ABDOMINAL AORTA AND INFERIOR VENA CAVA

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ABDOMINAL AORTA AND INFERIOR VENA CAVA

• By Dr. Mujahid Khan

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Location

• Aorta enters the abdomen through the aortic
  opening of the diaphragm
• The opening lies in front of twelfth thoracic
  vertebra
• It descends behind the peritoneum on the anterior
  surface of the bodies of the lumbar vertebrae

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Location

• On its right side lies the inferior vena cava,
  the cisterna chyli and beginning of the azygos
  vein
• On the left side lies the left sympathetic trunk
• It divides into two common iliac arteries at the
  level of fourth lumbar vertebra

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Branches

• Three anterior visceral branches celiac artery,
  superior and inferior mesenteric arteries
• Three lateral visceral branches suprarenal
  artery, renal artery, testicular or ovarian artery

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Branches

• Five lateral abdominal wall branches the
  inferior phrenic artery and four lumbar arteries
• Three terminal branches two common iliac and the
  median sacral artery

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Common Iliac Arteries

• Right and left common iliac arteries are the
  terminal branches of the aorta
• They arise at the level of fourth lumbar vertebra
• Runs downward and laterally along the medial
  border of the psoas muscle
• Each artery divides into external and internal
  iliac arteries in front of the sacroiliac joint

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External Iliac Artery

• It runs along the medial border of psoas,
  following the pelvic brim
• It gives off the inferior epigastric and deep
  circumflex iliac branches
• The artery enters the thigh by passing under the
  inguinal ligament to become the femoral artery

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Inferior Epigastric Artery

• The inferior epigastric artery arises just above
  the inguinal ligament
• Passes upward and medially along the medial
  margin of the deep inguinal ring
• Enters the rectus sheath behind the rectus
  abdominis muscle

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Deep Circumflex Iliac Artery

• Arises close to the inferior epigastric artery
• Ascends laterally to the anterior superior iliac
  spine and the iliac crest
• Supplies the muscles of the anterior abdominal
  wall

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Internal Iliac Artery

• It passes down into the pelvis in front of the
  sacroiliac joint

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Aortic Aneurisms

• Localized or diffuse dilatations of the abdominal
  part of the aorta usually occur below the origin
  of the renal arteries
• Most result from atherosclerosis which causes
  weakening of the arterial wall
• Occur most commonly in elderly men

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Aortic Aneurisms

• Large aneurysms should be surgically excised and
  replaced with a prosthetic graft
• The bifurcation of the abdominal aorta where the
  lumen suddenly narrows may be a lodging site for
  an embolus from the heart
• Severe ischemia of the lower limbs results

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Obliteration of Abdominal Aorta and Iliac Arteries

• Gradual occlusion of the bifurcation of the
  abdominal aorta produced by atherosclerosis
  causes pain in the legs on walking
• Impotence may occur due to lack of blood in
  internal iliac arteries
• Surgical treatment by thromboendarterectomy or a
  bypass graft should be considered

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Inferior Vena Cava

• It conveys most of the blood from the body below
  the diaphragm to the right atrium of the heart
• It is formed by the union of common iliac veins
  behind the right common iliac artery at the level
  of fifth lumbar vertebra
• It ascends on the right side of the aorta
• Pierces the central tendon of the diaphragm at
  the level of the eighth thoracic vertebra

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Inferior Vena Cava

• It drains into the right atrium of the heart
• Right sympathetic trunk lies behind its right
  margin
• Right ureter lies close to its right border
• The entrance into the lesser sac separates the
  inferior vena cava from the portal vein

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Tributaries

• Two anterior visceral tributaries the hepatic
  veins
• Three lateral visceral tributaries the right
  suprarenal vein, renal veins, right testicular or
  ovarian vein
• Lateral abdominal wall tributaries inferior
  phrenic vein and four lumbar veins
• Three veins of origin two common iliac veins and
  the median sacral vein

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Trauma to IVC

• Injuries to inferior vena cava are commonly
  lethal
• The anatomical inaccessibility of the vessel
  behind the liver, duodenum and mesentery of the
  small intestine and the blocking presence of the
  right costal margin make a surgical approach
  difficult

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Trauma to IVC

• The thin wall of the vena cava makes it prone to
  extensive tears
• Due to the multiple anastomoses of the
  tributaries of IVC, it is impossible in an
  emergency to ligate the vessel
• Most patients have venous congestion of the lower
  limbs

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Compression of IVC

• It is commonly compressed by the enlarged uterus
  during the later stages of pregnancy
• This produces edema of the ankles and feet and
  temporary varicose veins
• Malignant retroperitoneal tumors can cause severe
  compression and eventual blockage of IVC

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Compression of IVC

• This results in the dilatation of the extensive
  anastomoses of the tributaries
• This alternative pathway for the blood to return
  to the right atrium is referred to as the
  caval-caval shunt