188 CIRCULATORY SYSTEM. 



one side to the other; others contribute to the mechanism of the 

 valvular apparatus between it and the right auricle; but the 

 greater portion is employed in forming a complicated reticular 

 texture over the internal face of the ventricle. Those connected 

 with the valve vary from four to eight in number: they are 

 rounded, of different lengths and sizes, and detach from their 

 projecting extremities several small rounded tendinous chords, 

 (chorda tendine,} which are inserted into the floating edge of 

 the valve. These chords form an intertexture among them- 

 selves. 



The Valve, between the ventricle and the auricle, consists 

 in a duplicature of the lining membrane of the ventricle, arising 

 uninterruptedly from around the ostium venosum, at the left 

 margin, which is there somewhat tendinous. This valve is 

 called the Tricuspid, (Valvula Tricuspis, Triglochis,} because 

 its loose margin is divided into three points or processes. One 

 of these points, which is at the anterior external margin of the 

 orifice, is much larger than the other two and more distinct in 

 its boundaries. The edges of these processes form a sort of re- 

 ticulated work along with the adjoining ends of the tendinous 

 chords : by this arrangement they are always^ kept expanded 

 and in the cavity of the ventricle. 



The opening for the pulmonary artery is placed above the 

 ostium venosum; at this point, the cavity of the ventricle, in- 

 stead of being reticulated, is made smooth, for the more ready 

 transmission of blood. The orifice of the pulmonary artery is 

 round, and about twelve lines in diameter; it is furnished with 

 three valves, called from their shape Semi-lunar or Sigmoid. 

 Each valve is a semicircular plane, formed from the lining 

 membrane of the artery, and attached to the latter by its semi- 

 circumference. The diameter of the plane is loose, and, instead 

 of being straight, has each semi-diameter of a curved or fes- 

 tooned shape: in the centre of its edge is a small cartilaginous 

 body, the Corpusculum Aurantii, which, when the valve is 

 thrown down by the reaction of the artery, comes in contact 

 with the corresponding bodies of the other valves, so that they 

 serve as mutual abutments. The Corpusculum is sometimes 

 scarcely discernible. Between the outer face of each valve 

 and the artery there is a pouch, attended with a slight dila- 

 tation of the artery, and called the Sinus Valsalvas. Between 



