Bassett Collection of Stereoscopic Images of Human Anatomy

The mucosa has been removed from the left half of the trigone to reveal the very delicate muscle fibers that continue from the longitudinal muscle of the left ureter into the trigone, extending toward the opposite ureter and also toward the urethral orifice. A heavy, sling-like layer of muscle, identified here as the m. pubovesicalis (19), lies alongside the neck of the bladder. Posteriorly its fibers appear continuous with the outer longitudinal layer of muscle of the bladder and with fibers extending upward on the ureter from this layer. Anteriorly it encircles the neck of the bladder and sends some fibers into the puboprostatic ligament.