The anterior abdominal wall has 6 layers from superficial to deep: 1) skin, 2) superficial fascia, 3) deep fascia, 4) 3 muscle sheets (external oblique, internal oblique, transversus abdominis), 5) extraperitoneal fascia, and 6) parietal peritoneum. The 3 muscle sheets come together to form the rectus sheath surrounding the rectus abdominis muscle. These muscles functions include lateral flexion, rotation, trunk flexion, pelvic stabilization, respiration, forced expiration, and increasing intra-abdominal pressure for various functions like micturition. They are supplied by nerves from the lower thoracic and lumbar regions.

1. Structure of the Anterior
Abdominal Wall
Dr . Mohaned abu lehea

2. • The anterior abdominal wall is made up of :
1. Skin
2. Superficial fascia
3. Deep fascia
4. Muscles
5. Extraperitoneal fascia
6. Parietal peritoneum

4. 1. Skin
• The 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 the linea alba

6. Nerve Supply to Skin
• The cutaneous nerve supply to the anterior
abdominal wall is derived from the anterior
rami of the lower six thoracic and the first
lumbar nerves.

7. • 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.

9. Blood Supply of Skin
• The skin near the midline is supplied by
branches of the superior and the inferior
epigastric arteries.
• The skin of the flanks is supplied by branches
of the
1. Intercostal arteries
2. Lumbar arteries
3. Deep circumflex iliac arteries

11. • Veins
• The venous drainage passes above mainly into
the axillary vein via the lateral thoracic vein
&
• Below into the femoral vein via the superficial
epigastric and the great saphenous veins

13. 2. Superficial Fascia
• The superficial fascia is divided into:
1. Superficial fatty layer (fascia of Camper)
2. Deep membranous layer (Scarpa's fascia)

16. • The fatty layer is continuous with the
superficial fat over the rest of the body and
may be extremely thick [8 cm] or more in
obese patients.

17. • 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.

18. 3. Deep Fascia
• It lies immediately deep to the membranous
layer of superficial fascia.

19. 4. Muscles
• The muscles of the anterior abdominal wall
consist of three broad thin sheets.
• From exterior to interior they are the
1. External oblique
2. Internal oblique
3. Transversus abdominis

20. • On either side of the midline anteriorly is, in
addition, a wide vertical muscle, the rectus
abdominis.

22. • As the aponeuroses of the three sheets pass
forward, they enclose the rectus abdominis to
form the rectus sheath.

24. • The lower part of the rectus sheath might
contain a small muscle called the pyramidalis.

26. A. External Oblique
• Origen : 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.

28. • A triangular-shaped defect in the external
oblique aponeurosis lies immediately above
and medial to the pubic tubercle.
• This is known as the superficial inguinal ring

30. • The spermatic cord passes through this
opening and carries the external spermatic
fascia (or the external covering of the round
ligament of the uterus) from the margins of the
ring.

32. • 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.

34. 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.

37. C. Transversus
• 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.

39. D. Rectus Abdominis
• The rectus abdominis is a long strap muscle
that extends along the whole length of the
anterior abdominal wall.
• It is broader above and lies close to the
midline, being separated from its fellow by the
linea alba.

41. • The rectus abdominis muscle is divided into
distinct segments by three transverse
tendinous intersections:
1. One at the level of the xiphoid process,
2. One at the level of the umbilicus
3. One halfway between these two

43. • These intersections are strongly attached to the
anterior wall of the rectus sheath.

44. E. Pyramidalis
• The pyramidalis muscle is often absent.
• Origin : anterior surface of the pubis and is
• Insertion : linea alba
• It lies in front of the lower part of the rectus
abdominis.

46. Rectus Sheath

47. 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.

49. • 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.

50. Function of the Anterior Abdominal
Wall Muscles

51. • The oblique muscles laterally flex and rotate
the trunk.
• The rectus abdominis flexes the trunk and
stabilizes the pelvis, and
• The pyramidalis keeps the linea alba taut
during the process.

52. • 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.

53. • The muscles assist in the act of forced
expiration that occurs during coughing and
sneezing by pulling down the ribs and sternum.

54. • Their tone plays an important part in
supporting and protecting the abdominal
viscera.

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

56. Nerve Supply of Anterior Abdominal
Wall Muscles
• The oblique and transversus abdominis
muscles are supplied by the lower six thoracic
nerves and the iliohypogastric and ilioinguinal
nerves (L1).

57. • The rectus muscle is supplied by the lower six
thoracic nerves.

58. • The pyramidalis is supplied by the 12th
thoracic nerve.

59. Fascia Transversalis
• The fascia transversalis is a thin layer of fascia
that lines the transversus abdominis muscle.

60. 5. Extraperitoneal Fat
• The extraperitoneal fat is a thin layer of
connective tissue that contains a variable
amount of fat and lies between the fascia
transversalis and the parietal peritoneum.

62. 6. Parietal Peritoneum
• The walls of the abdomen are lined with
parietal peritoneum .
• This is a thin serous membrane and is
continuous below with the parietal peritoneum
lining the pelvis.

63. Thanks