ORIGINAL COMMUNICATION Origins and Distribution of Nerves to the Female Urinary Bladder: New Anatomical Findings in the Sex Differences KUMIKO YAMAGUCHI, 1 MAYUMI KOBAYASHI, 1 TOMOYASU KATO, 2 AND KEIICHI AKITA 1 * 1 Unit of Clinical Anatomy, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan 2 Department of Gynecology, National Cancer Center Hospital, Tokyo, Japan The development of nerve-sparing procedures is important in preventing bladder dysfunction following radical hysterectomy. In this study, we dissected 14 halves of 7 female pelvises (age range: 46–86 years; mean age: 74 years) to examine the origins, courses, and distributions of nerve branches to the bladder in females in detail, and 6 halves of 3 male pelvises (age range: 71–85 years, mean age: 78 years) to compare with the female specimens. Nerve branches to the bladder originated mainly from the inferior hypogastric plexus, but independ- ent direct branches running along the ureter from the hypogastric nerve were also distributed particularly to the trigone in all female specimens. We classified these independent branches into four types according to their relationship to the ureter. In males the numbers of the independent branches were small and they were difficult to find. The present observations indicate that nerve distribution patterns to the bladder differ between females and males. In nerve sparing procedures for radical hysterectomy, the area between the ureter and the hypogastric nerve is important. Clin. Anat. 24:880–885, 2011. V V C 2011 Wiley-Liss, Inc. Key words: anatomy; bladder; innervation; ureter; inferior hypogastric plexus; trigone INTRODUCTION Radical hysterectomy has been considered the standard treatment in patients with early stage cervi- cal cancer (Piver et al., 1974, Quinn et al., 2006), but it causes significant morbidity. Bladder dysfunctions, especially urinary incontinence, are the most common long-term complications following radical hysterec- tomy (Forney, 1980; Low et al., 1981, Farquarson et al., 1987; Ralph et al., 1991, Zullo et al., 2003; Benedetti-Panici, 2004; Jackson and Naik, 2006). Uri- nary dysfunction is associated with interruption of the neurons innervating the bladder, the urethra, and the pelvic floor muscles during resection of the anterior, lateral, and posterior parametrium and the vaginal cuff (Zullo et al., 2003). The wide resection of the va- gina with attendant loss of support could be one of the reasons for urinary incontinence which develops de novo or worsens after radical hysterectomy. According to a study using urodynamics and ultraso- nography, a decrease in the urethral pressure could contribute to the pathophysiology of incontinence after radical hysterectomy (Axelsen et al., 2007). Urethral sphincter dysfunction caused by sympathetic denervation is responsible for incontinence (Standring et al., 2005). Accordingly, the distribution of sympa- thetic nerve fibers to the urethra and trigone is of particular importance to urethral sphincter function. Numerous studies have been undertaken on the pelvic sympathetic nerves in males with particular ref- erence to erection, ejaculation, and urinary continence (Whitelaw and Smithwick, 1951; Kihara et al., 1998; *Correspondence to: Keiichi Akita, Unit of Clinical Anatomy, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo, Tokyo 113-8519, Japan. E-mail: akita.fana@tmd.ac.jp Received 7 May 2010; Revised 1 November 2010; Accepted 3 March 2011 Published online 27 April 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ca.21186 V V C 2011 Wiley-Liss, Inc. Clinical Anatomy 24:880–885 (2011)