CHAPTER X. 

 Tab. XVII. — the heart. 



Fig. 1. A section of the human heart ; a, a, the superior and 

 inferior vena cava, the veins which convey the blood to the, 5, 

 right auricle ; and thence into, c, the corresponding ventricle ; 

 from this ventricle the blood is impelled through, e, the pul- 

 monary artery into the lungs ; and returning by /,/, the pul- 

 monary veins, it is received into, g, the leji auricle ; it flows 

 next into, h, the left ventricle ; which by its contraction dis- 

 tributes the blood through the general arterial system -.—j, the 

 aorta, the great artery which transmits blood to the different 

 parts of the hoAj, from whence it is returned by veins to the 

 cavace ; k, the tight subclavian ; I, the right carotid arteries, 

 originating from one common trunk ; m, the lejl carotid; n, 

 the left subclai^an ; d, the valves of the right ; i, the valves 

 of the left ventricle. 



Fig. 2. The valves of the right side [tricuspid valves) sep- 

 arated from the heart ; a, a, a, the carnace columnce, or muscu- 

 lar fibres of the valve ; b, b, b, the chordce tendinece, or tendi- 

 nous filaments which are attached to, c, the valves. 



Fig. 3. Exhibits the artery cut open with the form of the 

 semilunar valves. 



Fig. 4. A portion of the artery filled, showing how effect- 

 ually the valves prevent the retrograde motion of the blood 

 in the aorta and pulmonary artery. 



