THE MALE URETHRA 1235 



membrane, and numerous small glands open on its inner surface. It was called 

 by Weber the uterus masculinus, from its being developed from the united 

 lower ends of the atrophied Miillerian ducts, and therefore homologous with the 

 uterus and vagina in the female. 



The membranous portion (pars membranacea) is the shortest, least dilatable, 

 and, with the exception of the external orifice, the narrowest part of the canal. 

 It extends downward and forward, with a slight anterior concavity, between the 

 apex of the prostate and the bulb of the urethra, perforating the urogenital dia- 

 phragm about 2.5 cm. below and behind the pubic symphysis. The hinder part 

 of the urethral bulb lies in apposition with the inferior fascia of the urogenital 

 diaphragm, but its upper portion diverges somewhat from this fascia : the anterior 

 wall of the membranous urethra is thus prolonged for a short distance in front 

 of the urogenital diaphragm; it measures about 2 cm. in length, while the posterior 

 wall which is between the two fasciae of the diaphragm is only 1.25 cm. long. 



The membranous portion of the urethra is completely surrounded by the fibers 

 of the Sphincter urethrse membranacese. In front of it the deep dorsal vein of 

 the penis enters the pelvis between the transverse ligament of the pelvis and the 

 arcuate pubic ligament ; on either side near its termination are the bulbourethral 

 glands. 



The cavernous portion (pars cavernosa; penile or spongy portion) is the longest 

 part of the urethra, and is contained in the corpus cavernosum urethra?. It is 

 about 15 cm. long, and extends from the termination of the membranous portion 

 to the external urethral orifice. Commencing below the inferior fascia of the 

 urogenital diaphragm it passes forward and upward to the front of the symphysis 

 pubis; and then, in the flaccid condition of the penis, it bends downward and 

 forward. It is narrow, and of uniform size in the body of the penis, measur- 

 ing about 6 mm. in diameter; it is dilated behind, within the bulb, and again 

 anteriorly within the glans penis, where it forms the fossa navicularis urethras. 



The external urethral orifice (orificium urethrce externum; meatus urinarius) is 

 the most contracted part of the urethra; it is a vertical slit, about 6 mm. long, 

 bounded on either side by two small labia. 



The lining membrane of the urethra, especially on the floor of the cavernous 

 portion, presents the orifices of numerous mucous glands and follicles situated 

 in the submucous tissue, and named the urethral glands (Litire). Besides these 

 there are a number of small pit-like recesses, or lacunae, of varying sizes. Their 

 orifices are directed forward, so that they may easily intercept the point of a 

 catheter in its passage along the canal. One of these lacunaB, larger than the rest, 

 is situated on the upper surface of the fossa navicularis; it is called the lacuna 

 magna. The bulbo-urethral glands open into the cavernous portion about 2.5 cm. 

 in front of the inferior fascia of the urogenital diaphragm. 



Structure. The urethra is composed of mucous membrane, supported by a submucous tissue 

 which connects it with the various structures through which it passes. 



The mucous coat forms part of the genito-urinary mucous membrane. It is continuous with 

 the mucous membrane of the bladder, ureters, and kidneys; externally, with the integument 

 covering the glans penis ; and is prolonged into the ducts of the glands which open into the urethra, 

 viz., the bulbo-urethral glands ar.d the prostate; and into the ductus deferentes and vesiculae 

 eeminales, through the ejaculatory ducts. In the cavernous and membranous portions the mucous 

 membrane is arranged in longitudinal folds when the tube is empty. Small papillae are found 

 upon it, near the external urethral orifice; its epithelial lining is of the columnar variety except 

 near the external orifice, where it is squamous and stratified. 



The submucous tissue consists of a vascular erectile layer; outside this is a layer of unstriped 

 muscular fibers, arranged in a circular direction, which separates the mucous membrane and 

 submucous tissue from the tissue of the corpus cavernosum urethra?. 



Congenital defects of the urethra occur occasionally. The one most frequently met with is 



where there is a cleft on the floor of the urethra owing to an arrest of union in the middle line. 



i This is known as kypospadias, and the cleft may vary in extent. The simplest and by far the 



