Fig. 33-3. Nerve supply of the urinary bladder and related structures. The preganglionic parasympathetic fibers (interrupted lines) to the smooth muscle (detrusor) of the bladder synapse with ganglion cells in the wall of the organ. Most of the afferent fibers (blue) from the bladder and urethra course in the pelvic splanchnic nerves. A few pain fibers from the bladder ascend in the hypogastric plexuses to the upper lumbar part of the spinal cord. The sympathetic supply is not shown. Pain fibers from the urethra course in the pelvic splanchnic and pudendal nerves. The red lines represent motor fibers to the levator ani and sphincter urethrae. Click for high resolution image.