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Abdominal Wall: Clinical Relevance
Christopher Archer
carcher08@qub.ac.uk • Abdominal incisions
• Anterolateral Abdominal Wall
• Musculature & Rectus Sheath
• Posterior Abdominal Wall
• Neurovasculature supply
• Inguinal Canal
Overview
• Herniation
• Caput Medusa
• MCQsCommon Abdominal Incisions Layers of
Anterolateral
Abdominal
Wall Musculature
• External Oblique – lower 8 ribs to xiphoid process, linea
alba, pubic crest, pubic tubercle & iliac crest.“Rolled-up”
lower portion forms the inguinal ligament.
• Internal Oblique – lumbar fascia, iliac crest & lateral 2/3
of inguinal ligament to lower 3ribs & costal cartilages,
xiphoid process, linea alba & symphysis pubis.
• TransversusAbdominus – lower 6 costal cartilages,
lumbar fascia, iliac crest & lateral 1/3 of inguinal ligament
to xiphoid process, linea alba & symphysis pubis.
th
• RethusAthominus – symphysis pubis & pubic crest to 5 ,
6 & 7 costal cartilages & xiphoid process.Actions:
• External & internal oblique
muscles – compresses abdominal
contents, assists in flexion &
rotation of trunk, assistsin forced
expiration, micturition, defecation
etc.
• Transversus abdominis –
compresses abdominal contents.
• Rectus abdominis – compresses
abdominal contents,flexes
vertebral column & accessory
muscle of expiration. Rectus Sheath
Formed by aponeuroses of the external &
internal obliques& transversus
abdominus, with anterior & posterior
walls.
Contents:
- Rectus abdominis & pyramidalis
muscles
- Anterior rami of lower 6thoracic
nerves
- Superior & inferior epigastric vessels
- Lymph vesselsThe walls of the sheath vary at 3 levels:
Above the costal margin – anterior wall is
the aponeurosis of external oblique only;
posterior wall is 5-7 costal cartilages &
intercostal spaces.
Costalmargin to arcuate line – internal
oblique splitsinto anterior & posterior
laminae,enclosingthe rectus abdominis.
Arcuateline to symphysispubis –
aponeuroses of all 3muscles form anterior
wall, no posterior wall – rectus abdominis
is in contact with transversalis fascia.Posterior Abdominal Wall
th
• Iliopsoas - flexes • Quadratus lumborum – fixes12 rib during
thigh on trunk. inspiration, depresses during forced expiration
& laterally flexes vertebral column. Neurovascular Supply
• Somatic innervation – sharp,
intense,well localized
• Anterior wall innervated by lower 6
thoracic nerves and first lumbar
nerve – iliohypogastric & ilio-
inguinal nerves
• Posterior wall innervated by
anterior rami of lumbar nerves L1-
L3 (psoas major),anterior rami of
subcostal & L1-L4 nerves (Q.L) &
the femoral nerve (iliacus) • Arterial Supply: Above the Umbilicus
Branches of Thoracic aorta– posterior intercostal arteries
10-11& subcostal artery
Branches of Abdominal Aorta – lumbar arteries 1-4 &
inferior phrenic arteries
Branches of Internal Thoracic Artery – superior epigastric &
musculophrenic arteries
Branches of External Iliac Artery - inferior epigastric and
deep circumflexiliac arteries
• Below theUmbilicus:
Branches of Femoral Artery - superficial epigastric,
superficial circumflex iliac, & superficial external pudendal
arteriesVenous Drainage
• Network of veins radiating from
umbilicus
• Drained above into axillary vein via
lateral thoracic vein
• Drained below into femoral vein via
the superficial epigastric & the great
saphenous veins
• Paraumbilical veins form a portal-
systemic venous anastomosis Inguinal Canal
Oblique passage through the anterolateral abdominal wall; parallel and superior to the inguinal ligament.
Approx. 4cm long from the deep inguinal ring, an opening in the transversalis fascia just above the midpoint
of the inguinal ligament, to the superficial inguinal ring,an openingin external oblique aponeurosis just
superior to the pubic tubercle.
Boundaries:
• Anterior – aponeurosis of external
oblique,reinforced by internal oblique
laterally
• Posterior – transversalis fascia
• Roof – transversalis fascia, internal
oblique & transversus abdominis
• Floor – inguinal ligamentContents:
• Spermatic cord in males
• Round ligament in females
• Ilioinguinal nerve
• Genital branch of genitofemoral nerve• Hesselbach’s/Inguinal Triangle: Herniation:
Protrusion of abdominal
weakness/defectiveness inf
the abdominal wall. • Painless lump which may protrude duringcoughing,
straining, or any activity which increases intra-abdominal
Hernia Presentations: pressure
• Patient may describe being able to “push it back in” i.e.,
reduce it
• Investigations = USS/CT scan
• Irreducible hernias represent a greater risk for
strangulation – restriction of arterial supply
• Strangulation considered a medical emergency; patient
often presents with sudden,severe pain, & symptoms of
bowel obstruction such as nausea,vomiting,constipation
etc.
• Requires immediate surgery to relieve the herniaInguinal Hernias – 75% of Abdominal Hernias
• Passes through the inguinal canal i.e.,
the deep and superficial inguinal rings
• Follows the path of the testes during
descent through theprocessus
vaginalis
• Mass is in the spermatic cord & often
found in the scrotum/labia
• Mass is lateral to inferior epigastric
artery
• More prevalent in males (x20)• Passes through area of weakness in
posterior wall of the inguinal canal
• Mass is adjacent to spermatic cord & rarely
protrudes into the scrotum/labia
• Mass is medial to inferior epigastric arteryCaput Medusae:
• Distension of the superficial veins around the umbilicus & the para-umbilical veins
which anastomose with the portal vein due to portal hypertension
• Most commonly caused by liver cirrhosis
• Other causes include portal vein thrombosis, schistosomiasis & Budd Chiari syndromeMCQs: A patient presents with a
• Direct inguinal
painless protruding mass in
his right inguinal region. • Para-umbilical
When you apply pressure to
it, the mass reduces
however when the deep • Indirect inguinal
inguinal ring is covered and
the patient told to cough,
the mass reappears. What is • Femoral
the best description of this
hernia?
• Incisional • Fascia of external oblique
If a surgeon is
performing a left • Rectus abdominis
paramedian incision
below the arcuate
line, what is the last • External oblique muscle
layer which he will
cut through before
reaching the • Fascia of internal oblique muscle
transversalis fascia?
• Transversus abdominis muscle • Subcostal artery, lumbar arteries 1-4, inferior
phrenic artery & external iliac artery
• Superficial epigastric, superficial external
A surgeon is pudendal & deep circumflex iliac arteries
performing a
laparoscopic repair
• Abdominal aorta, external iliac artery &
of an inguinal hernia femoral artery
and asks you what
the arterial supply of • Superficial epigastric, superficial circumflex
this region is. iliac, & superficial external pudendal
arteries
• Superficial epigastric, superficial external
iliac, & superficial internal pudendal arteries • Lanz incision, transversely crosses point2/3 way
to umbilicus from rightASIS
You are asked to perform an
abdominal examination on a
50-year-old woman who • Rutherford-Morrison incision, runs obliquely
inferiorly from 2cm above ASIS
presents with jaundice, RUQ
pain and fever. On your
inspection, you notice a scar • Transverse incision across McBurney’s point
in the right lower quadrant,
the patient informs you this
was from an appendectomy • McBurney incision, runs obliquely through
McBurney’s pointin leftlower quadrant
when she was a child. Whatis
the name and location of the
incision? • Lanz incision, transversely crosses point 2/3 way
from umbilicus to right ASISQuestions?