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DEPARTMENT OF ANATOMY
SCHOOL OF BASIC MEDICAL SCIENCES
IGBINEDION UNIVERSITY, OKADA
LECTURE NOTES ON GROSS ANATOMY OF THE ABDOMEN
ANA 221

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GROSS ANATOMY OF THE ABDOMEN
We know that body is divided into regions
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e upper limb, lower limb thorax &abdomen, pelvis
and perineum, head and neck
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CONTENTS OF THE ABDOMEN
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Abdominal cavity
Peritoneal cavity
Abdominal organs or viscera
Abdominal wall

The Abdominal organs or viscera or gastrointestinal organs includes
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Inferior part of the oesophagus
The stomach
Small intestine (duodenum, jejunum and ileum)
Large Intestine (colon)
Liver and biliary system (gall bladder & bile ducts)
The pancreas
The kidneys & superior part of the ureters
The suprarenal gland (adrenal glands)
The spleen
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The diaphragm forms the roof of the abdomen and it is the boundary between the thorax and
the abdomen
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The abdominal cavity (space of the abdomen) extends superiorly into the thoracic cage
as far as the 4th intercostal space offering protections to some abdominal viscera such as the
spleen, liver, parts of the stomach and kidney
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LOCATION OF ABDOMINAL VISCERA
Two methods are used to describe the location of abdominal organs
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Two horizontal planes or lines
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Transtubercular- passes through the body of L5 vertebra &the iliac tubercles
Two vertical planes or lines
Mid clavicular planes- passes through the midpoint of the clavicle (app
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Using four quadrants of the abdominal cavity defined or described by two planes
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SUMMARY OF ORGANS LOCATED IN THE FOUR QUADRANTS

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RIGHT UPPER QUADRANT
(RUQ)
Right lobe of liver
Gallbladder
Stomach- pylorus
Duodenum 1-3rd part
Pancrease-head
Right kidney/suprarenal gland
Right colic/hepatic flexure
Ascending colon- superior part

LEFT UPPER QUADRANT (LUQ)
Left lobe of liver
spleen
Stomach –body/main part
Jejunum & proximal ileum
Body and ail of pancrease
Left kidney/suprarenal gland
Left colic/splenic flexure
Transverse colon
Descending colon- superior prt

RIGHT LOWER QUADRANT
LEFT LOWER QUADRANT
Caecum
Sigmoid colon
Vermiform appendix
Descending colon-inferior part
Most of ileum
left ovary
Ascending colon-inferior part
left uterine tube
Right ovary
Left spermatic cord-abdominal part
Right uterine tube
Uterus if enlarged
Right spermatic cord-abdominal
Urinary bladder if enlarged
part
Uterus if enlarged
Urinary bladder if enlarged
THE ABDOMINAL WALL
It represents the boundaries of the abdominal cavity and it is divided into anterior (front),
lateral (sides) and posterior (back)
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Involve in actions that increases intra-abdominal pressure
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Emmanuel
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Bienonwu

SURFACE ANATOMY OF THE ABDOMINAL WALL
Features seen on the anterolateral abdominal wall includes
 The umbilicus-----most obvious features &represents the former site of attachment of
the umblical cord
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Lies in the anterior median line and is clearly
visible in thin muscular persons
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It indicates the lateral border of the rectus
abdominus muscle
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In the inferior part of the wall, just above the inguinal ligament (below the umbilicus)
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The superficial vessels and nerves run between these two layers
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It is also continuous with the
superficial fascia of the perineum (Colles fascia)
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Muscles of the anterolateral abdominal wall
The anterolateral abdominal all contains four important muscles
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And ultimately
form the RECTUS SHEALTH
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The aponeuroses of all the flat muscles become entwined in the midline, forming the lineaalba(a
fibrous structure that extends from the xiphoid process of the sternum to the pubic symphysis)
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muscles of the anterolateral abdominal wall

External Oblique
The external oblique is the largest and most superficial flat muscle in the abdominal wall
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Inferiorily the muscle fibers folds back on itself to form the inguinal
ligament between the anterior superior iliac spine and the pubic tubercle
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Functions: Contralateral rotation of the trunk, flexes trunk, compresses and support
abdominal organs
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Internal Oblique
The internal oblique lies deep to the external oblique
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Attachments: Originates from the inguinal ligament, iliac crest and lumbodorsal fascia,
and inserts into ribs 10-12 and lineaalba
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Innervation: Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of
the lumbar plexus
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Deep to this muscle is a well-formed layer of fascia, known
as the transversalis fascia
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Inserts into the conjoint tendon,
xiphoid process, lineaalba and the pubic crest
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Innervation: Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of
the lumbar plexus
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Rectus Abdominis
The rectus abdominis is long, paired muscle, found either side of the midline in the abdominal
wall
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The lateral borders of the muscles create a surface
marking known as thelineasemilunaris
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The tendinous intersections and the lineaalba give rise to the ‘six pack’ seen in individuals with a
well-developed rectus abdominis
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Functions: As well as assisting the flat muscles in compressing the abdominal viscera,
the rectus abdominis also stabilises the pelvis during walking, and depresses the ribs,
flexes the trunk
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Pyramidalis
This is a small triangular muscle, found superficially to the rectus abdominis
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Attachments: Originates from the pubic crest and pubic symphysis before inserting into
the lineaalba
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Innervation: Subcostal nerve (T12)
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It has an anterior
and posterior wall for most of its length:
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The anterior wall is formed by the aponeuroses of the external oblique, and of half of the
internal oblique
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That is the internal oblique divides into two
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With the rectus abdominus and pyramidialis
muscle in between
Approximately midway between the umbilicus and the pubic symphysis, all the aponeuroses
move to the anterior wall of the rectus sheath
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The inferior one
third of the posterior wall is deficient (incomplete)
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CONTENTS OF THE RECTUS SHEALTH
 Rectus abdominus muscle
 Pyramidailis muscle
 Superior and Inferir epigastric vessels
 End of lower six thoracic nerves
 Lower six intercoastal vessels
BLOOD SUPPLY TO THE ANTEROLATERAL ABDOINAL WALL
 Branches of the Internal thoracic artery (Superior Epigastric and Musculophrenic artery)
 Branches of the external iliac artery (Inferior epigastric and deep circumflex artery)
 Inferior phrenic artery , branch of the abdominal aorta
 Lower posterior intercostals and subcostal arteries ( branches of thoracic aorta)
 Lumbar arteries, from abdominal aorta
NERVE SUPPLY
 The skin and muscles of the wall are supplied mainly by thoracoabdominal (T7-T11) nerves
and the subcoastal nerve (T12)
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Palpation is done with warm hands
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Normally intense guarding (spasms) occurs during palpation
when an organ e
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The
involuntary muscular spasm tends to protect the viscera from pressure which is painful when
an abdominal infection is present
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A REFLEX
The abdominal wall is the only protection to most of the abdominal organs
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It might produce contraction of the muscles
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This article discusses all hernia types and their treatments
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In women, the inguinal canal contains the round

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ligament that gives support for the womb
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This is the most common
type of hernia, and affects men more often than women
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Femoral hernias are much less common than inguinal hernias and mainly
affect older women
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Hiatal (hiatus) hernia: Part of the stomach pushes up into the chest cavity through an
opening in the diaphragm (the horizontal sheet of muscle that separates the chest from the
abdomen)
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Epigastric hernia: Fatty tissue protrudes through the abdominal area between the navel
and lower part of the sternum (breastbone)
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Diaphragmatic hernia: Organs in the abdomen move into the chest through an opening
in the diaphragm
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They are based on some anatomical
principles( anatomical basis)
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3
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5
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Muscles fibers should be split rather than cut (transected) as this can cause irrevisable necrosis
(death) of the muscle fibers
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therefore the nerves can easily be
located and preserved
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Nerves should not be divided or cut, cutting a motor nerve paralyses the muscle fibers it supplies,
thereby weakening the anterolateral abdominal wall
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(Skin—linea alba---Trasversalis fascia-extra peritoneal fat—
peritoneum) It can be extended the whole length of the abdomen by curving around the
umbilicus
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However the poor vascular nature of the linea alba may makeit undergo necrosis and
subsequentlydegeneration after incision if the edges are not properly aligned during closure
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Paramedian
Similar to the median incision, but is performed parallel or laterally to the lineaalba, providing
access to more lateral structures (kidney, spleen and adrenals)
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(Skin—anterior
layer of rectus—posterior layer of rectus—peritoneum)

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Kocher
A Kocher incision ③ begins inferior to the xiphoid process and extends inferolaterally in
parallel to the right costal margin
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Two modifications and extensions of the Kocher incision are possible:
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Chevron / rooftop incision or modification ④ – the extension of the incision to the
other side of the abdomen
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This may be used for the same indications
as the Chevron incision, however classically seen in liver transplantation
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① Midline incision, ②Paramedian incision, ③ Kocher
incision, ④ Rooftop modification and ⑤ Mercedes Benz modification
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McBurney incision is performed at McBurney’s point (1/3 of the distance between the ASIS and
the umbilicus) and is used in an open appendicectomy
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(Skin—
external oblique muscle---internal oblique---transverse abdominus---peritoneum)
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The iliohypogastric nerve running deep in the
internal oblique is identified and preserved
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It is used for most gynecological
and obstetrical operations
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g for cesarean sectionand removal of tubal preganacy) Skin—
anterior layer of rectus—transversalis fascia (no posterior layer of rectus)

TRANSVERSE INCISION
made inferior and lateral to the umbilicus
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transverse incisions are made through the tendinous nsertions because
cutaneous nerves and branches of the superior epigastric vessels pierce these fibrous regions of
the muscle
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