MOTION OF THE HEART AND BLOOD 



function is that of a muscle, to contract and to move 

 something, namely its content of blood. 



As in the muscles themselves, the actions and uses 

 of the heart may be understood from the arrangement 

 of its fibers and the structure of its movable parts. 

 Anatomists generally agree with Galen that the heart 

 is composed of a variety of fibers arranged straight, 

 transversely, and obliquely. But in the boiled heart 

 the fibers are seen to be arranged otherwise. All 

 those in the walls and septum are circular as in a 

 sphincter whereas those in the bands are longitudi- 

 nally oblique." So when all these muscles contract 

 simultaneously the apex is pulled toward the base by 

 the bands and the walls are drawn together in a 

 sphere. The heart is contracted on all sides and the 

 ventricles are compressed. Hence it must be recog- 

 nized that since it acts by contraction, its function is 

 to pump blood into the arteries. 



400 B. C, it describes the auriculo-ventricular and semilunar valves, 

 and the chordae tendinae. Air is said to enter the heart and change 

 the blood. The conception of the heart as a muscle is not usually 

 credited either to Harvey or the Hippocratic writer. It is charac- 

 teristic of Harvey to attempt to fortify his ideas by references to the 

 classical authorities. See Note 3, Chapter II. 



^^ Interesting that Harvey boiled the heart to get a clear picture 

 of its fibrous make-up. The best recent analysis of this subject was 

 made by F. P. Mall (Amer. J. Anat., 2: 211, 191 1). Mall describes 

 a deep and superficial "bulbospiral" and "sinospiral" system of 

 fibers which curve around from the base to the apex of the heart. 

 These form a sling-like support for the circular fibers which are especi- 

 ally thick on the left side. Harvey's description is essentially correct. 

 See W. H. Howell's Physiology, loth Ed., Phila., 1927. 



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