Fig. 4.

Reflex bladder activation occurs via two reflex pathways. The proximal and middle urethra responds to lower and higher frequency stimuli and evokes bladder contractions via supra-T10 circuitry (a). The supra-T10 circuitry in this path may involve either descending projections from higher levels such as the pontine micturition center or both ascending (dashed line) and descending projections. The middle and distal urethra responds to higher frequency stimuli and evokes bladder contractions via sub-T12 circuitry (b).