A manual of anatomy . led the hepatic veins; these open into theinferior vena cava just before this vessel passes through thediaphragm. This peculiar course constitutes the portal circulation. The pulmonary veins are usually five in number, three right andtwo left. These start at the root of the lung and the two left proceeddirectly to the left atrium where they empty their blood. On theright side the veins from the superior and middle lobes of the lungusually unite to form one vessel and this and the vein from the inferiorlobe proceed directly to the left atrium where they empty theirblood. T
A manual of anatomy . led the hepatic veins; these open into theinferior vena cava just before this vessel passes through thediaphragm. This peculiar course constitutes the portal circulation. The pulmonary veins are usually five in number, three right andtwo left. These start at the root of the lung and the two left proceeddirectly to the left atrium where they empty their blood. On theright side the veins from the superior and middle lobes of the lungusually unite to form one vessel and this and the vein from the inferiorlobe proceed directly to the left atrium where they empty theirblood. THE AZYGOS VEINS 249 The azygos veins, three in number, collect the blood from mostof the intercostal spaces and serve to connect the superior andinferior venas cavee. The azygos major {vena azygos major) arises opposite the firstor second lumbar vertebra by a branch from the right lumbars,right renals or inferior vena cava. It passes up the right side ofthe vertebral column, through the aortic orifice in the diaphragm. Fig. 184.—The portal vein and its tributaries. to the fourth thoracic vertebra where it arches over the root of theright lung to empty into the superior vena cava. Its tributariesare the lower ten posterior intercostal veins of the right side, theright superior intercostal vein, the azygos minor veins, the rightbronchial vein and several veins from the esophagus, mediastinumand pericardium. The vena azygos minor inferior {vena hemiazygos) arises in theabdomen by a branch from one of the left lumbar veins or from the 250 THE BLOOD-VASCULAR SYSTEM left renal vein. It enters the thorax through the left crus of thediaphragm and passes upward to the ninth or eighth thoracicvertebra where it passes across to the right and terminates in thevena azygos major. Its tributaries are the lower one or two inter-costals and veins from the esophagus and mediastinum. Major. -
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthumananatomy, bookyea
