Female pelvic floor anatomy: the pelvic floor, supporting structures, and pelvic organs

Abstract

The development of novel, less invasive therapies for stress urinary incontinence in women requires a thorough knowledge of the relationship between the pathophysiology of incontinence and anatomy. This article provides a review of the anatomy of the pelvic floor and lower urinary tract. Also discussed is the hammock hypothesis, which describes urethral support within the pelvis and provides an explanation of the continence mechanism.

Figure 1

(A) The diameters of the female minor pelvis (superior aperture): A, sacroiliac joint; B, iliopubic eminence; C and D, middle of pelvic brim; E, sacral promontory; F, pubic symphysis. (B) The female pelvis from above: The sacrospinous ligament extends from the ischial spines to the lateral margins of the sacrum and coccyx anteriorly to the sacrotuberous ligament, which extends from the ischial tuberosity to the coccyx. The sciatic foramina are above and below the sacrospinous ligament and anterior to the sacrotuberous ligament. Reprinted, with permission, from Herschorn S, Carr LK. In: Campbell’s Urology. 2002:1092–1139.

Figure 2

Pelvic diaphragm.

Figure 3

Pelvic floor support (midsagittal section of the pelvis): (A) normal tone in the levator ani with acute anorectal angle and horizontal levator plate; note the normal vaginal axis. (B) With loss of tone in the levator ani, there is change in the vaginal axis, sagging of the levator plate, and enlargement of the urogenital hiatus. Reprinted, with permission, from Herschorn S, Carr LK. In: Campbell’s Urology. 2002:1092–1139.

Figure 4

Three-dimensional reconstructed magnetic resonance image of a 28-year-old healthy woman showing pelvic floor muscles and bones. The keyhole shape indicates normal separation of the vagina and rectum and intact perineal body. Reprinted from Fielding JR et al. AJR Am J Roentgenol. 2000; 174:657–660. Reprinted with permission from the American Journal of Roentgenology.

Figure 5

Muscles of the perineum: (A) On the subject’s right side, the membranous layer of the superficial fascia has been removed (note the cut edge). On the subject’s left side, the symphysis pubis, pubis, part of the ischiopubic ramus, superficial perineal muscles, and inferior fascia of the urogenital diaphragm have been removed to show the deep perineal muscles. (B) Deep perineal muscles are continuous with the sphincter urethrae. Reprinted, with permission, from Salmons S. In: Gray’s Anatomy. 1995:737–900.

Figure 6

The 2 major muscular supporting structures: the upper, with the pelvic diaphragm, and the lower, with the perineal membrane (urogenital diaphragm) anteriorly and anal sphincter posteriorly. Reprinted, with permission, from Herschorn S, Carr LK. In: Campbell’s Urology. 2002:1092–1139.

Figure 7

The hammock hypothesis: the anterior vaginal wall with its attachment to the arcus tendineus of the pelvic fascia forms a hammock under the urethra and bladder neck. Reprinted, with permission, from DeLancey JOL. Am J Obstet Gynecol. 1996;175:311–319.

Figure 8

Cross section of urethral supports below the bladder neck: The urethra is supported by a hammock of anterior vaginal wall suspended to the levators (pubococcygeus muscles) and the fascial attachments (FA) to the tendinous arch of the pelvic fascia. In essence, it is a “double hammock.” Reprinted, with permission, from Herschorn S, Carr LK. In: Campbell’s Urology. 2002:1092–1139.

Figure 9

The cardinal and uterosacral ligaments provide support to the cervix and indirectly to the bladder base. The retropubic, vesicovaginal, and rectovaginal spaces are seen at the level of the cervix. Reprinted, with permission, from Raz S et al. In: Campbell’s Urology. 1998:1059–1094.

Figure 10

(A) Vagina and supportive structures drawn from dissection of a 56-year-old cadaver after hysterectomy: The bladder has been removed above the vesical neck. Paracolpium extends along the lateral wall of vagina. (B) In level I, paracolpium suspends vagina from the lateral pelvic walls. In level II, the vagina is attached to arcus tendineus of pelvic fascia and superior fascia of levator ani muscles. Reprinted, with permission, from DeLancey JOL. Am J Obstet Gynecol. 1992;166:1717–1728.

Figure 11

Urethral anatomy: the urethra has distinct muscular elements associated both within and without to permit its functioning for storage and voiding. Reprinted, with permission, from Strohbehn K, DeLancey JOL. Oper Tech Gynecol Surg. 1997;2:5–16.

Figure 12

Lateral view of the pelvic floor with the urethra, vagina, and fascial tissues transected at the level of the vesical neck, drawn from 3-dimensional reconstruction indicating compression of the urethra by downward force (arrow) against the supportive tissues. Reprinted, with permission, from DeLancey JOL. Am J Obstet Gynecol. 1996;175:311–319.