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The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta (of the thorax). ==Structure== The abdominal aorta begins at the level of the diaphragm, crossing it via the aortic hiatus, technically behind the diaphragm, at the vertebral level of T12. It travels down the posterior wall of the abdomen, anterior to the vertebral column. It thus follows the curvature of the lumbar vertebrae, that is, convex anteriorly. The peak of this convexity is at the level of the third lumbar vertebra (L3). It runs parallel to the inferior vena cava, which is located just to the right of the abdominal aorta, and becomes smaller in diameter as it gives off branches. This is thought to be due to the large size of its principal branches. At the 11th rib, the diameter is 122mm long and 55mm wide and this is because of the constant pressure. The abdominal aorta is clinically divided into 2 segments: #The Paravisceral segment, off which the visceral branches arise #The Infrarenal segment, inferior to the renal arteries and superior to the iliac bifurcation 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「abdominal aorta」の詳細全文を読む スポンサード リンク
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