IN THE VENTRICLES OF THE VERTEBRATE HEART. 
461 
and through them with the auriculo-ventricular tendinous ring, the musculi papillares 
may be said to be continuous at the apex and the base respectively. On some occa- 
sions the musculi papillares spring from the interior of the apex in two fascicular 
bundles, the fibres of each bundle radiating and rapidly increasing in number as the 
apex is receded from ; in others they spring from several smaller fasciculi, the fibres of 
the fasciculi being arranged in two sets and remaining more or less distinct, so that each 
musculus papillaris has a bifid appearance (Plate XII. fig. 15, x,yy'). The musculi 
papillares are principally of use in regulating the spiral action of the bicuspid valve, 
which they do through the instrumentality of the chordae tendinese. They are also 
useful, from projecting into the ventricular cavity, in reducing the blood to a state of 
quiescence during the diastole. During the systole they act as spiral lavers, and scoop 
the blood out of the interior of the ventricle by communicating to it a gliding spiral 
movement. 
Situated between the musculi papillares, and, in fact, occupying the spiral interspaces 
or hollows occasioned by their projecting into the ventricular cavity, are the carnese 
columnse. The carnese columnse, like the musculi papillares, proceed in a spiral nearly 
vertical direction from right to left upwards. They are more developed in some 
instances than in others. In the camel, red deer, and American elk they may be said 
to be altogether wanting (Plate XV. fig. 48). In the lion, leopard, horse, ox, and 
ass they are more or less rudimentary ; while in the mysticetus, armadillo, giraffe, and 
sheep they attain a size which almost entitles them to rank with the musculi papillares 
themselves. In the human heart (Plate XII. fig. 15, z) the carnese columnse consist of 
irregularly shaped, rounded muscular bands, arranged so as to form an intricate network 
— some of the bands being attached at both extremities, others throughout their entire 
extent. A portion of the fibres of the carnese columnse are continuous with the fibres 
of the external layer at the base ; others derive attachment from the fibrous ring sur- 
rounding the aorta, and from the auriculo-ventricular tendinous ring. Running between 
the carnese columnse and the musculi papillares are a series of delicate fibrous stays 
(Plate XII. figs. 13 & 14, r, and Plate XV. figs. 47 & 48, r), which hang loosely in the 
ventricular cavity. They vary in thickness with the size of the heart, and probably 
assist in coordinating the movements of the structures between which they are found. 
The spiral interspaces or hollows occupied by the carnese columnse, to which a passing 
allusion has been made, are two in number, a larger and a smaller. They both extend 
from the extreme apex to the extreme base. The larger groove or interspace proceeds 
from the outward or lateral aspect of the apex , and winds in an upward and inward 
or septal direction, until it reaches the apex of the inner segment of the bicuspid valve , 
where it bifurcates — the one portion conducting to the aortic orifice, with which it com- 
municates, the other to the base of the segment, where it terminates. The smaller 
groove or interspace proceeds from the septal side of the apex , and winds in an upward 
and outward or lateral direction, until it reaches the base of the outer segment of the 
bicuspid valve , where it likewise terminates. 
mdccclxiv. 3 q 
