ABDOMINAL AORTA AND INFERIOR VENA CAVA By Dr

ABDOMINAL AORTA AND INFERIOR VENA CAVA By: Dr. Mujahid Khan

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

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

Branches Ø Three anterior visceral branches: celiac artery, superior and inferior mesenteric arteries Ø Three lateral visceral branches: suprarenal artery, testicular or ovarian artery

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

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

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

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

Deep Circumflex Iliac Artery Ø Arises close to the inferior epigastric artery Ø Ascends laterally to the anterior superior iliac spine and the iliac crest Ø Supplies the muscles of the anterior abdominal wall

Internal Iliac Artery Ø It passes down into the pelvis in front of the sacroiliac joint

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

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

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

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

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

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

Trauma to IVC Ø Injuries to inferior vena cava are commonly lethal Ø 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

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

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

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