The external urethral sphincter provides the voluntary conscious control of urination, encircling the membranous urethra as a sleeve of striated muscle that is tonically active to maintain continence. It works with the internal urethral sphincter (smooth muscle) and the levator ani to maintain urethral closure pressure above bladder pressure during filling. Sphincter damage during radical prostatectomy is the primary cause of post-prostatectomy stress urinary incontinence.
| Origin | Perineal membrane (inferior fascia of the urogenital diaphragm) |
|---|---|
| Insertion | Encircles the membranous urethra without true bony insertion |
| Nerve Supply | Pudendal nerve via the perineal branch (S2, S3, S4) |
| Blood Supply | Internal pudendal artery |
| Actions |
|
|---|
The external sphincter must relax coordinately with the detrusor contraction during micturition, failure of this coordination (detrusor-sphincter dyssynergia) in spinal cord injury above the sacral cord produces obstructed voiding with elevated bladder pressures that risk upper urinary tract damage.
Post-prostatectomy incontinence from external sphincter damage affects 5 to 20 percent of men following radical prostatectomy for prostate cancer. Pelvic floor rehabilitation targeting the external sphincter before and after surgery significantly reduces the duration and severity of incontinence. Artificial urinary sphincter (AUS) device is the gold standard treatment for severe post-prostatectomy incontinence.
Not directly assessable by palpation. Function is assessed by urodynamic studies measuring urethral closure pressure during filling and voiding phases.
External sphincter damage during radical prostatectomy producing stress urinary incontinence managed with pelvic floor rehabilitation and artificial urinary sphincter implantation for severe cases.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
