SPONGY URETHRA. TESTES. 601 



Mr. Tyrrell, from the posterior fibres of the detrusor into the tissue of 

 this process. 



The Membranous portion, the narrowest part of the canal, is some- 

 what less than an inch in length. It is situated between the two layers 

 of the deep perineal fascia, and is surrounded by the fan-like expansions 

 of the upper and lower segments of the compressor urethrse muscle 

 which meet at the raphe along its upper and lower surface. It is 

 continuous posteriorly with the prostatic urethra, and anteriorly with the 

 spongy portion of the canal. Its coverings are the mucous membrane, 

 elastic fibrous layer, compressor urethrae muscle, and a partial sheath 

 from the deep perineal fascia. 



The Spongy portion forms the rest of the extent of the canal, and is 

 lodged in the corpus spongiosum from its commencement at the deep 

 perineal fascia to the meatus urinarius. It is narrowest in the body, 

 and becomes dilated at either extremity, posteriorly in the bulb, where 

 it is named the bulbous portion, and anteriorly in the glans penis, 

 where it forms the fossa navicularis. The meatus urinarius is the 

 most constricted part of the canal ; so that a catheter, which will enter 

 that opening, may be passed freely through the whole extent of a 

 normal urethra. Opening into the bulbous portion are two small ex- 

 cretory ducts about three-quarters of an inch in length, which may be 

 traced backwards, between the coats of the urethra and the bulb, to the 

 interval between the two layers of the deep perineal fascia, where 

 they ramify in two small lobulated and somewhat compressed glands 

 of about the size of peas. These are Cowper's glands ; they are 

 situated immediately beneath the membranous portion of the urethra, 

 and are enclosed by the lower segment of the compressor urethrse 

 muscle so as to be subject to muscular compression. Upon the whole 

 of the internal surface of the spongy portion of the urethra, particularly 

 along its upper wall, are numerous small openings or lacunae, which are 

 the apertures of mucous glands situated in the submucous areolar 

 tissue. The openings of these lacunae are directed forwards, and are 

 liable occasionally to intercept the point of a small catheter in its 

 passage into the bladder. At about an inch and a half from the open- 

 ing of the meatus one of these lacunae is generally found much larger 

 than the rest, and is named the lacuna magna. In a preparation of 

 this lacuna, made by Sir Astley Cooper, the extremity of the canal 

 presents several large primary ramifications. 



TESTES. 



The testes are two small glandular organs suspended from the abdo- 

 men by the spermatic cords, and enclosed in an external tegumentary 

 covering, the scrotum. 



The SCROTUM is distinguished into two lateral halves or hemispheres 

 by a rapht, which is continued anteriorly along the under surface of 

 the penis, and posteriorly along the middle line of the perineum to 



