ANATOMY IN A NUTSHELL. 



473 



of the urogenital sinus; that of the female is only exceptionally a part of the 

 clitoris. In man the urethra extends from the bladder to the end of the penis, 

 usually a distance of eight or nine inches. The male urethra has three portions 

 — the prostatic, the membranous, the spongy — the structures and the rela- 

 tions of which are essentially different. Except during the passage of the 

 urine or semen the urethra is a mere transverse cleft or slit with its upper and 

 under surfaces in contact. At the orifice of the urethra, at the end of the penis. 

 the slit is vertical and in the prostatic portion somewhat arched. The pros- 

 tatic portion is one and one-fourth inches long, the membranous three-fourths 

 of an inch long, and the spongy four and one-half inches long. The first and 

 second portions are not subject to any physiological changes such as character- 

 ize the third. 



PLATE CCLV. 



FRONTAL PROC. 



TEMPOROMALAR 

 CANALS. 



LEVATOR 



l.ABU SUP. / 



ZYGOMATICS 'M1N- 



7YC0MATIC PROC. 



ZYG0MAT1CUS MAJ. 



External Surface of Malar Bone. 



The urethra has three coats, mucous, muscular, and erectile. The bulb 

 of the urethra is the posterior enlarged rounded extremity of the corpus spong- 

 iosum of the penis. 



The crista urethra is the crest of the urethra; a longitudinal fold of mucous 

 membrane and subadjacent tissue on the median line of the floor of the pros- 

 tatic urethra, about three-fourths of an inch in length and one-fourth of an 

 inch in height where it is greatest. On the summit open the ejaculatory duct-. 

 It is also called colliculus seminalis, caput galliaginis, and veruinontanum. 



The prostatic sinus is a longitudinal groove in the Hoor of the urethra on 

 each side of the crest, into which the prostatic ducts open. 



The pocularis sinus is a small cul-de-sac, from a quarter to hall' an inch in 

 its greatest diameter, situated at the middle of the highest part of the crest 

 of the urethra. It corresponds with the uterus of the female. Also called 

 prostatic vesicle, utricle, uterus masculinus. The semilunar ducts open on the 

 margins of the sinus pocularis. 



Cowper's glands (Plate (VLXXIX) are a pair of accessory prostatic or 

 urethral glands of lobulated or follicular structure which pour a mucous secre- 



