External urethral sphincter is the muscle which helps holding in the urine in the bladder.Is this the same muscle which prevents the escape of ejaculate from seminal vesicle into the bladder and helps in the flow of semen from seminal vesicle .
Then why if during TURP we go beyond the veru Monteneum retrograde ejaculation occurs and on injury to external urethral sphincter incontinence occurs??
The verumontanum marks the proximal margin of the external sphincter. If the EUS mechanism is damaged, there will be incontinence.
The contraction of the urethral smooth muscle at the level of the verumontanum is important in prevention of retrograde ejaculation. Retrograde ejaculation occurs because of disruption to the bladder neck mechanism. With retrograde ejaculation, the bladder neck muscle doesn’t tighten properly. As a result, sperm can enter the bladder instead of being ejected out the body through the penis.