Role of vesical afferent nerve fibres involved in the control of internal anal sphincter motility.

The neural pathways involved in the interactions between urinary bladder and internal anal sphincter (IAS) were studied in anaesthetized spinal cats. Activation of vesical afferents produced in the IAS a reflex increase in the electrical activity and a reflex inhibition of the excitatory responses evoked by stimulation of one hypogastric nerve. Both reflexes are achieved partly in the lumbar spinal cord and partly within the inferior mesenteric ganglion.