Architecture of female urethral supporting structures based on undeformed high-resolution sectional anatomical images.

Abstract

Female urinary incontinence mainly relates to damage of female urethra supporting structures, while its anatomy and function specially in which the connective tissue part are still unclear and controversial. We study it based on 4 thin-sectional, high-resolution, transverse sectional anatomical images [Chinese Visible Human (CVH) images] and 10 high-resolution MRI images from volunteers. The female urethral supporting structures and its adjacent structures were segmented and three-dimensional (3D) reconstructed with Amira software. The urethral supporting structures include muscular and connective tissue supporting structures. Muscular supporting structures are composed of levator ani muslce and striated urethral sphincter, the connective tissue supporting structures are composed of anterior vaginal wall, pubovesical muscle, pubovesical ligament, lateral vesical ligament, and tendinous arch of pelvic fascia (TAPF). The anterior vaginal wall includes tight and loose connections between urethral, bladder, and vagina. The lateral vesical ligament connects the proximal part of the urethra to the TAPF. The pubovesical muscle is crescent shaped and continues with the detrusor of the bladder superior and directly connects the TAPF laterally. The TAPF is an obvious fibrous structure that originates at the middle-posterior surface of the pubis, travels onto the parietal pelvic fascia, and inserts posteriorly onto the ischial spine. The anterior vaginal wall, the pubovesical muscle, the lateral vesical ligament, and the TAPF create the "hammock" structure and supplement DeLancey's theory. Its support to the proximal urethra and neck of bladder is crucial to maintain stability and urinary continence during increased abdominal pressure.