THE CORPUS SPONGIOSUM. 163 



By these vessels blood is carried to the spongy substance of 

 the urethra, which is occasionally distended in the same man- 

 ner that the cavernous bodies of the penis are distended during 

 the erection of that organ. But the cellular structure #f this 

 organ is not so unequivocal as that of the corpora cavernosa ; 



Fig. 165.* 



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

 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 reflection from 

 the b'ase of the bladder, upon the anterior surface of the rectum. 3. The ope- 

 ning 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 vesicee. 5. 

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

 diately behind the figure is the uvula vesicse. The constriction of the bladder at 

 this point is the neck of the bladder. 6. The prostatic portion of the urethra. 

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

 below the urethra, is shown. 8. The isthmus, or third lobe of the prostate ; 

 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 urethra. 

 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 corpus spongio- 

 sum, numerous lacunae are seen. 13. The fossa navicularis. 14. The corpus ca- 

 vernosum, cut somewhat obliquely to the right side,near its lower part. The char- 

 acter of the venous-cellular texture is well shown. 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 ( 17) 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. 



