456 STANHOPE BAYNE-JONES 



pass thr()uj2;h the ro^ion of the iiiuuilus iihrosus at the atrio- 

 ^'entl•icllhll• junction. These small arteries to the valves are not 

 derived from the vessels which supply the auricular musculature, 

 but are distinct bran.ches from the annular arteries passing di- 

 rectly into the valves. The general distribution of these vessels 

 is shown by figure 1 , which is a photograph of the mitral valves 

 of a woman, aged 21, who died after an operation for exoph- 

 thalmic goitre. Autopsy No. 4609. Figure 2 is a drawing of 

 these vessels, made directly from the photograph of the speci- 

 men. The chief arteries to the valve branch from the annular 

 artery at widely separated intervals. These points of entrance 

 are almost directly above the papillary muscles, and the vessels 

 pass down the valve in the thickened portion above the insertions 

 of the chordae tendineae. During this downward course, the 

 arteries give off small lateral branches which ramify as delicate 

 arterioles in the upper third of the membranous portion of the 

 valve. When the thickened area of the line of closure of the 

 valve is reached, the arteries undergo multiple branching, form- 

 ing tufts of vessels in this region (fig. 3). From the terminal 

 arterioles many small vessels anastomose, almost forming glom- 

 erular tufts and loops. In this region the capillaries form abun- 

 dant anastomoses. Only occasional strands of small vessels 

 pass from the line of closure to the free margin of the valves. 

 No vessels were found passing from the valves to the chordae 

 tendinae. 



In the upper portions of the valves distinct differences be- 

 tween the vessels may be seen, differentiating arteries from veins. 

 The arteries have irregular edges, with the lumen constricted in 

 some places and expanded in others. A definite constriction 

 occurs wherever the artery branches. The veins, on the other 

 hand, have a smooth contour, and are not so deeply colored by 

 the injection. These features are shown in figure 4, which is a 

 composite drawing made by Mr. Max Brodel, representing in a 

 semidiagrammatic manner the completely injected regions of sev- 

 eral specimens. 



Chordae tendineae. In the human heart, the vascularity of 

 these structures is slight. The arteries are derived from the 



