266 THE MECHANICS OF THE HEART 



direction is oblique. Rather numerous on the left side, they form 

 merely a thin superficial layer in the right ventricle. At the apex 

 they again curve upward and are finally inserted in the septimi and 

 adjoining papillary muscles. The inner fibers begin in the apical 

 whorl and extend almost in a straight line toward the base, but it is 

 not quite correct to look upon them merely as continuations of the 

 outer fibers. 



MalP divides the superficial fibers into the bulbospiral and sino- 

 spiral. The former begin at the conus, the left side of the aorta and 



FiQ. 131. — Schema to Show the Course of the Superficial and Deep Fibers of the 

 Bulbospiral and Sinospiral Systems. The Heart is Viewed From the Dorsal Side. 

 BS, superficial bulbospiral system; BS', deep bulbospiral system; SS, superficial 

 spinospiral system; *S*S', deep sinospiral system; C, circular fibers round the conus; 

 C, circular fibers round the base of the aorta and the left ostium; LRV, longitudinal 

 bundle of right ventricle, from membranous septum to right ventricle; IV, interven- 

 tricular or interpapillary layer. (Mall.) 



the left side of the left ostium venosum and pursue a spiral course to 

 the apex, where they enter into the formation of the posterior horn 

 of the vortex. Some of these fibers end in the septum and some in 

 the posterior wall of the left ventricle where they terminate in the 

 basal portion of this papillary muscle. The fibers of the sinospiral 

 system originate from the posterior aspect of the heart in the vicinity 

 of the right venous ostium. They pursue a spiral course to the apex, 

 where they form the anterior horn of the vortex and terminate in the 

 anterior wall of the left ventricle and corresponding papillary muscle. 

 . In addition, Mall recognizes a deep bulbospiral and sinospiral system 

 ^ Am. Jour, of Anatomy, ii, 1911, 211. 



