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The bladder.
The internal sphincter muscle at the base of the bladder prevents urine from mixing with sperm during ejaculation. This muscle contracts to close off the bladder's exit, ensuring that only semen passes through the urethra. Additionally, the flow of semen from the ejaculatory ducts during ejaculation helps to clear any urine that may be present in the urethra beforehand.
bladder sphincter
Smooth muscle surrounding the bladder pushes urine out of the urethra.
sphincter
The Bladder Wall
The detrusor muscle is the main muscle within the bladder that contracts during urination to help expel urine. It is a smooth muscle that forms a triangular shape at the base of the bladder.
The sphincter muscle closes like a rubber band around the opening of the bladder to prevent urine from leaking out. This muscle is controlled by nerves and can be consciously relaxed or contracted to release or hold urine in the bladder.
Detrusor muscle is found in the urinary bladder.
Urinary bladder mainly contains two types of musces 1. Smooth muscles, forming the wall of the bladder ( Detrusor muscle ) and the internal urethral sphincter ( which controls the flow of urine which is involuntary ), and 2. Skeletal muscle, which forms the external urethral sphicter with which we can control the flow of urine.. ( voluntary control of flow )
The internal urethral sphincter is a smooth muscle located at the neck of the urinary bladder and surrounds the opening of the urethra. It helps in controlling the flow of urine from the bladder to the urethra.