Fig. 2.

Efferent pathways: Major preganglionic and postganglionic neural pathways from the spinal cord to the lower urinary tract. The sympathetic hypogastric nerve, emerging from the inferior mesenteric ganglion, stimulates urethral smooth muscle. The parasympathetic pelvic nerve, emerging from the pelvic ganglion, stimulates bladder detrusor muscle and inhibits urethral smooth muscle. The somatic pudendal nerve stimulates striated muscle of the EUS. Afferent pathways: Ascending afferent inputs from the spinal cord passes through neurons in the periaqueductal gray (PAG) to upper brain regions and the pontine micturition (PMC). ACh, acetylcholine; NE, norepinephrine; NO, nitric oxide; S₂-S₄, sacral segments of the spinal cord; T₁₁-L₂, thoracolumbar segments of the spinal cord.