Urinary system - Landmarks (Latin)

Urine enters the cavity of the vesica urinaria through two ostia ureteris located on its posterolateral walls, allowing urine to enter and be stored in the vesica urinaria due to the reflex contraction of the sphincter urethrae internus. When micturition is initiated, the muscular wall of the urinary bladder, known as the m. detrusor vesicae muscle, contracts while the sphincter urethrae internus relaxes, allowing urine to flow through the ostium urethrae internum into the upper part of the urethra. Relaxation of the sphincter urethrae externus allows urine to continue into the distal part of the urethra where it is eliminated into the outside environment through the ostium urethrae externum.