600 



MEMBRANOUS URETHRA. 



Fig, 178.< 



wall of the canal ; but, during the action of the detmsor muscle of 

 the bladder, the whole ring is expanded by the longitudinal muscular 

 fibres which are inserted into it ; and the veru is especially drawn 

 downwards by two delicate tendons, which have been traced by 



* A longitudinal section of the bladder, prostate gland, and penis, shewing 

 the urethra. 1. The urachus attached to the upper part of the fundus of the 

 bladder. 2. The recto-vesical fold of peritoneum, at its point of reflexion from 

 the base of the bladder, upon the anterior surface of the rectum. 3. The open- 

 ing of the right ureter. 4. A slight ridge, formed by the muscle of the ureter, 

 and extending from the termination of the ureter to the commencement of the 

 urethra. This ridge forms the lateral boundary of the trigonum vesicae. 5. 

 The commencement of the urethra ; the elevation of mucous membrane imme- 

 diately behind the figure is the uvula vesicae. The constriction of the bladder 

 at this point is the neck of the bladder. 6. The prostatic portion of the ure- 

 thra. 7. The prostate gland ; the difference of thickness of the gland, above 

 and below the urethra, is shewn. 8. The isthmus, or third lobe of the pros- 

 tate ; immediately beneath which the ejaculatory duct is seen passing. 9. The 

 right vesicula seminalis ; the vas deferens is seen to be cut short off, close to its 

 junction with the ejaculatory duct. 10. The membranous portion of the ure- 

 thra 11. Cowper's gland of the right side, with its duct. 12. The bulbous 

 portion of the urethra ; throughout the whole length of the urethra of the cor- 

 pus spongiosum, numerous lacunae are seen. 13. The fossa navicularis. 14. 

 The corpus cavernosum, cut somewhat obliquely to the right side, near its 

 lower part. The character of the venous-cellular texture is well shewn. 15. 

 The right crus penis. 16. Near the upper part of the corpus cavernosum, the 

 section has fallen a little to the left of the middle line ; a portion of the septum 

 pectiniforme is consequently seen. This figure also indicates the thickness of 

 the fibrous investment of the corpus cavernosum, and its abrupt termination at 

 the base of (I/) the glans penis. 18. The lower segment of the glans. 19. 

 The meatus urinarius. 20. The corpus spongiosum. 21. The bulb of the 

 corpus spongiosum. 



