The relationship between the pubo-urethral ligaments and the urogenital diaphragm in the human female.код для вставкиСкачать
The Relationship between the Pubo-urethral Ligaments and the Urogenital Diaphragm in the Human Female PAUL S. MILLEY AND DAVID H. NICHOLS Department of Anatomy and Department of Gynecology and Obstetrics, State University of New York at Buffalo, Buffalo, N e w York 14214 The connective tissue supports of the human female urethra have been investigated in 14 cadavers and 20 fetuses. In all cases the urethra was found to be suspended from the pubic bone by bilaterally symmetrical anterior, posterior and intermediate pubo-urethral ligaments. The anterior and posterior ligaments were formed by reflections of the inferior and superior fascial layers of the urogenital diaphragm. The intermediate ligament represented a fusion of these fascial layers and no transverse perineal ligament was found. It is suggested that the term pubovesical ligament is a misnomer since this band of connective tissue passes from the pubic bone to the urethra and not to the bladder. It is thus analogous to the puboprostatic ligament of the male. An anatomical defect in the pubo-urethral ligaments might be a contributing factor to urinary stress incontinence in the female. ABSTRACT A major contribution to our knowledge of the connective tissue supports of the female urethra has been made by Zacharin (’63, ’68). In his study of the “suspensory mechanism” he described anterior, posterior and intermediate pubo-urethral ligaments. The purpose of this investigation was three-fold. First, we wished to study the connective tissue supports of the adult female urethra to determine the validity of Zacharin’s observations. Secondly, the investigation was aimed at determining the relationship of the urethral supports to other established structures of the pelvis and perineum. Thirdly, the studies were extended to determine the same relationships in the fetus. OBSERVATIONS In every specimen studied the urethra was found to be suspended under the arch of the publis by bilaterally symmetrical dense connective tissue bands which had a small but very firm attachment to the anterior or posterior surface of the pubic bone just lateral to the pubic symphysis. The point of attachment was approximately at the junction of the lower onefifth with the upper four-fifths of the bone. From these points of attachment the bands blended with the surrounding periosteum. In a parasagittal plane both anterior and posterior bands fanned out as they passed from their superior bony attachment inferiorly to attach to the superior and superolateral aspects of the urethra. The anterior and posterior bands were thus MATERIALS AND METHODS joined together under the arch of the pubis Gross dissection was performed on 14 in a parasaggital plane to form an interadult embalmed cadavers of females mediate ligament. This intermediate ligaranging in age from 22 to 91 years. Twenty ment, which fused with the urethra informalin-fixed female fetuses ranging in feriorly, lacked a direct superior bony size from 10 to 33 cm crown rump length attachment. The urethra was thus found were dissected under a Bausch and Lomb to be suspended by a connective tissue stereozoom microscope. After dissection sling throughout its entire length. tissue blocks were removed, dehydrated The anterior band, or anterior puboand embedded in paraffin. Sections cut at urethral ligament, was continuous antero7 I“. were stained with acid orcein and the -Gomori one-step trichrome method. Received Oct. 19, ’70. Accepted N O ~24, . ’70. ANAT. REC., 170: 281-284. 28 1 282 PAUL S. MILLEY AND DAVID H. NICHOLS superiorly with the suspensory ligament of in sagittal sections. Anterior, intermediate the clitoris and shared its pubic attach- and posterior pubo-urethral ligaments were ment. Postero-laterally the posterior pubo- well defined. In the smaller specimens the urethral ligament blended, as described relationship of the pubo-urethral ligaments by Zacharin, with the arcus tendineus of to the urogenital diaphragm could not be determined due to difficulty in dissecting the levator ani. When the arcus tendineus was cut, the very delicate fascia of the diaphragm. however, the posterior pubo-urethral liga- The larger fetuses examined did, however, ment retained an attachment to connective appear to have the same superior contissue inferior to the pelvic diaphragm. tinuity between the layers of the uroCareful dissection combining pelvic and genital diaphragm and the pubo-urethral perineal approaches revealed that the pos- ligaments. Histologic sections showed the puboterior pubo-urethral ligament was in fact a modified reflection of the superior fascia urethral ligaments to consist of dense colof the urogenital diaphragm. Similarly lagen, both smooth and striated muscle, the anterior pubo-urethral ligament was a and elastic fibers. superior extension of the inferior fascia DISCUSSION of the urogenital diaphragm (see fig. 1 ) . The results of this study have confirmed The fascia of the urogenital diaphragm was therefore found to be reflected onto the findings of Zacharin. The major support both the anterior and posterior aspects of between the pubic bone and the bladder the pubic bone to a level more superior and urethra in the female have classically and medial than usually described. The been called the “pubovesical ligaments.” It diaphragm did not appear to meet an- is now clear that this is a misnomer for teriorly to form a transverse perineal liga- the inferior attachments of the ligaments ment as in the male. are to the urethra and should therefore In our study of fetal material the sup- more properly be called the pubo-ure thral port of the urethra appeared to be identical ligaments as suggested by Curtis, Anson with that of the adult cadaver as viewed and McVay (’39). Krantz (’51) also de- Fig. 1 Note continuity between superior and inferior fasciae of urogenital diaphragm ( U . G . D.) and pubo-urethral ligaments ( P . U. L.) Vagina, V; Urethra, U. PUBO-URETHRAL LIGAMENTS AND UROGENITAL DIAPHRAGM scribed heavy fibrous bands arising from the lateral aspect of the female urethra and inserting on the pubic bone on each side. He pointed out their analogy to the puboprostatic ligaments in the male. The term “pubovesical ligaments” is also objectionable because i t refers only to the posterior pubo-urethral ligament; the remaining anterior and intermediate pubourethral portions of the suspensory mechanism generally remaining undescribed. The superior and inferior fascial layers of the urogenital diaphragm are usually described as meeting each other anteriorly to close off the deep perineal space. Diagrams of the urogenital diaphragm seen in full face from below usually show this union as a transverse structure which has been called the transverse perineal ligament. Based on this investigation it is felt that this description is also oversimplified. The lateral attachments of the urogenital diaphragm fascial layers appear to continue more superiorly in the female than is usually described. These superior reflections form the suspensory mechanism of the female urethra, the inferior fascia forming the anterior pubo-urethral ligament, and the superior fascia forming the posterior pubo-urethral ligament. Curtis, Anson and McVay (’39) similarly observed a superior reflection of the superior fascia of the urogenital diaphragm. They described how bilateral bands, formed from this fascia, attached to the pubic bone above and “spread out upon reaching the urethral wall.” The point of junction of the inferior and superior fascial layers of the urogenital diaphragm, rather than forming a transverse ligament, is in fact the intermediate pubo-urethral ligament which is the bottom part of the U-shaped suspensory mechanism of the urethra. The presence of the same general arrangements of urethral support in fetuses 283 indicates that the observed relationships in adult cadavers did not result from obstetrical or postpartum changes. The striated muscle found consistently in the pubo-urethral ligaments may represent a reflection of the external striated muscle of the urethral wall and/or a continuation of the most anterior part of the pubococcygeus muscle. The supports of the female urethra are of great clinical importance to the obstetrician and gynecologist. As Krantz (’51) has pointed out, the urethra and bladder function as a unit that may be likened to a lever system with the urethral supports as a fulcrum. One of the anatomical defects contributing to true urinary stress incontinence in the female could be an inadequacy of the pubo-urethral ligaments. Power (’54) has also pointed out that the integrity of the “pubovesical ligaments” is important for maintenance of continence and the process of micturition. It is hoped that the reexamination of urethral supporting structures will contribute to understanding the pathogenesis of cystocele and urethrocele and suggest ways of improving surgical techniques for correcting such defects. The clinical applications of these anatomical observations will be published elsewhere. LITERATURE CITED Curtis, A. H., B. J. Anson and C. B. McVay 1939 The anatomy of the pelvic and urogenital diaphragms, in relation to urethrocele and cystocele. Surg. Gyn. Ob., 68: 161-166. Krantz, K. E. 1951 The anatomy of the urethra and anterior vaginal wall. Amer. J. Ob. and Gyn., 62: 374-386. Power, R. M. H. 1954 A n anatomical contribution to the problem of continence and incontinence in the female. Amer. J. Ob. and Gyn., 67: 302-314. Zacharin, R. F. 1963 The suspensory mechanism of the female urethra. J. Anat., 97: 423-427. 1968 The anatomic supports of the female urethra. Ob. Gyn., 32: 754-759.