252 



THE HEART. 



fibro-cartilaginous thickening, the nodulus or corjms Arantii (fig. 173,b,3). 

 Other tendinous fibres, arising from the attached border, run in the 

 valve towards the nodule ; occupying its whole extent, except two narrow 



Fig. 173. — Views of parts of 

 THE Semilunar and Mitral 

 Valves, as seen from within 

 THE Ventricle (Allen Thom- 

 son). 



A, ijortion of the ijulmonaiy 

 artery and wall of the right ven- 

 tricle with one entire segment and 

 two half segments of the valve ; 

 a, half the sinus of Valsalva of 

 the left anterior segment ; b, the 

 same of the posterior segment ; 

 c, the entire right anterior 

 sinus (see fig. 172, I, in which 

 the lettering is the same as in 

 the present figure) ; d, d', inner 

 surface of the ventricle; 1, the 

 attachment of the extremities of 

 the segments to the inner wall 

 of the artery ; 2, the middle 

 of the attached border of the 

 segments ; 3, the middle of the 

 free border (corpus Arantii). 



B, portion of the aorta and wall 

 of the left ventricle with one entire 

 segment and two half segments of 

 the aortic valve, and the right 

 or anterior segment of the mitral 

 valve ; a, half the left posterior 

 segment and sinus of Valsalva ; 

 h, the left anterior ; c, the right 

 posterior sinus of Valsalva and 

 segment entire ; in «, and h, the 

 apertures of the coronary arteries 

 are seen ; d, d', the inner surface 

 of the wall of the ventricle ; 1, 2, 

 and 3, as before ; e, e', the base 

 of the anterior segment of the 

 mitral \'alve ; /, its apex ; between 

 c, and e, and /, the attachment 

 of the branched chordie tendineae 

 to the margin and outer surface of 

 the valve segment ; g, the poste- 

 rior or right principal musculus 

 papillaris ; h, the anterior or left 

 principal musculus papillaris : the 

 cut chords tendinoK are those 

 which belong to the posterior 

 segment and the small or inter- 

 mediate segments. 



lunated portions, one on each side, adjoining the free margin of the 

 valve. These parts, which are named lunulas (fig. 173, B), are 

 therefore thinner than the rest. There is also a strengthening 

 fibrous cord surrounding the attached border of each valve. The wall 

 both of the aorta and pulmonary artery is bulged out opposite each 

 semilunar flap : these bulgiugs are known as the sinuses of Valsalva. 

 In the aorta these are situated one anteriorly and two posteriorly (right 



