Surgical anatomy of Anterior Abdominal wall

1. ANATOMY OF ANTERIOR ABDOMINAL WALL
AND PATHOPHYSIOLOGY OF HERNIA
PRESENTER-
DR AKSHAY SARRAF
1ST YEAR RESIDENT
DEPT. OF GENERAL SURGERY

2. OBJECTIVES
• Introduction
• Anatomy
- Muscular
- Vascular
- Nervous
• Hernia
• Pathophysiology

3. Introduction
• The abdominal wall is a complex structure
composed primarily of muscle, bone and fascia.
• Bounded by the xiphoid process and costal
margins, and by the upper parts of the pelvic
bones.
• There are nine layers to the abdominal wall:

4. Musculoskeletal anatomy
• Subcutaneous tissue-
• Consists of Camper (superficial adipose layer) and Scarpa fasciae(deeper,
denser layer of fibrous connective tissue).
• Camper continues over the penis and, after losing its fat continues into the
scrotum forming the dartos fascia.
• Scarpa’s fascia is thin and membranous, and contains little or no fat.
• In midline, it is firmly attached to the linea alba and the symphysis pubis and
in perineum makes superficial perineal fascia (Colles’ fascia) anteriorly.

6. • Muscles and Investing Fascias-
• There are five muscles in the anterolateral group of abdominal wall
muscles:
• Three flat muscles whose fibers begin posterolaterally, pass anteriorly, and
are replaced by an aponeurosis as the muscle continues toward the
midline—the external oblique, internal oblique, and transversus abdominis
muscles;
• Two vertical muscles, near the midline, which are enclosed within a
tendinous sheath formed by the aponeuroses of the flat muscles—the
rectus abdominis and pyramidalis muscles.

8. 1. The external oblique muscle and
Fascia
• Largest and thickest of the flat abdominal
wall muscle.
• Originate from the lower seven ribs
• Course in a superolateral to inferomedial
direction.
• Most posterior of the fibers run vertically
downward to insert into the anterior half
of the iliac crest.

9. • At the midclavicular line, give rise to a flat, strong aponeurosis that
passes anteriorly to the rectus sheath to insert medially into the
linea alba.
• The lower portion of the external oblique aponeurosis is rolled
posteriorly and superiorly on itself to form the inguinal or Poupart
ligament

10. • Surgical anatomy
• The inguinal ligament is the lower free edge of the external oblique
aponeurosis.
• the femoral artery, vein, and nerve and the iliacus, psoas major, and
pectineus muscles passes posterior to it.
• A femoral hernia passes posterior to the inguinal ligament, whereas
an inguinal hernia passes anterior and superior to it.
• The shelving edge of the inguinal ligament is used in various
repairs of inguinal hernia such as the Bassini and the Lichtenstein
repairs.

11. 2. Internal Oblique muscle
• Its fibers course inferolateral to
superomedially.
• originates from
- the iliopsoas fascia beneath the lateral
half of the inguinal ligament,
- from the anterior two thirds of the iliac
crest and
- lumbodorsal fascia
• The uppermost fibers insert into the
lower five ribs and their cartilages.

12. • Above the arcuate line contributes in anterior and posterior rectus
sheath formation whereas anterior rectus sheath below arcuate line.
• Lowermost fibers insert between the symphysis pubis and pubic
tubercle.
• Some of the lower muscle fascicles accompany the spermatic cord
into the scrotum as the cremasteric muscle.

13. 3. Transversus Abdominis Muscle
• smallest of the muscles of the
anterolateral abdominal wall.
• It arises from
- the lower six costal cartilages,
- spines of the lumbar vertebrae,
- iliac crest, and
- iliopsoas fascia beneath the lateral
third of the inguinal ligament.
• Inserts into Xiphoid process, linea
alba, pubic crest and pecten pubis
via conjoint tendon

14. • Courses transversely to give rise to a flat aponeurotic sheet.
• The sheet passes posterior to the rectus abdominis muscle above the
arcuate line and anterior to the muscle below it.
• Inferiormost fibers form the aponeurotic arch of the transversus
abdominis muscle which lies superior to Hesselbach triangle

15. • The transversalis fascia
• covers the deep surface of the
transversus abdominis muscle and
with its various extensions.
• Named for the muscles that it covers.
• Binds together the muscle and
aponeurotic fascicles into a continuous
layer
• Reinforces weak areas where the
aponeurotic fibers are sparse.

16. • Rectus Abdominis muscle
• Paired muscles that appear as long,
flat, triangular ribbons.
• Wider at origin on the anterior
surfaces of the 5th, 6th, and 7th costal
cartilages and the xiphoid process
than at pubic crest and pubic
symphysis.
• Composed of long parallel fascicles
interrupted by three to five tendinous
inscriptions.

17. • Held closely in apposition near the anterior midline by the linea
alba.
• Wider above the umbilicus than below.
• In addition to supporting the abdominal wall and protecting its
contents, their contraction flexes the vertebral column.
• Held in rectus sheath which consists of a band of dense,
crisscrossed fibers of the aponeuroses abdominal muscles that
extends from the xiphoid to the pubic symphysis.

18. • The Rectus Sheath
• Derived from the aponeuroses of the three flat abdominal muscles.

20. • Preperitoneal Space
• Lies between the transversalis fascia and
parietal peritoneum.
• Contains adipose and areolar tissue.
• Coursing through the preperitoneal space
are the following:
• Inferior epigastric artery and vein
• Medial umbilical ligaments, which are the
vestiges of the fetal umbilical arteries
• Median umbilical ligament, midline fibrous
urachus
• Falciform ligament of the liver, extending from
the umbilicus to the liver

21. • Important anatomic areas of interest, known as the triangle of doom,
the triangle of pain, and the circle of death.

22. • The Peritoneum
• The innermost layer of the abdominal wall.
• Consists of a thin layer of dense, irregular connective tissue
covered on its inner surface by a single layer of squamous
mesothelium.
• The surface area is 1.0 to 1.7 m2, approximately that of the total
body surface area.
• The peritoneal membrane is divided into parietal and visceral
components.

23. • Parietal peritoneum covers the anterior, lateral, and posterior
abdominal wall surfaces and the inferior surface of the diaphragm and
the pelvis.
• Visceral peritoneum covers most of the surface of the intraperitoneal
organs and the anterior aspect of the retroperitoneal organs.
• In males, the peritoneal cavity is sealed, whereas in females, it is open
to the exterior through the ostia of the fallopian tubes.

24. • The peritoneal cavity is subdivided by
11 ligaments and mesenteries into 9
interconnected compartments or spaces.
• These ligaments, mesenteries, and
peritoneal spaces direct the circulation
of fluid in the peritoneal cavity.

25. Vascular Anatomy
• The anterolateral abdominal wall receives
its arterial supply from
- Last six intercostal arteries,
- Last four lumbar arteries,
- Superior and inferior epigastric arteries, and
- Deep circumflex iliac arteries
• The trunks of the intercostal and lumbar
arteries, together with the intercostal,
iliohypogastric, and ilioinguinal nerves,
course between the transversus abdominis
and internal oblique muscles.

26. • The distal-most extensions of these vessels pierce the lateral
margins of the rectus sheath at various levels and communicate
with branches of the superior and inferior epigastric arteries.
• Superior Epigastric Artery
Terminal branch of the internal mammary artery.
Reaches the posterior surface of the rectus abdominis muscle through
the costoxiphoid space in the diaphragm.
Descends within the rectus sheath to anastomose with branches of the
inferior epigastric artery

27. • Inferior epigastic artery-
Derived from the external iliac artery just proximal to the inguinal
ligament.
courses through the preperitoneal areolar tissue to enter the lateral rectus
sheath at the semilunar line of Douglas.
• Deep Circumflex Iliac Artery-
From the lateral aspect of the external iliac artery near the origin of the
inferior epigastric artery.
Gives rise to an ascending branch that penetrates the abdominal wall
musculature just above the iliac crest, near the anterior superior iliac
spine.

28. • Venous drainage-
• The superficial veins above the
umbilicus empty into the superior vena
cava by way of the internal mammary,
intercostal, and long thoracic veins.
• Inferiorly, superficial epigastric,
circumflex iliac, and pudendal veins,
converge toward the saphenous
opening in the groin to enter the
saphenous vein and become a tributary
to the inferior vena cava.

29. • Numerous anastomoses between the infraumbilical and
supraumbilical venous systems provide collateral pathways
whereby venous return to the heart may bypass an obstruction of
the superior or inferior vena cava.
• The paraumbilical vein, provides communication between the veins
of the superficial abdominal wall and portal system.
• Visceral peritoneum is supplied by the splanchnic blood vessels.
• Parietal peritoneum is supplied by branches of the intercostal,
subcostal, lumbar, and iliac vessels.

30. • Lymphatic Drainage
• Follows a pattern similar to the venous drainage.
• Vessels arising from the supraumbilical region drain into the
axillary lymph nodes.
• Those arising from the infraumbilical region drain toward the
superficial inguinal lymph nodes.
• Lymphatic vessels from the liver course along the ligamentum teres
to the umbilicus to communicate with the lymphatics of the anterior
abdominal wall.

31. • Nervous supply and Innervation
• upper six thoracic nerves end near the
sternum as anterior cutaneous sensory
branches.
• T7 to T12 pass behind the costal
cartilages and lower ribs to enter a
plane between the internal oblique
muscle and the transversus
abdominis.

32. • While coursing medially they provide motor branches to the
abdominal wall musculature.
• Perforate the rectus sheath to provide sensory innervation to the
anterior abdominal wall.
• The anterior ramus of T10 supplies the skin at umbilicus and T12
innervated hypogastrium.

33. • Iliohypogastric Nerve-
• often arise with ilioinguinal from the anterior rami of the T12 and
L1.
• runs parallel to the T12 nerve to pierce the transversus abdominis
muscle near the iliac crest.
• Pierces the internal oblique to travel under the external oblique
fascia toward the external inguinal ring.
• Emerges at external inguinal ring to provide sensory innervation to
the hypogastrium and lower abdominal wall..

34. • Ilioinguinal Nerve
• courses parallel to the iliohypogastric nerve.
• Is closer to the inguinal ligament than the iliohypogastric nerve.
• Courses with the spermatic cord to emerge from the external
inguinal ring.
• Its terminal branches provides sensory innervation to the skin of
the inguinal region and scrotum or labium.

35. Pathophysiology of Hernia
• A hernia is an abnormal protrusion of an organ or tissue through an
opening in the layer that normally confnes it.
• may be congenital or acquired.
• Mostly acquired in adults but there is known hereditary association
that is not well understood.
• Because they ‘push’ from the inside to the outside, an abdominal
hernia takes with it all the coverings of the abdominal wall.

36. • Not all abdominal hernias have a peritoneal sac.
• most likely risk factor for inguinal hernia is weakness in the
abdominal wall musculature.
• Congenital hernias can be considered a developmental defect rather
than an acquired weakness
• disruptions of the abdominal wall as a result of injury.

37. • Many structures enter and leave the abdominal cavity, creating
weakness that can lead to hernia formation.
• examples of inherent areas of weakness include the deep inguinal ring,
oesophageal hiatus, the femoral canal and the umbilical cicatrix.
• Failure of normal development may lead to congenital hernias.
• most common is an indirect inguinal hernia arising through failure of
the processus vaginalis to close.

38. • Other examples of congenital herniation include Morgagni and
Bochdalek hernias of the diaphragm and some umbilical hernias.
• Weak areas of the abdominal wall may also arise from direct injury.
• A surgical scar has only 70% of the initial muscle strength.
• Smaller laparoscopic port-site incisions have a hernia rate of 1%.

39. • A normal abdominal wall has sufficient strength to resist high
abdominal pressure and prevent herniation of content.
• Straining brings the hernia to the attention of the patient, rather than
being the cause.
• Good evidence that hernia is a ‘collagen disease’ and is due to an
inherited imbalance in the types of collagen.
• Collagen disorders, such as ehlers–danlos syndrome, successful long-
term repair of a hernia can be very dificult.

40. • Hernia is more common in smokers as smoking is linked to impaired
collagen maturation.
• Hernias are more common in elderly people owing to degenerative
weakness of muscles and fibrous tissue.
• Incisional hernias are more common after wound complications and in
patients with a high body mass index, the surgeon and the way the
abdominal wall was closed.

42. References
1. Bailey & Love’s Short Practice of Surgery, 28th Edition.
2. Sabiston Textbook of Surgery, 21st Edition.
3. Schwartz’z Principles of Surgery, 11th Edition.
4. Gray’s Anatomy for Students, 4th Edition.

43. THANK YOU