Which levels constitute the sacral spinal reflex arc required for reflexive erection?

Which levels constitute the sacral spinal reflex arc required for reflexive erection?

• A. C3-C5
• B. L1-L3
• C. T10-T12
• D. S2-S4

Answer: (D)

Reflexive erection is driven by a sacral spinal reflex arc. When the penis is stimulated, sensory input travels to the sacral spinal cord, where the parasympathetic outflow to the pelvic organs is generated. The pelvic splanchnic nerves, which arise from the sacral segments S2 through S4, activate the penile arteries by releasing nitric oxide, causing vasodilation and an erection. Higher or lower spinal levels don’t provide this specific sacral parasympathetic pathway, so they can’t mediate the reflexogenic erection. In short, the sacral levels involved are S2 to S4.

Reflexive erection is driven by a sacral spinal reflex arc. When the penis is stimulated, sensory input travels to the sacral spinal cord, where the parasympathetic outflow to the pelvic organs is generated. The pelvic splanchnic nerves, which arise from the sacral segments S2 through S4, activate the penile arteries by releasing nitric oxide, causing vasodilation and an erection. Higher or lower spinal levels don’t provide this specific sacral parasympathetic pathway, so they can’t mediate the reflexogenic erection. In short, the sacral levels involved are S2 to S4.