Central nervous control of micturition and urine storage

Abstract

The micturition reflex is one of the autonomic reflexes, but the release of urine is regulated by voluntary neural mechanisms that involve centers in the brain and spinal cord. The micturition reflex is a bladder-to-bladder contraction reflex for which the reflex center is located in the rostral pontine tegmentum (pontine micturition center: PMC). There are two afferent pathways from the bladder to the brain. One is the dorsal system and the other is the spinothalamic tract. Afferents to the PMC ascend in the spinotegmental tract, which run through the lateral funiculus of the spinal cord. The efferent pathway from the PMC also runs through the lateral funiculus of the spinal cord to inhibit the thoracolumbar sympathetic nucleus and the sacral pudendal nerve nucleus, while promoting the activity of the sacral parasymapathetic nucleus. Inhibition of the sympathetic nucleus and pudendal nerve nucleus induces relaxation of the bladder neck and the external urethral sphincter, respectively. There are two centers that inhibit micturition in the pons, which are the pontine urine storage center and the rostral pontine reticular formation. In the lumbosacral cord, excitatory glutamatergic and inhibitory glycinergic/GABAergic neurons influence both the afferent and efferent limbs of the micturition reflex. The activity of these neurons is affected by the pontine activity. There are various excitatory and inhibitory areas co-existing in the brain, but the brain has an overall inhibitory effect on micturition, and thus maintains continence. For micturition to occur, the cerebrum must abate its inhibitory influence on the PMC.

Chiropractic Care of an 8-Year-Old Girl With Nonorganic, Primary Nocturnal Enuresis: A Case Report

“…The somatic (voluntary) control of the external urethral sphincter (ie, tonic muscle contraction to prevent bladder emptying) originates in ventral horn cells in the sacral spinal cord segments (S2-S4). In addition to the motor supply, there are 3 sets of afferent nerves supplying sensory information from the bladder and urethra, 19 the most important of which, with respect to micturition, are A-delta and C fibers, which convey signals from mechanoreceptors and nociceptors in the bladder wall.…”

Neural Control of the Lower Urinary Tract

“…It is called the L-region, the pontine urine storage center or sometimes the lateral pontine continence center ( Fig. 9) (601). Excitation of this region is believed to tighten the urethral sphincter (70).…”

“…Brain stem-spinal storage mechanisms-Electrical stimulation of the PUSC located ventrolateral to the PMC not only excites the EUS but also inhibits reflex bladder activity, increases bladder capacity and the inhibits the bladder excitatory effect of PMC stimulation (601). Neurons in the region of the PUSC project to the nucleus raphe magnus (NRM) in the medulla which contains neurons that in turn project to the lumbosacral spinal cord.…”

“…Electrical (147, 427, 450, 602) or chemical stimulation (103) in the NRM induces serotonergic inhibition of reflex bladder activity. Thus neurons in the PUSC may activate descending inhibitory pathways to the sacral parasympathetic nucleus (601).…”

Critical evaluation of the anatomical location of the Barrington nucleus: Relevance for deep brain stimulation surgery of pedunculopontine tegmental nucleus

“…This pathway is in turn modulated by higher centres of the cerebral cortex involved in the voluntary control of micturition (Groat and Yoshimura, 2010). In addition, four specific areas of the mammalian neural system are important for the control of micturition and continence: I) the ganglion cells of the bladder wall and the sympathetic (autonomic) and dorsal (sensory) root chains; II) the motor neurons and the sensory interneurons of the spinal cord; III) the caudal brainstem (pontine micturition centre); and IV) the cortical and subcortical areas (Blok, 2002;Sugaya et al, 2005).…”