The dome of the bladder refers to the superior, rounded portion of the urinary bladder. This anatomical structure serves as a reservoir for urine, playing a role in the body’s waste elimination process. It helps maintain bodily fluid balance and health.
Where the Bladder Dome Is and What It’s Made Of
The bladder dome, also known as the apex, is positioned in the lower abdomen, pointing towards the abdominal wall. This hollow, spherical organ is held in place by ligaments, which connect it to other organs and the pelvic bones. In males, the bladder sits between the pubic bone and the rectum, while in females, it rests in front of the vagina and uterus. The dome and posterior surface of the bladder are covered by the peritoneum, a membrane.
The bladder dome is composed of the detrusor muscle, a layer of smooth muscle that surrounds the bladder. This muscular layer allows the bladder to expand and contract. Lining the inner surface of the dome is transitional epithelium, or urothelium. This tissue allows the bladder to stretch and accommodate changes in volume, preventing urine from leaking into the body.
How the Bladder Dome Works
The bladder dome’s structure enables its primary function: storing urine. As the kidneys filter waste from the blood, urine flows through ureters into the bladder. The detrusor muscle and transitional epithelium allow the dome to expand as it fills with urine. An adult bladder can hold between 300 to 600 milliliters (approximately 10 to 20 ounces) of urine.
When the bladder reaches a certain fullness, nerves within the bladder send signals to the brain, indicating the need to urinate. During urination, the detrusor muscle within the dome contracts, pushing urine out of the bladder. Simultaneously, the bladder neck and sphincter muscles relax, allowing urine to exit the bladder and pass through the urethra. This coordinated action ensures efficient and controlled expulsion of urine.
Health Issues Related to the Bladder Dome
The bladder dome, like other parts of the bladder, can be affected by various medical conditions. Overactive bladder (OAB) is a common issue where the detrusor muscle contracts involuntarily, even when the bladder is not completely full. This can lead to sudden, strong urges to urinate, often resulting in urgency incontinence where urine leakage occurs before reaching a restroom.
Bladder cancer often originates in the urothelial lining of the bladder, including the dome. Symptoms like blood in the urine, painful urination, or frequent urination can indicate a bladder issue. Bladder stones, which are clumps of minerals, can also affect the bladder. Paying attention to changes in urination patterns or discomfort can help in early identification of these conditions.