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Gastrointestinal Module
Anterior Abdominal Wall, Peritoneal Cavity, Diaphragm
OUTLINE
I. Introduction
II. Abdominal Cavity
A. Surface Anatomy
B. Abdominal Wall
C. Faschia
D. Muscles
E. Nerves and Vessels
F. Internal Surface
G. Inguinal Region
III. Peritoneum and Peritoneal Cavity
A. Vessels and Nerves
B. Terminology
C. Greater Sac and Omental Bursa
IV. Diaphragm
A. Diaphragmatic Apertures
B. Actions of Diaphragm
16 November 2009
Dr. Jose Anthony Jocson


Extends to 4th intercostal space of thoracic cage
Continuous with pelvic cavity
9 Regions of Abdominal Cavity
- Right and left hypochondriac
- Right and left lumbar
- Right and left inguinal
- Epigastric
- Umbilical
- Hypogastric
I. Introduction
Abdomen – between thorax and pelvis
- Musculotendinous walls except posteriorly
- Abdominal wall encloses abdominal cavity – encloses
peritoneal cavity and viscera
II. Abdominal Cavity
4 Quadrants of the Abdominal Cavity
- Right and left upper quadrant
- Right and left lower quadrant
A. Surface Anatomy
Umbilicus
Linea alba – centrally, it represents the muscular aponeurosis
Xiphoid process
Pubic symphysis
Iliac crest
Anterior superior iliac spine
Semilunar lines – represent the lateral-most border of rectus
abdominus
- Tendinous intersections – represent points wherein rectus
abdominis is inserting
- Inguinal ligament
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Abdominal Wall
- Boundaries: abdominal walls, diaphragm, pelvis
- Features
 Surrounded by abdominal wall
 Diaphragm separates it from thoracic cage
 Peritoneal lining
Group 2
Anterolateral Abdominal Wall
- Mostly musculo-aponeurotic
- Indistinct boundaries between anterior and lateral part
C. Faschia
Layers of Anterolateral Wall
- Skin
- Camper’s faschia – fatty, superficial, subcutaneous tissue
 Where instrument is inserted in liposuction
- Scarpa’s faschia – membranous, deep, subcutaneous tissue
- Deep faschia / muscle layer
- Endoabdominal faschia / fat
- Parietal peritoneum
Aguila. Arano. Angeles. Balictar. Escobillo. Pena. Ronquillo. Tagalog. Uy. Yeo. Yu
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BATCH 2014  Anterior Abdominal Wall, Peritoneal Cavity, Diaphragm
* Muscles in anterolateral wall are quite thin that is why people
have died from liposuction (the machine/probe penetrates into
abdominal cavity and damages structures)
D. Muscle Layers
External oblique
Internal oblique
Transverse
abdominal
Superficial, inferomedially directed fibers (trouser
pockets)
Intermediate layer, fibers are at right angles to
external oblique (vest pockets)
Innermost, horizontal fibers
Vertical muscle, mostly enclosed by rectus sheath,
running vertically between tendinous intersections
(forms the ‘6-pack’)
Triangular muscle in rectus sheath, inferiorly
Rectus
abdominis
Pyramidal
Posterior layer
Crescentic/
Arcuate line
Nerves of Anterolateral Abdominal Wall
- Thoracoabdominal nerves (T7-T11)
 T7-T9 supply skin superior to umbilicus
 T10 supplies skin around umbilicus
 T11, T12, L1 supply skin inferior to umbilicus
- Subcostal nerves (T12)
- Iliohypogastric/ilioinguinal nerves
Vessels
- A means of collateral circulation
 If there is blockage of aorta, the blood can pass
through superior epigastric to inferior epigastric to
iliacs
- Superior epigastic artery
 Continuation of the internal thoracic artery
 Supplies upper rectus abdominis
 Supplies sensation to level of umbilicus
 Anastomoses with inferior epigastric artery
- Inferior epigastric artery
 From external iliac artery
 Anastomoses with the superior epigastric artery with
the umbilical region
- Superficial circumflex iliacs
- Superficial epigastrics
- Anterior and collateral branches of the posterior intercostals
vessels
Surgical Incisions
- Midline incisions – usually in exploratory laparotomy
(opening up abdomen to visualize the contents of the cavity)
- Left paramedian
- Gridiron – for appendectomies
- Transverse
- Pfannensteil (supra pubic) – ‘bikini’ – for caesarean section
- Subcostal – for stones in gallbladder
Rectus Sheath
Anterior layer
E. Nerves and Vessels
In upper ¾; aponeurosis of external oblique and
internal oblique
Fused aponeurosis of internal oblique and
transversalis
Demarcates the lower limit of wall
Rectus Sheath Contents
- Rectus abdominis
- Pyramidalis
- Superior/inferior epigastric vessels
- Lymphatics
- Terminal portions of anterior rami of spinal nerves T7-T12
F. Internal Surface of Anterolateral Abdominal Wall
- Covered with parietal peritoneum
- Peritoneal folds – in infraumbilical surface
- Contains remnants of fetal vessels
5 Umbilical Folds
From apex of urinary bladder to umbilicus; covers
Median fold
medial umbilical ligament (remnant of urachus)
Cover medial umbilical ligaments (remnants of fetal
2 Medial folds
umbilical arteries)
2 Lateral
Cover the inferior epigastric vessels
umbilical folds
Functions of Abdominal Muscles
- Strong, flexible support
- Protects viscera
- Increases abdominal pressure to assist in elimination of gas,
liquid, and solid
- Moves the trunk, maintains posture
- In patients with abdominal pain, the abdominal muscles
provide balance
Group 2
Aguila. Arano. Angeles. Balictar. Escobillo. Pena. Ronquillo. Tagalog. Uy. Yeo. Yu
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BATCH 2014  Anterior Abdominal Wall, Peritoneal Cavity, Diaphragm
III. Peritoneum and Peritoneal Cavity
Peritoneum
- Continuous, glistening, transparent serous membrane
- Innermost
 Parietal - lines the internal surface of the
abdominopelvic wall
 Visceral- invests the viscera (eg. spleen, stomach)
Abdominal Cavity
Peritoneal Fossae
- Depressions lateral to the umbilical folds
- Potential site for hernias
- Lateral inguinal
G. Inguinal Region
- In the inferior part of wall
- Area of weakness in males, due to passage of spermatic cord
through the inguinal canal
Inguinal Canal
- Oblique, inferomedially directed
passage (between superficial and deep
inguinal rings)
- Parallel and superior to medial half of
inguinal ligament
Inguinal Canal Contents
- Spermatic cord in males
- Round ligament of the uterus in
females
- Blood/lymphatic vessels
- Ilioinguinal nerve
Inguinal Canal Openings
- Deep (internal) ring
 Entrance
 Outpouching of transversalis
faschia
 Lateral to inferior epigastric vessels
- Superficial (external) ring
 Exit
 Opening between fibers of external oblique
Inguinal Canal
- Anterior wall – external oblique aponeurosis, with
contributions from internal oblique in lateral part
- Posterior wall – transversalis faschia
Group 2
Peritoneal Cavity
- Potential space between the parietal and visceral layers of
the peritoneum
- Thin layer of peritoneal fluid keeps layers moist
- Fluids keeps viscera to move without friction, especially
during movements of digestion
- In males, completely closed
- In females, potential communication to exterior via uterine
tubes, uterine cavity, vagina
Peritoneal Fluid
- Contains leucocytes, antibodies
Intraperitoneal Organs
- Almost completely covered with visceral peritoneum
- Stomach
Extraperitoneal/Retroperitoneal Organs
- External/posterior to the parietal peritoneum
Peritoneal Vessels and Nerves
- Parietal peritoneum
- Supplied from abdominal wall vessels
- Somatic nerve innervated
- Lymphatics from abdominal wall
Peritonitis
- Inflammation of peritoneum
- Causes pain, increased muscles tone of abdominal muscles
- Muscle guarding
- Acute abdomen
- Involuntary contraction
Aguila. Arano. Angeles. Balictar. Escobillo. Pena. Ronquillo. Tagalog. Uy. Yeo. Yu
Page 3 of 4
BATCH 2014  Anterior Abdominal Wall, Peritoneal Cavity, Diaphragm
Parts of Peritoneum
Double layer of peritoneum reflecting from abdominal
Mesentery wall to enclose all/part of viscera; continuity of
visceral/parietal peritoneum
Peritoneal
Double layer of peritoneum (more limited than, or a…)
ligament
Double-layered sheet of peritoneum from stomach to
Omentum
another abdominal organ; Greater omentum (gastrocolic
ligament)
IV. Diaphragm
Thoracic Diaphragm
- Dome-shaped, musculotendinous partition
- Separates the thoracic cavity from the abdominal cavity
- Descends during inspiration, but only central part moves
- Right and left dome – right dome is higher due to larger right
lobe of liver
- Central tendon – trifoliate structure situated immediately
below the pericardium with which it is partially blended
- Sternal part – attaches to xiphoid process
- Costal part – forms the right and left domes arises from the
inner surfaces of the lower costal cartilages and ribs and
interdigitate with the transversus abdominis
- Aortic hiatus
 Posterior opening
 Aorta, azygos vein, thoracic duct
- Superior surface
 Pericardiocophrenic/musculocophrenic arteries from
internal thoracic
 Superior phrenic arteries from thoracic aorta
- Inferior surface
 Inferior phrenic artery – usually 1st branch of abdominal
aorta
B. Actions of Diaphragm
- Contraction causes dome to move inferiorly
- Abdominal viscera also move inferiorly
A. Diaphragmatic Apertures
- Cava opening – passage of IVC, right phrenic nerve,
lymphatics
- Esophageal hiatus
 For esophagus
 T10 level
 Anterior/posterior vagal trunks, left gastric vessels,
lymphatics
Group 2
Aguila. Arano. Angeles. Balictar. Escobillo. Pena. Ronquillo. Tagalog. Uy. Yeo. Yu
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