Elementary exercises in physiology . e ri^ht is larger than the left and bothare usually engorged with blood. The walls of the auricles are thin. 71 The truncus arteriosus is a cylindrical tube somewliat swollen asit lies upon the auricles. The truncus soon divides into two arches,one passing to the right, the otJlier to the left. Eaoh arch soon splitsinto three vessels, the carotid, for the head, the pulmocutaneous,carrying the venous blood to the lungs and skin to be oxygenated,and the aorta, which curves around to the back to meet its fellowwithwhich it unites to form the descending aorta.
Elementary exercises in physiology . e ri^ht is larger than the left and bothare usually engorged with blood. The walls of the auricles are thin. 71 The truncus arteriosus is a cylindrical tube somewliat swollen asit lies upon the auricles. The truncus soon divides into two arches,one passing to the right, the otJlier to the left. Eaoh arch soon splitsinto three vessels, the carotid, for the head, the pulmocutaneous,carrying the venous blood to the lungs and skin to be oxygenated,and the aorta, which curves around to the back to meet its fellowwithwhich it unites to form the descending aorta. Lift up the ventricleand make out the following structures: The right and the leftsuperior vena cava, bringing back blood from the head and upperextremities; the inferior vena cava, appearing just a;bove the liver;the siniis venosus, (practically a fusion of the venae oavae), thechamber into which the caval veins open. The sinus in turn com-municates with the right auricle. vaqus n«TV«. Oeio| Herve, Sinus- _vcnosuj -A^rr:,r^^\: ^^ T*Urieus v ( Fig. 4. Lateral aspect of the heart, showing its principal parts and thedistribution of the branches of the vagus nerve. Carefully slit the heart lengthwise into ventral and dorsal the ventricle note the comparatively small size of the cavity andthe thick walls; note the two openings in the ventricular cavity—one from the auricles, guarded by auriculo-ventricular valves, theother continuous with the truncus arteriosus; note in the truncus atits base near the ventricle three small semilunar valves, also a longi-tudinal fold or so-called spiral valve. The swollen portion of thetrunicus is known as the pylangium; the distal portion formed bythe fusion of the aortic arches is known as the synangium. 241. Dissection op the Vagus Neevb. Introduce a glass rodinto the frogs throat to distendi the parts. Beginning at the anjgleof the mouth, remove the skin between it and the arm and tym- 72 panum. The projection form
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectphysiology, bookyear1
