THE MALE URETHRA 1371 



the valve of Guerin (valvidae fossae navicularis), guarding a recess, the lacuna 

 magna. The urethra opens anteriorly by the meatus urinarius. 



The bulbous portion is a name sometimes given to the posterior part of the spongy 

 portion contained within the bulb. 



The meatus urinarius or external orifice of the urethra (orificium urethrae externum) 

 (Figs. 1119 and 1121) is the most contracted part of the urethra; it is a vertical 

 slit (Fig. 1120), about one-quarter of an inch in length, bounded on each side by 

 a small lip or labium. 



The inner surface of the lining membrane of the urethra, especially on the floor 

 of the spongy portion, presents the orifices of numerous mucous glands (Fig. 1121) 

 situated in the subepithelial tissue, and named the glands of Littre* (glandidae 

 uretkrales). Besides these there are a number of little recesses or follicles, of 

 varying sizes, called lacunae (lacunae ureihrales). Their orifices are directed for- 

 ward, so that they may easily intercept the point of a catheter in its passage along 

 the canal. One of these lacunae, larger than the rest, is situated in the upper sur- 

 face of the fossa navicularis, about half an inch from the orifice; it is called the 

 lacuna magna (Fig. 1121). Into the bulbous portion are found opening the ducts 

 of Cowper's glands. 



Structure. The male urethra is composed of three coats mucous, muscular, and fibrous. 



The mucous coat forms part of the urinogenital 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., Cowper's glands and the prostate gland into the vasa deferentia and the seminal 

 vesicles through the ejaculatory ducts. The mucous membrane is arranged in longitudinal 

 folds when the tube is empty. Small papillae are found upon it near the orifice, and its epithelial 

 lining varies in the different divisions. The prostatic portion is lined by transitional cells, con- 

 tinued from the bladder, the membranous portion by stratified columnar cells, and the penile 

 portion by simple columnar epithelium, except in the /(ma navicularis, where stratified squamous 

 cells are found. The cells rest upon a basement membrane supported by the tunica propria, 

 composed of fibroelastic tissue. In the latter are found diffuse lymphoid tissue and racemose 

 gland.s, the urethra! glands (glands of Littre}. 



The muscular layer is continuous with the muscle of the prostate and bladder, and lies external 

 to the mucous coat. It is composed of nonstriated muscle arranged in an outer layer of circular 

 fibres (stratum circulare) and an inner layer of longitudinal fibres (stratum longitudinale). These 

 layers are prominent in the prostatic urethra, less so in the membranous portion, and ultimately 

 disappear in the spongy part. The longitudinal fibres, when contracted, shorten the urethra 

 and increase its diameter. The circular fibres are in a state of tonic contraction and close the 

 urethra, constituting, apparently, a real sphincter (Zeissl, Zuckerkandl). The so-called sphincter 

 of the urethra, the Accelerator urinae, is a voluntary muscle and is not the real sphincter. Out- 

 side of the muscle layer of the urethra is the tissue of the corpus spongiosum. 



The fibrous coat (tunica fibrosa) consists chiefly of white fibrous tissue supporting the pre- 

 ceding coats. 



Applied Anatomy. The urethra may be ruptured by the patient falling astride of any hard 

 substance and striking his perineum, so that the urethra is crushed against the pubic arch. 

 Bleeding will at once take place from the urethra, and this, together with the bruising in the 

 perineum and the history of the accident, will at once point to the nature of the injury. 



Rupture of the urethra leads to extravasation of urine. In rupture back of the superior layer 

 of the triangular ligament the urine usually follows the rectum and reaches the margin of the 

 anus. Rupture of the membranous part liberates urine between the two layers of the triangular 

 ligament, where it remains until a path of exit is made by suppuration or the surgeon's knife. 

 In rupture superficial to the anterior layer of the ligament the urine passes into the scrotum and 

 may mount up to the abdomen between the symphysis and the pubic spine, between which 

 points the deep layer of the superficial fascia is not attached. It cannot pass to the thigh nor 

 cross the midline, because the fascia is attached to the fascia lata and at the midline. 



The applied anatomy of the urethra is of considerable importance in connection with the 

 passage of instruments into the bladder. Otis was the first to point out that the urethra is 

 capable of great dilatation, so that, excepting through the external meatus, an instrument corre- 

 sponding to 18 English gauge (29 French) can usually be passed without damage. The orifice 

 of the urethra is not so dilatable, and therefore may require slitting, although the introduction 

 of the Oberlander dilator, which is expanded after introduction, renders slitting of the meatus 

 seldom necessary in cases of chronic gonorrhea. A recognition of this dilatability caused Bige- 



