474 COLUMNjE CARNEJE. 



valves a subject of special investigation, and has recorded his obser- 

 vations in a very interesting paper* in the Guy's Hospital Reports. 

 The valves consist, according to Mr. King, of curtains; cards, and 

 columns. The anterior valve or curtain is the largest, and is so 

 placed as to prevent the filling of the pulmonary artery during the 

 distention of the ventricle. The rig/it valve or curtain is of smaller 

 size, and is situated upon 'the right side of the auriculo-ventricular 

 opening. The third valve, or "fixed curtain" is connected by its 

 cords to the septum ventriculorum. .The cords (chordae tendinese) 

 of the anterior curtain are attached, principally, to a long column 

 (columna carnea), which is connected with the " right or thin and 

 yielding wall of the ventricle." From the lower part of this column 

 a transverse muscular band, the "long moderator band" is stretched 

 to the septum ventriculorum or " solid wall" of the ventricle. The 

 right curtain is connected, by means of its cords, partly with the 

 long column, and partly with its own proper column, the second 

 column, which is also attached to the " yielding wall" of the ven- 

 tricle. A third and smaller column is generally connected with the 

 right curtain. The " fixed curtain" is named from its attachment to 

 the " solid wall" of the ventricle, by means of cords only, without 

 fleshy columns. 



From this remarkable arrangement of the valves it follows, that 

 if the right ventricle be over distended, the thin or " yielding wall" 

 will give way, and carry with it the columns of the anterior and 

 right valves. The cords connected with these columns will draw 

 down the edges of the corresponding valves, and produce an open- 

 ing between the curtains, through w r hich the superabundant blood 

 may escape into the auricle., and the ventricle be relieved from 

 over-pressure. This beautiful mechanism is therefore adapted, to 

 fulfil the " function of a safety valve" 



The Columna carnece (fleshy columns) is a name expressive of 

 the appearance of the internal walls of the ventricles, which seem 

 formed of muscular columns interlacing in almost every direction. 

 They are divided into three sets, according to the manner of their 

 connexion. 1. The greater number are attached by the whole of 

 one side, and merely form convexities into the cavity of the ven- 

 tricle. 2. Others are connected by both extremities, being free in 

 the middle. 3. A few (columnse papillares) are attached by one 

 extremity to the walls of the heart, and by the other give insertion 

 to the chordae tendinea3. 



The Semilunar valves, three in number, are situated around the 

 commencement of the pulmonary artery, being formed by a folding 

 of its lining membrane, strengthened by a thin layer of fibrous tissue. 

 They are attached by their convex borders, and free by the con- 

 cave which are directed upwards in the course of the vessel, so that, 

 during the current of the blood along the artery they are pressed 

 against the sides of the cylinder; but if any attempt at regurgitation 



* " Essay on the Safety Valve Function in the Right Ventricle of the Human Heart," 

 by T. W. King. Guy's Hospital Reports, vol. ii. 



