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| Trigone of urinary bladder | |
|---|---|
 trigone of urinary bladder | |
 The interior of bladder. | |
| Details | |
| Identifiers | |
| Latin | trigonum vesicae urinariae |
| TA98 | A08.3.01.024 |
| TA2 | 3421 |
| FMA | 15910 |
| Anatomical terminology | |
Thetrigone of urinary bladder (also known as thevesical trigone) is a smooth triangular region of theurinary bladder formed by the twoureteric orifices and theinternal urethral orifice.[1] Between the ureteric openings, there is a fold of mucous membrane called theinterureteric crest orMercier bar.[2] The trigone lies between the crest or ridge, and theneck of the bladder.[3]
The area is very sensitive to expansion and once stretched to a certain degree, stretch receptors in the urinary bladder signal thebrain of its need to empty. The signals become stronger as the bladder continues to fill.
Embryologically, the trigone of the bladder is derived from the caudal end ofmesonephric ducts, which is ofintermediate mesodermal origin (the rest of the bladder isendodermal). In the female the mesonephric ducts regress, causing the trigone to be less prominent, but still present.
The trigone can become irritated in a condition known astrigonitis resulting from long term use of a catheter, or from infection.[3]
