Abdominal wall.pptx

12/28/2022
2 Yared T (Ass. Professor)

The abdominal wall
 The abdomen is a roughly cylindrical chamber extending from
the inferior margin of the thorax to the superior margin of the
pelvis.
 It is a flexible, dynamic container, housing most of the organs
of the alimentary system and part of the urogenital system.
 Containment of the abdominal organs and their contents is
provided by:
 musculoaponeurotic walls anterolaterally,
 the diaphragm superiorly, and
 the muscles of the pelvis inferiorly.
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Yared T (Ass. Professor)

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Abdominal wall…
 The dynamic, multi-layered, musculoaponeurotic abdominal
walls not only contract to increase intra-abdominal pressure
but also distend considerably, accommodating expansions
caused by ingestion, pregnancy, fat deposition, or pathology.
 The anterolateral abdominal wall and several organs lying
against the posterior wall are covered on their internal aspects
with a serous membrane or peritoneum that reflects onto the
abdominal viscera, such as the stomach, intestine, liver, and
spleen.
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The abdominal cavity:
 Forms the superior and major part of the abdominopelvic
cavity, the continuous cavity that extends between the thoracic
diaphragm and pelvic diaphragm.
 has no floor of its own because it is continuous with the pelvic
cavity.
 The plane of the pelvic inlet (superior pelvic aperture)
arbitrarily, but not physically, separates the abdominal
and the pelvic cavities.
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The abdominal cavity:
 extends superiorly into the osseocartilaginous
thoracic cage to the 4th intercostal space.
 the more superiorly placed abdominal organs
(spleen, liver, part of the kidneys, and stomach) are
protected by the thoracic cage.
 The greater pelvis supports and partly protects the
lower abdominal viscera (part of the ileum, cecum,
and sigmoid colon).
 is the location of most digestive organs, parts of the
urogenital system (kidneys and most of the
ureters), and the spleen.
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Abdominal quadrants & regions
 Nine regions of the abdominal cavity are used to
describe the location of abdominal organs, pains, or
pathologies.
 The regions are delineated by four planes:
 two sagittal (vertical) and two transverse (horizontal)
planes.
 The two sagittal planes are usually the midclavicular planes
that pass to the midinguinal points.
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Abdominal quadrants & regions
 Most commonly, the transverse planes are:
 the subcostal plane, passing through the inferior border of
the 10th costal cartilage on each side, and
 the transtubercular plane, passing through the iliac
tubercles
 Both of these planes have the advantage of
intersecting palpable structures.
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….
 Clinicians use the transpyloric and interspinous planes to
establish the nine regions.
 The transpyloric plane:
 extrapolated midway between the superior borders of the
manubrium of the sternum and the pubic symphysis
(typically the L1 vertebral level),
 commonly transects the pylorus when the patient is
recumbent (supine or prone).
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…
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 The transpyloric plane is a useful landmark because it also
transects many other important structures:
 the fundus of the gallbladder,
 neck of the pancreas,
 origins of the superior mesenteric artery (SMA) and
hepatic portal vein,
 root of the transverse mesocolon,
 duodenojejunal junction, and
 hila of the kidneys.

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ANTEROLATERAL ABDOMINAL WALL
 Abdominal wall is subdivided into the anterior wall, right and left
lateral walls, and posterior wall for descriptive purposes.
 The wall is musculoaponeurotic, except for the posterior wall,
which includes the lumbar region of the vertebral column.
 The anterolateral abdominal wall extends from the thoracic
cage to the pelvis.
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Anterolateral abdominal wall...
 The anterolateral abdominal wall is bounded:
 superiorly by:
o the cartilages of the 7th-10th ribs and
o the xiphoid process of the sternum, and
 inferiorly by:
o the inguinal ligament and
o the superior margins of the anterolateral aspects of the
pelvic girdle (iliac crests, pubic crests, and pubic
symphysis).
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Anterolateral abdominal wall…
 The anterolateral abdominal wall consists of:
 skin
 subcutaneous tissue (superficial fascia) composed mainly of
fat,
 muscles and their aponeuroses and
 deep fascia,
 extraperitoneal fat, and
 parietal peritoneum .
 The skin attaches loosely to the subcutaneous tissue, except
at the umbilicus, where it adheres firmly.
 the anterolateral wall includes three musculotendinous
layers; the fiber bundles of each layer run in different
directions.
 This three-ply structure is similar to that of the intercostal
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Fascia of the Anterolateral Abdominal
Wall
 The subcutaneous tissue over most of the wall includes a
variable amount of fat.
 It is a major site of fat storage.
 Males are especially susceptible to subcutaneous
accumulation of fat in the lower anterior abdominal wall.
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Fascia of the Anterolateral Abdominal
Wall
 Superior to the umbilicus, the subcutaneous tissue is consistent
with that found in most regions.
 Inferior to the umbilicus, the deepest part of the subcutaneous
tissue is reinforced by many elastic and collagen fibers, so it
has two layers:
 the superficial fatty layer (Camper fascia) and the deep
membranous layer (Scarpa fascia) of subcutaneous tissue.
 The membranous layer continues inferiorly into the perineal
region as the superficial perineal fascia (Colles fascia), but
not into the thighs. 12/28/2022
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Superficial fascia…
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Muscles of Anterolateral Abdominal Wall
 There are five (bilaterally paired) muscles in the anterolateral
abdominal wall:
 three flat muscles and
 two vertical muscles.
 The three flat muscles are the external oblique, internal
oblique, and transversus abdominis.
 The muscle fibers of these three concentric muscle layers
have varying orientations, with the fibers of the outer two
layers running diagonally and perpendicular to each other for
the main part, and the fibers of the deep layer running
transversely. 12/28/2022
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Muscles of Anterolateral Abdominal Wall
 All three flat muscles are continued anteriorly and medially as
strong, sheet-like aponeuroses.
 the aponeuroses form the tough, aponeurotic, tendinous rectus
sheath enclosing the rectus abdominis muscle.
 The aponeuroses then interweave with their fellows of the
opposite side, forming a midline raphe the linea alba, which
extends from the xiphoid process to the pubic symphysis.
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Anterolateral muscles…
 The two vertical muscles of the anterolateral abdominal wall,
contained within the rectus sheath, are the large rectus
abdominis and the small pyramidalis.
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Muscles
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1. External Oblique Muscle
 is Largest & most superficial flat muscle
 its Fibers run inferiomedially
2. Internal Oblique Muscle
 Intermediate of the three flat abdominal wall
muscles
 its Muscle fibers run superomedially

Muscles…
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 Inferiorly, the external oblique aponeurosis attaches to the
pubic crest medial to the pubic tubercle.
 The inferior margin of the external oblique aponeurosis is
thickened as an under curving fibrous band with a free
posterior edge that spans between the ASIS and the pubic
tubercle as the inguinal ligament.

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muscles…
3. Transverse Abdominis Muscle
 The innermost of the three flat muscles
 It run more or less transversely
 Between the internal oblique and the transversus abdominis
muscles is a neurovascular plane, which corresponds with a
similar plane in the intercostal spaces.
 The neurovascular plane of the anterolateral abdominal wall
contains the nerves and arteries supplying the anterolateral
abdominal wall.
 In the anterior part of the abdominal wall, the nerves and
vessels leave the neurovascular plane and lie mostly in the
subcutaneous tissue. 12/28/2022
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4. Rectus Abdominis Muscle
 A long, broad, strap-like muscle
 It is a Principal vertical muscle of anterior abdominal wall
 The rectus abdominis is three times as wide superiorly as
inferiorly; it is broad and thin superiorly and narrow and thick
inferiorly.
 It is enclosed in the rectus sheath.
 Paired rectus muscles are separated by linea alba
 It Has three or more tendinous intersections
5. Pyramidalis Muscle
 Small triangular muscle
 May be absent in approximately 20% of people
 Lie anterior to the inferior part of rectus abdominis & pubis
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RECTUS SHEATH, LINEA ALBA, AND
UMBILICUS
 The rectus sheath is the strong, incomplete fibrous
compartment of the rectus abdominis and pyramidalis
muscles.
 It contains:
 the superior and inferior epigastric arteries and veins,
 lymphatic vessels, and
 distal portions of the thoracoabdominal nerves ( T7-T12).
 it is formed by the decussation and interweaving of the
aponeuroses of the flat abdominal muscles.
 The external oblique aponeurosis contributes to the anterior
wall of the sheath throughout its length.
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RECTUS SHEATH, LINEA ALBA, AND UMBILICUS
 The superior 2/3rd of the internal oblique aponeurosis splits into
two layers (laminae) at the lateral border of the rectus
abdominis; one lamina passing anterior to the muscle and the
other passing posterior to it.
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UMBILICUS
 approximately 1/3rd of the distance from the umbilicus to the
pubic crest, the aponeuroses of the three flat muscles pass
anterior to the rectus abdominis to form the anterior layer of
the rectus sheath, leaving only the relatively thin transversalis
fascia to cover the rectus abdominis posteriorly.
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UMBILICUS
 A crescentic arcuate line
demarcates the transition
between the aponeurotic
posterior wall of the sheath
covering the superior 3/4th
of the rectus and
 the transversalis fascia
covering the inferior
quarter.
 Throughout the length of
the sheath, the fibers of
the anterior and posterior
layers of the sheath
interlace in the anterior
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UMBILICUS
 The posterior layer of the rectus sheath is also deficient
superior to the costal margin.
 Hence, superior to the costal margin, the rectus abdominis
lies directly on the thoracic wall.
 Rectus sheath is interrupted by 3 tendinous
intersections:
 one near the umbilical level
 the other is near the xiphoid process
 the third is about midway b/n the two
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The linea alba
 The linea alba, running vertically the length of the anterior
abdominal wall and separating the bilateral rectus sheaths.
 The linea alba transmits small vessels and nerves to the
skin.
 In thin muscular people, a groove is visible in the skin
overlying the linea alba.
 All layers of the anterolateral abdominal wall fuse at the
umbilicus.
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FUNCTIONS AND ACTIONS OF ANTEROLATERAL ABDOMINAL
MUSCLES
The muscles of the anterolateral abdominal wall:
 Form a strong expandable support for the anterolateral
abdominal wall.
 Support the abdominal viscera and protect them from most
injuries.
 Compress the abdominal contents to maintain or increase the
intra-abdominal pressure and, in so doing, oppose the
diaphragm (increased intra-abdominal pressure facilitates
expulsion).
 Move the trunk and help to maintain posture
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Neurovasculature of Anterolateral Abdominal
Wall
Nerves of Anterolateral Abdominal Wall
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 The skin and muscles of the anterolateral abdominal wall
are supplied mainly by the following nerves:
o Thoracoabdominal nerves: abdominal parts of the
anterior rami of the inferior six thoracic spinal nerves (T7-
T11).
o Lateral (thoracic) cutaneous branches: of the thoracic
spinal nerves T7-T9 or T10.
o Subcostal nerve: anterior ramus T12.
o Iliohypogastric and ilioinguinal nerves: terminal
branches of the anterior ramus of L1.

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 Anterior abdominal cutaneous branches of
thoracoabdominal nerves:
 T7-T9 supply the skin superior to the umbilicus.
 T10 supplies the skin around the umbilicus.
 T11, plus the cutaneous branches of the
subcostal (T12), iliohypogastric, and ilioinguinal
(L1), supply the skin inferior to the umbilicus.
 During their course through the anterolateral
abdominal wall, the thoracoabdominal, subcostal,
and iliohypogastric nerves communicate with each
other. Yared T (Ass. Professor)

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Vessels of Anterolateral Abdominal Wall
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 The primary blood vessels (arteries & veins) of the
anterolateral abdominal wall are:
 Superior epigastric vessels and branches of the
musculophrenic vessels from the internal thoracic
vessels.
 Inferior epigastric and deep circumflex iliac
vessels from the external iliac vessels.
 Superficial circumflex iliac and superficial
epigastric vessels from the femoral artery and
greater saphenous vein, respectively.
 Posterior intercostal vessels of the 11th intercostal
space & anterior branches of subcostal vessels.

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Lymphatic drainage of the anterolateral abdominal
wall
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 Lymphatic drainage of the anterolateral abdominal wall
follows the following patterns :
a. Superficial lymphatic vessels accompany the
subcutaneous veins:
 Superior to the transumbilical plane drain mainly to the
axillary lymph nodes; however, a few drain to the
parasternal lymph nodes.
 Inferior to the transumbilical plane drain to the superficial
inguinal lymph nodes
b Deep lymphatic vessels accompany the deep veins of
the abdominal wall and drain to:
 external iliac
 common iliac
 right &left lumbar (caval and aortic) lymph nodes

Lymphatics & superficial veins of anterolateral abdominal wall
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Clinical Anatomy of the Abdominal Wall
A. Signs of Pregnancy
1. Linea nigra:
 dark (reddish brown) line extend from xiphoid process to
symphysis pubis along linea alba but more intense below
umbilicus.
2. Striae gravidarum:
 bands of short reddish-brown lines found on abdominal
wall, buttocks & thigh due to over distension
 after parturition white lines called linea albicantes remain at
the place of the striae gravidarum.
B. Caput medusae:
 dilated & tortuous paraumbilical veins radiating from the
umbilicus due to portal hypertension 12/28/2022
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Cont.
C. McBurney’s point:
 a point found at lateral 1/3rd & medial 2/3rd of the line joining
right anterior superior iliac spine & umbilicus.
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Internal Surface of Anterolateral Abdominal Wall
 The internal (posterior) surface of the anterolateral abdominal
wall is covered with transversalis fascia, a variable amount of
extraperitoneal fat, and parietal peritoneum.
 The infraumbilical part of this surface exhibits five umbilical
peritoneal folds passing toward the umbilicus, one in the
median plane and two on each side:
 Median umbilical fold (1)
 Medial umbilical fold (2)
 Lateral umbilical fold (2)
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1. Median umbilical fold extends from the apex of the
urinary bladder to the umbilicus and covers the median
umbilical ligament, a fibrous remnant of the urachus
that joined the apex of the fetal bladder to the
umbilicus.
2. Two medial umbilical folds, lateral to the median
umbilical fold, cover the medial umbilical ligaments,
formed by occluded parts of the umbilical arteries.
3. Two lateral umbilical folds, lateral to the medial
umbilical folds, cover the inferior epigastric vessels
and therefore bleed if cut.
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Posterior aspect of anterolateral
abdominal wall of a male
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Inguinal Region
 The inguinal region or groin,
extends between the ASIS
and pubic tubercle.
 It is an important area
anatomically and clinically:
 anatomically because it is a
region where structures exit
and enter the abdominal
cavity
 clinically because the
pathways of exit and
entrance are potential sites
of herniation
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Inguinal Canal
 The inguinal canal is formed in relation to the relocation of the
testis during fetal development.
 The inguinal canal in adults is an oblique passage
approximately 4 cm long directed infer medially through the
inferior part of the anterolateral abdominal wall.
 It lies parallel and superior to the medial half of the inguinal
ligament
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The main contents of the inguinal canal
are:
 the ductus deferens;
 the artery to ductus deferens (from
the inferior vesical artery);
 the testicular artery (from the
abdominal aorta);
 the pampiniform plexus of veins
(testicular veins);
 the cremasteric artery and vein
(small vessels associated with the
cremasteric fascia);
 the genital branch of the
genitofemoral nerve (innervation
to the cremasteric muscle);
 sympathetic and visceral afferent
nerve fibers;
 lymphatics;
 remnants of the processus
vaginalis.
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• The inguinal canal has an opening at each end:
A. Deep (Internal) Inguinal Ring
 It is the entrance to the inguinal canal.
 It is located superior to the middle of the inguinal
ligament and lateral to the inferior epigastric artery.
 It is the beginning of an invagination in the transversals
fascia that forms an opening like the entrance to a cave
 Through this opening, the extra peritoneal ductus
deferens (vas deferens) and testicular vessels in males
(or round ligament of the uterus in females) pass to
enter the inguinal canal.
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Anterior wall Posterior wall
Roof Yared T (Ass. Professor)

B. Superficial (External) Inguinal Ring
 It is a triangular-shaped defect in the aponeurosis of the
external oblique muscle
 It lies immediately above and medial to the pubic tubercle.
 The margins of the ring, sometimes called the crura, give
attachment to the external spermatic fascia
 It is the exit by which the spermatic cord in males, or the
round ligament in females, emerges from the inguinal
canal
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Ligament, Iliopubic Tract & Inguinal Canal
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Abdominal Surgical Incisions
 Surgeons use various incisions to gain access to the
abdominal cavity.
 The incision that allows adequate exposure and, secondarily,
the best possible cosmetic effect, is chosen.
 The location of the incision also depends on the type of
operation, the location of the organ(s) the surgeon wants to
reach, bony or cartilaginous boundaries, avoidance of
(especially motor) nerves, maintenance of blood supply, and
minimizing injury to muscles and fascia of the wall while
aiming for favorable healing.
 Thus before making an incision, the surgeon considers the
direction of the muscle fibers and the location of the
aponeuroses and nerves. 12/28/2022
70

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Lines of Cleavage
 Tension lines in the
skin identify the
predominant
orientation of
collagen fiber
bundles.
 Clinically and
surgically significant
because cuts can
result in slow healing
and increased
scarring.
12/28/2022
Yared T.
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 ……….

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