For surgical residents and medical students

1. ANATOMY OF THE ANTERIOR
ABDOMINAL WALL AND INCISIONS
BY
DR GEORGE OWUSU

2. OUTLINE
• Introduction
• Embryology of the anterior abdominal wall
• Divisions of the anterior abdominal wall
• Components of the anterior abdominal wall
• Parietal peritoneum and posterior part of the
anterior abdominal wall
• Applied anatomy
• Abdominal Incisions
• Principles of making abdominal incisions
• Types of abdominal incisions
• Complications
• conclusion

3. INTRODUCTION
• The abdomen houses several viscera responsible
for different bodily functions.
• The anterior abdominal wall is well crafted to
keep these viscera in place and protected from
the external environment.
• However with aberrations involving the intra-
abdominal contents, the anterior abdominal wall
serves as a gateway to the abdomen, where
several important and life saving incisions could
be made to access the impaired viscera.

4. EMBRYOLOGY OF THE ANTERIOR
ABDOMINAL WALL
• By the end of the 5th week,
somites derived from the para-
axial mesoderm differentiate
into two groups of prospective
muscle cells.
• Hypomeres derived from the
dorsolateral part and epimeres
from its dorsomedial part.
• The hypomeres in the abdominal
region splits to give rise to the
external oblique, internal
oblique and transversus
abdominis muscle.

5. EMBRYOLOGY OF THE ANTERIOR
ABDOMINAL WALL
• A ventral longitudinal
column from the
hypomeric tip gives rise
to the Rectus
abdominis.
• Nerves innervating
segmental muscles also
divide with ventral rami
innervating the
hypomere derivatives

6. DIVISIONS OF THE ANTERIOR
ABDOMINAL WALL
• Divided into nine regions by
two paramedian vertical and
horizontal lines.
• Paramedian line, lies in a
plane joining the
midclavicular line to the mid-
inguinal line bilaterally.
• The upper transverse line lies
in the transpyloric plane.
• Lower transverse line lies in
the intertubercular plane.

7. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• Composed of four
major layers:
– Skin
– Subcutaneous layer
– Muscular layer
– Parietal peritoneal layer
• Their accompanying
neurovascular bundle
and lymphatics.

8. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• SKIN:
• Continuous from the chest
wall with termination of
the rib cage.
• Thinner in texture than the
back.
• Of surgical importance are
the Langers tension line
arranged transversely.
• Incisions made in their
direction gives
cosmetically better scars.

9. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• Skin:
• Blood supply: from
cutaneous branches of;
– lumbar artery,
– superior and inferior
epigastric arteries
• Venous drainage:
– Great saphenous vein from
areas below the umbilicus
– Lateral thoracic vein from
areas above the umbilicus.

10. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• Skin:
• Nerve supply:
– Anterior and lateral
cutaneous branches of
ventral rami T7-L1 spinal
nerves segmentally.
• Lymph drainage:
– Above the umbilicus to the
pectoral group of axillary
nodes
– Below the umbilicus to the
medial group of superficial
inguinal lymph nodes

11. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• SUBCUTANEOUS FASCIAL
LAYER:
• Made up of two parts:
– Fatty superficial layer of
campers
– Membranous layer of scarpa
• The membranous layer
allows the fatty layer to
slide freely over the
underlying structures.
• Extends over the penis and
scrotum as the superficial
fascia of bucks.
• And perineum as the colle’s
fascia

12. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• MUSCULAR LAYER:
• Three flat muscles:
– External oblique muscle
– Internal oblique muscle
– Transversus abdominis
• Two vertical muscles
– Rectus abdominis
– pyramidalis

13. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• EXTERNAL OBLIQUE MUSCLE:
• Made up of fleshy and aponeurotic
parts.
• origin: external surfaces of 5th-12th
ribs
• INSERTIONS:
– Anterior half of the iliac crest
– The pubic tubercle
– Linea alba
• Nerve supply: ventral rami of T7- T12
• Blood supply: superior and inferior
epigastric arteries
• Action: compress and supports
abdominal viscera
• Flexes and rotates the trunk

14. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• Ligaments and reflections
of the external oblique
aponeurosis:
– Inguinal ligament (of
Poupart)
– Lacunar ligament (of
Gimbernat)
– Pectineal ligament (of
Astley cooper)
– Reflected part of the
inguinal ligament

15. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• INTERNAL OBLIQUE MUSCLE:
• Origin:
– Thoracolumbar fascia
– iliac crest
– inguinal ligament
• Insertion:
– Linea alba
– Pubis via conjoint tendon
• Blood supply:
– Superior and inferior epigastric
– Deep circumflex iliac artery
• Nerve supply: ventral rami of
T7 – L1
• ACTION
– Compresses and supports
abdominal viscera
– Flexes and rotates the trunk

16. COMPONENTS OF THE ANTERIOR ABDOMINAL
WALL• TRANSVERSUS ABDOMINIS:
• Origin:
– Internal surfaces costal
cartilage of 7th-12th ribs
– Thoracolumbar fascia
– iliac crest
– inguinal ligament
• Insertion:
– Linea alba
– Pubis via conjoint tendon
• Blood supply:
– Superior and inferior epigastric
– Deep circumflex iliac artery
• Nerve supply: ventral rami of
T7 – L1
• ACTION
– Compresses and supports
abdominal viscera
– Flexes and rotates the trunk

17. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• RECTUS ABDOMINIS
• Origin:
– Pubic symphysis (medial lip)
– Pubic crest (lateral lip)
• Insertion:
– Xyphoid process
– Costal cartilage of T5 – T7
• Blood supply:
– Superior and inferior
epigastric
• Nerve supply: ventral rami
of T7 – L1
• Action:
– Major flexor of the trunk
– Compresses and supports
abdominal viscera

18. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• PYRAMIDALIS:
• Origin:
– Body of pubis
• Insertion:
– Linea alba
• Blood supply:
– Inferior epigastric artery
• Nerve supply: ventral
rami of T12
• ACTION
– Tenses the linea alba

19. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• RECTUS SHEATH:
• Encloses the vertical
muscles.
• Formed by splitting and
fusion of the flat muscle
aponeurosis
• Splitting of the internal
oblique aponeurosis
forms a shallow groovy
curve ‘semi-lunar line’.

20. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• INGUINAL CANAL:
• Oblique intramuscular slit,
about 4cm long, above
medial half of the inguinal
ligament.
• Extends from the deep ring
to the superficial ring.
• Boundaries:
• Roof: lower edges of the
internal oblique and
transversus abdominis
muscles.

21. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• INGUINAL CANAL:
• Floor: inguinal ligament
(reinforced medially by the
lacunar ligament)
• Anterior wall: external
oblique aponeurosis
(reinforced laterally by
internal oblique muscle
• Posterior wall:
transversalies fascia
(reinforced medially by the
conjoint tendon)
• Contents:
– Spermatic cord and
ilioinguinal nerve in males;
round ligament and
ilioinguinal nerve in females.

22. COMPONENTS OF THE ANTERIOR
ABDOMINAL WALL
• Parietal peritoneum and
posterior surface:
• Contains five folds in the
infraumbilical region:
– Median umbilical fold
– Two medial umbilical fold
– Two lateral umbilical fold
• Falciform ligament in the
in the supraumbilical
region

23. APPLIED ANATOMY
• CONGENITAL DEFECTS:
• Omphalocele
• Gastroschisis
• Umbilical hernia
• Prune belly syndrome
• ACQUIRED DEFECTS:
• Spigelian hernia
• Inguinal hernias
– Direct
– indirect

24. INCISIONS
• Incisions are surgical wounds made on the skin and
deepened to gain access to an internal structure or
organ.
• PRINCIPLES OF ABDOMINAL INCISIONS:
– It should provide adequate exposure of the organ or
organs to be dealt with.
– It should be capable of extension
– minimal damage to neurovascular bundles and muscles
– Secured closure should be achievable
– Provide a cosmetically acceptable scar
– Peritoneal drainage tubes should be inserted through a
separate incision
– Wound should be closed in layers

25. CLASSIFICATION OF ABDOMINAL
INCISIONS
• VERTICAL INCISIONS:
– Midline incision
– Paramedian incision
• TRANVERSE AND OBLIQUE
INCISIONS:
– Kocher's subcostal incision
• Chevron (rooftop)
modification
• Mercedes Benz modification
– Transverse muscle dividing
incision
– Mc Burney's Grid iron or
muscle diving incision
– Lanz incision
– Rutherford Morrison incision
– Pfannenstiel incision
– Maylard incision
– Groin skin crease

26. MIDLINE INCISION
• Vertical incision made in
the midline.
• Could be supraumbilical
or subumblical or a
combination of both.
• It divides through the
skin, linea alba and
peritoneum
• It is almost bloodless
• Nerves are spared

27. MIDLINE INCISION
• It is quick and easy to
close.
• No muscles divided
• Supraumbilical midline
incisions provides quick
access to the stomach
and duodenum, spleen,
liver especially left lobe.
• The subumbilical –
intestines, appendix,
pelvic viscera

28. PARAMEDIAN INCISION (UPPER OR
LOWER, RIGHT OR LEFT)
• Incision is made 2-5cm
lateral to the midline.
• Skin and subcutaneous
tissue incised – anterior
layer of rectus sheath
opened and stripped off
muscle – rectus muscle
reflected laterally and
posterior layer of sheath
and peritoneum opened.

29. PARAMEDIAN INCISION (UPPER OR
LOWER, RIGHT OR LEFT)
• Has the advantage of offsetting the vertical incision to
the right or left with access to lateral structures such as
the spleen and kidneys.
• Closure is theoretically more secure.
• PARAMEDIAN MUSCLE SPLITTING INCISION:
• Could be done instead of lateral retraction of the
rectus abdominis
• Muscle splitted in line of incision
• Disadvantage: atrophy of medial part and risk of
herniation.

30. KOCHERS (SUBCOSTAL) INCISION:
• Started at midline about 2cm
below the xyphoid process,
extending outwards and
parallel to the costal margin.
• Right incisions affords good
access to the gall bladder and
billiary tract.
• Left incisions affords access to
the spleen.
• N/B Mini-lap cholecystectomy -
A small 5-10 cm incision could
be done in the right subcostal
area for cholecystectomy

31. MODIFICATIONS OF KOCHERS
INCISION
• CHEVRON (ROOFTOP):
• Incision continued
across midline as
double kochers incision.
• Useful in carrying out
gastrectomy,
renovascular surgeries,
liver transplantation,
bilateral adrenalectomy.

32. MODIFICATIONS OF KOCHERS
INCISION
• MERCEDES BENZ
INCISION:
• Consist of bilateral low
kochers incision and a
midline incision up to
the xiphisternum.
• Gives access to the
upper abdominal
viscera especially the
diaphragmatic hiatuses.

33. Mc Burney’s grid iron or muscle split
incision:
• Oblique incision made at
Mc Burney’s point on the
skin and subcutaneous
tissues.
• External oblique
aponeurosis is divided in
direction of its fibers –
underlying internal oblique
is opened by splitting along
the line of its fibers.
• Used for appendicectomy
and on the left for drainage
of diverticular abscess.

34. Lanz incision
• A modification of the
MC Burney’s incision,
made with a transverse
skin incision .
• Gives a better cosmetic
outcome.

35. RUTHERFORD MORRISON INCISION
(OBLIQUE MUSCLE CUTTING INCISION)
• Similar to the grid iron’s
incision, however cuts
through the underlying
muscles.
• Used for appendicectomy
• Useful in right and left
sided colonic resections,
caecostomy or sigmoid
colostomy

36. TRANSVERSE MUSCLE DIVIDING
INCISION
• This is done at a level
above the umbilicus.
• Following a transverse
skin and subcutaneous
tissue dissection, the
rectus sheath and
muscles are divided
transversely and
peritoneum afterwards.
• It is preferred in
newborns and infants,
because more abdominal
exposure will be gained.

37. PFANNENSTIEL INSCISION
• Used frequently by gynecologist
and urologist to access pelvic
organs.
• Transverse curvilinear skin
incision made about 12cm long
on skin fold, about 5cm above
the pubic symphysis.
• Deepened through the
subcutaneous tissue with
anterior rectus sheath divided
along length of incision and
separated from muscle.
• The rectus muscles are retracted
laterally and peritoneum opened
vertically in midline.

38. MAYLARD(TRANVERSE MUSCLE
CUTTING) INCISION
• Transverse incision placed a
little higher than the
Pfannenstiel.
• It differs from the
Pfannenstiel incision by
transverse division of the
rectus sheath and rectus
muscle, which could be
extended to the flat muscles.
• Gives wider exposure to
pelvic structures

39. COMPLICATIONS OF INCISIONS
• Nerve injury
• Hematoma formation
• Surgical site infection
• Wound dehiscence and burst abdomen
• Incisional hernia

40. PRINCIPLE OF WOUND CLOSURE
• GOAL: To approximate and not strangulate
• Proper choice of suture materials and
technique.
• Elimination of dead space
• Closing with sufficient tension (tight enough
to seal wound but not strangulate)
• Proper immobilisation of wound

41. CONCLUSION
• The anterior abdominal wall is well crafted to
give support and protection to the intra
abdominal viscera.
• However defects in its wall could lead to
protrusions of such viscera.
• Valuable incisions when well placed on the
abdomen, gives life saving access to the intra-
abdominal organs, avoiding complications and
cosmetically acceptable scars.

42. THANK YOU!!!

43. REFERENCES
• Chummy sinnatamby. Last’s anatomy 12th edition
2011.
• Keith Moore et al. clinically oriented anatomy 6th
edition 2010.
• Frank Netter. Atlas of human anatomy 6th edition
2014
• Badoe E.A et al. Principles and practice of surgery
including pathology in the tropics.3rd edition
2000:
• Siram Bhat M. SRBs manual of surgery. 3rd edition
2009: