IN TILE MALE.—The urethra, or uro-sexual canal, is the canal by which the urine, the secre tion of the testes, of the prostate and Cowper's glands, with that of the vesiculm seminales,are discharged. It commences at the opening in the anterior part of the neck of the bladder, and terminates at the extremity of the glans penis. In the beginning of its course it tra verses the prostate gland ; it then perforates the triangular ligament, which is stretched across beneath the arch of the pubis ; and after passing through this it enters the groove between and beneath the corpora cavernosa penis, and is now surrounded by the corpus spongiosum urethrm ; and passing th'rougli the glands, an expansion of the latter body, it ends in a slit-like orifice, the meatus urinarius.
Direction. — The direction of the canal varies according to the state of the penis : thus in the relaxed condition of this organ it presents curves like the italic c procum bent ; if we trace it backwards from the meatus, it will be seen to rise towards the pubis ; thence it descends slightly, and passes beneath the arch of that hone, after which it makes a gentle curve upwards to the neck of the bladder.
When the penis is erect, the urethra is straight for at least three-fourths of its course, that is, whilst it traverses the spongy body ; after which it makes a rather abrupt curve towards the opening into the bladder. In the introduction of the catheter, the surgeon, by drawing the penis forwards and upwards, straightens the anterior three-fourths of the canal, thus approximating its direction to that which it assumes in the erect state of the penis; and now, by careful manipulation, in depressing the handle of the instrument be tween the thighs, to a level with the urethral opening in the triangular ligament, he can, without any difficulty, succeed in passing even a straight catheter into the bladder.
It is important to remark that the anterior three-fourths of the urethra are loose and pendulous, whilst the remainder is fixed to the pubis in a manner presently to be de scribed ; a circumstance to be borne in mind in catheterisation.
The urethra is divided by anatomists into three parts, each presenting characteristic peculiarities. Thus the first part is termed the prostatic portion, because it is surrounded by the prostate gland ; the second is de nominated the membranous portion, because, when deprived of its surrounding structures, it is little more than a simple membrane ; it is also called the muscular part, because it is encircled by muscular fibres ; and the last, being entirely invested by the corpus spon giosum, is designated the spongy portion.
According to a rough measurement, it may be stated that the spongy portion occupies about seven parts, the membranous rather less than one part, and the prostatic rather more than one part of the entire length of the tube.
Length. — The urethra has been frequently measured to ascertain its length and diameter ; and much attention has been devoted to this subject by various observers, with the view to the treatment of strictures and other diseases incidental to this canal. It need scarcely be remarked that the urethra varies at different periods of life, according to the evolution of the generative organs ; and hence it is much shorter in the child than in the adult, and it is well known frequently to undergo a marked elongation in old persons, in consequence of hypertrophy of the pro state gland.
I shall here introduce the measurements in length, as given us by some practical surgeons, whose attention has been especially directed to this subject, observing that the length of the urethra is expressed by the extent to which it can be stretched, by drawing the penis somewhat forcibly forward.
According to Ducarp, it rarely exceeds nine inches in length. Whately examined the urethra in forty-eight subjects of different heights : these he arranged under three heads, viz. tall, middling, and short.