ANATOMY EN A NUTSHELL. 



243 



aortic opening. The smaller flap lies to the left and behind. The smaller 

 flaps are usually found where the two larger flaps meet. 



4. The chordae tendinae are thicker, stronger, and less numerous, but have 

 a similar attachment as those on the right side 



5. The semilunar valves (aortic) are three in number, a right posterior, a 

 left posterior, and an anterior one. They are larger, thicker, and stronger 

 than those on the right side, but are similar in structure and attachment. Their 

 corpora arantii and lunula are more distinct than those of the pulmonary semi- 

 lunar valves. Their sinuses of valsalva are larger than those on the right side. 

 The right coronary artery arises from the anterior sinus and the left coronary 

 artery arises from the left posterior sinus. 



6. The columns? carnea? are smaller and more numerous than those on the 



PLATE XCVIII. 



ANT. TUBERCLE 



TRANSVERSE 

 PROC. 



fORAUEN FOP 

 VERTEBRAL ARTERY. 



PEDICLE. 



SPINOUS 

 PROC. 



The Fifth Cervical Vertebra. 



right side and are arranged in a similar manner. On the posterior wall and at 

 the apex they are interlaced. The musculi papillares are larger than those on 

 the right side, one of which comes from the anterior wall, the other from the 

 posterior wall. The chorda' tendinae arise from their free ends. 



7. Just under the aortic opening there is a small cavity called the aortic 

 vestibule. 



8. The ventricular septum is thick below but above it becomes thinner and 

 losing its muscular fibers consists only of fibrous tissue covered by endothelium. 



For position of valves of the heart in reference to the chest wall, see Plate 

 XVII. 



The structures of the heart consists of muscular fiber- and fibrous rii gs 

 The muscular structure called myocardium Ls formed from small striated, and 

 quadrangular muscular cells which have nude i joined end to end to form fibers 

 and tend to branch, anastomosing with other cells. Some say the heart Is a 

 voluntary muscle because it has striated fiber-, but l1 is governed by the sym- 

 pathetic nerve thus making it involuntary in action. 



The fibrous rings are stronger on the left side than on the right. 



Thev 



