WALL
• Anterior rami of Lower 6 thoracic nerves
– T7 – T11 intercostal nerves
– T12: Subcostal nerve
• Anterior ramus of the 1st lumbar nerve
– Ilioinguinal nerve
– Iliohypogastric nerve
• Pass forward between the internal oblique
and transversus abdominis muscle.

20. LYMPH DRAINAGE OF
ANTERIOR ABDOMINAL WALL
SUPERFICIAL LYMPH VESSELS:
• Above umbilicus: anterior group of axillary
nodes
• Below umbilicus: superficial inguinal lymph
nodes
DEEP YMPH VESSELS:
Drain into the:
Internal thoracic, external iliac, posterior
mediastinal and para aortic (lumbar) nodes.

21. MULTIPLE CHOICE QUESTIONS
1. SUPERIOR EPIGASTRIC ARTERY IS A BRANCH OF:
• A. Descending thoracic aorta
• B. Abdominal aorta
• C. Internal thoracic artery
• D. External iliac artery

22. 2. MUSCLE FIBERS OF THE EXTERNAL OBLIQUE MOVE IN WHICH DIRECTION:
• A. upwards and medially
• B. upwards and laterally
• C. downwards and laterally
• D. downwards and medially

23. 3. INSERTION OF RECTUS ABDOMINIS:
• A. linea alba
• B. pubic crest
• C. xyphoid process
• D. anterosuperior iliac spine