1246 



URETHRA. 



forwards to a short distance beyond the arch 

 of the pubis, and in the natural state is the 

 narrowest part of it, when distended, greatly 

 exceeds the rest of the canal in its dimensions, 

 and forms a large oblong sinus from 1 * to If of 

 an inch in length ; and in its transverse dia- 

 meter at its broadest part, from gths to J-g-ths 

 of an inch, the part of the urethra anterior 

 to it not exceeding ^th 5 f an mcn - The 

 broadest part of this sinus lies directly under 

 the arch of the symphysis pubis. The narrow 

 part of the canal, as seen in these injections, is 

 at the point of union between the prostatic 

 and membranous portions." 



The irregularities in the form of the urethra 

 here noticed do not appear to exist at the 

 earlier periods of life. In a cast of the urethra 

 of a boy 11 years old, made by injecting wax, 

 no inequalities such as those mentioned above 

 in the adult were observable throughout its 

 course, the diameter of the cast, which is 

 nearly cylindrical, measuring pretty uniformly 

 ith of an inch. 



Briggs found the curve of the urethra to 

 commence U inch anterior to the bulb; and 

 from this point to its termination in the 

 bladder, to form an arc of a circle of 3^ inches 

 in diameter, the chord of the arc being 2 

 inches, or rather less than one third of the 

 circumference. In another cast the chord 

 of the segment was found to measure 2 T 8 ^ 

 inches of a circle of 3^ inches in diameter, 

 the inclination of the internal orifice, or en- 

 trance into the bladder, forming an obtuse 

 angle with the general course of the urethra. 



The same surgeon remarks, that in young 

 subjects the posterior portion rises nearly 

 at right angles from the rest of the canal, 

 and consequently makes a much sharper bend ; 

 and that this ascending portion is com- 

 paratively longer than in the adult, as was 

 observed by Camper, who justly attributes 

 the circumstances to the higher position of 

 the bladder in early age. A similar remark 

 was made by Bichat; and the fact is well 

 known to the lithotomist, who, in directing 

 the cutting instrument into the bladder of the 

 child, raises the point by depressing the handle 

 at this important stage of the operation. 



According to Briggs, the most depending 

 part of the curve is at the point where the 

 membranous portion would be intersected by 

 a line drawn through the longitudinal axis of 

 the symphysis pubis to the anus : this would 

 divide the membranous part into two equal 

 parts, and pass through the most dilated part 

 of this portion of the canal* 



I shall now pursue the description of the 

 canal, commencing at that part which leads 

 immediately from the bladder, namely the pro- 

 static portion, observing that this, together 

 with the membranous part, is contained almost 

 wholly within the pelvis, and the two con- 

 stitute therefore the pelvic portion of the 

 urethra, and form the true representative of 

 the female urethra. 



* Briggs, on the Treatment of Strictures of the 

 Urethra by Mechanical Dilatation. 



The prostatic portion traverses the prostate 

 gland at the distance of about two lines from 

 the anterior, four from the posterior, and 

 seven from the lateral surface of the gland. 

 In this respect, however, it varies considerably: 

 thus, in some cases, it is very close to the 

 posterior surface, especially where the isthmus 

 of the prostate is imperfectly developed.* 

 The prostatic portion is from 12 to \5 lines 

 in length, and it commences at the neck 

 of the bladder by a round opening, which is 

 slightly raised ; it then expands to the width 

 of 4 or 5 lines, and gradually contracts 

 itself into the membranous portion. It varies 

 in length and direction in different subjects, 

 and differs materially in these respects ac- 

 cording to age. Lisfranc examined it in eight 

 healthy subjects, and found the diameter of 

 the anterior and posterior portions to vary 

 from 3 to 4 lines, whilst the middle portion 

 measured from 4 to 5% lines. 



Although closely invested by the dense 

 tissue of the prostate and its capsule, this is 

 nevertheless the most dilatable part of the 

 whole urethra, and will readily admit the 

 introduction of the fore-finger. The levatores 

 prostates muscles, together with the pubo- 

 prosiatic ligaments, support it, and attach it to 

 the pubis, and it is compressed by the levatores 

 ani. The general direction of this division 

 of the canal is obliquely downwards ; it pre- 

 sents a slight concavity (the prostatic sinus) 

 at its floor, where it is traversed by the caput 

 gallinagmis, which, running from behind for- 

 wards, divides the sinus into two equal parts. 

 In the prostatic sinus the ducts of the prostate 

 open, assuming a crescentic arrangement 

 around the base of the caput gallinaginis, 

 whilst the vasa ejaculatoria terminate usually 

 on the side of the latter body. 



The description of the urethral orifice of 

 the bladder belongs to the anatomy of this 

 viscus, and to the article BLADDER the reader 

 is referred ; but it is requisite here slightly to 

 allude to it, as it bears materially upon the 

 general direction of this part of the urethra. 

 When viewed from before backwards, the 

 opening will be generally found somewhat 

 raised, so that the floor of the urethra forms 

 a slight depression; and this depression is 

 materially increased in hypertrophy of the 

 prostate, a circumstance always to be remem- 

 bered in the introduction of the catheter in 

 such cases. 



In infancy the direction of the prostatic part 

 is very different from what it is in after life. 

 In consequence of the bladder at this early 

 period being situated higher up, that is, more 

 in the abdomen, the urethra at this part rises 

 more vertically, and thus forms an angle with 

 the membranous portion ; hence, as in the 

 aged, the necessity, in passing a sound or ca- 

 theter, to depress the handle to a considerable 

 extent, and thus to raise the point of the in- 

 strument. As the prostate becomes evolved, 



* Lisfranc mentions an instance where the isth- 

 mus was wholly wanting, and the urethra formed a 

 remarkable pouch at this part. 



