2 o PRACTICAL ANATOMY. 



UNIVERSAL USE OF SPHINCTER. 



Musculus sphincter vaginae. Musculus sphincter iridis. 



Musculus sphincter urethrae. Musculus sphincter ilei. 



Musculus sphincter prostatas. Musculus sphincter gulae. 



Musculus sphincter cesophagei. Musculus sphincter vesicae. 

 Musculus sphincter laryngis. 



As the following comparison will show, there is no good reason for confusion 

 of terms and an annoying interchange between orbicular muscles and sphincter 

 muscles. Such is usage. 



Summary of Differences Between Orbiculars and Sphincters : 



Orbicular s. 



1. The orbiculars are supplied by spinal nerves. 



2. The orbiculars are all voluntary. 



3. The orbiculars are all dermal muscles. 



4. The orbiculars are at muco-cutaneous margins. 



5. The orbiculars move rapidly. 



6. The orbiculars have parietal blood-supply. 



7. The orbiculars are very sensitive to pain. 



8. They refer their pain to place of irritation. 



9. They report pain foudroyantly. 



10. Their nerve-supply is somatic never sympathetic. 



11. When lacerated, they repair slowly. 



12. They are synonymous for sphincters in three cases only. 



Sphincters. 



1. Sphincters are supplied by the sympathetic. 



2. They are all involuntary unstriped fibre. 



3. They are not dermals, but viscerals. 



4. They are never at muco-cutaneous areas. 



5. They always move slowly. 



6. They have visceral blood-supply. 



7. They are not very sensitive to pain. 



8. They refer pain to somatic areas. 



9. Their own report of pain is dull and slow. 



10. Their nerve-supply is sympathetic. 



1 1. When lacerated, they repair readily. 



The reader is referred to reflexes along somatic and sympathetic lines in the 

 dissection of the female pelvis. 



TIic ('tents. 



This would seem to be the most fully grown and fully developed structure 

 among the organs having sphincteric openings. Its proper sphincters aie 

 known as the os intcnntm and os cxternum. It complies in every way to eleven 

 points characteristic of sphincters. 



GEOMETRICAL TERMS AND FIGURES. You will have much descriptive usage 

 along mathematical lines. This always aids the memory, for it appeals to the 

 basis of every one's education. 



The axilla has base, apex, angles, and boundaries. 



The neck has roof, floor, boundaries, and triangles. 



Tlic nasal fossa has roof, floor, walls, and openings. 



The orbit has roof, floor, base, apex, angles, and walls. 



