The Pontine micturition center (PMC, also known as Barrington's nucleus) is a collection of

neuronal A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. No ...

cell bodies located in the rostral

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Va ...

in the brainstem involved in the supraspinal regulation of

micturition Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...

. When activated, the PMC relaxes the urethral sphincter allowing for micturition to occur. The PMC coordinates with other brain centers, including the medial frontal cortex,

insular cortex The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes) within each hemisphere of the mammalian b ...

hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...

and

periaqueductal gray The periaqueductal gray (PAG, also known as the central gray) is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for d ...

(PAG). The PAG acts as a relay station for ascending bladder information from the spinal cord and incoming signals from higher brain areas.

Regulation

In humans and other mammals, neurons in the PMC send descending excitatory projections to spinally located parasympathetic neurons controlling the

detrusor The detrusor muscle, also detrusor urinae muscle, muscularis propria of the urinary bladder and (less precise) muscularis propria, is smooth muscle found in the wall of the bladder. The detrusor muscle remains relaxed to allow the bladder to stor ...

muscle of the bladder and inhibitory

interneurons Interneurons (also called internuncial neurons, relay neurons, association neurons, connector neurons, intermediate neurons or local circuit neurons) are neurons that connect two brain regions, i.e. not direct motor neurons or sensory neurons. I ...

regulating Onuf's nucleus. Additionally, the PMC receives ascending input from the level of the lumbosacral spinal cord. During bladder filling, neurons within the PMC are turned off. However, at a critical level of bladder distention the afferent information arising from mechanoreceptors in the detrusor switches the PMC on and enhances its activity. This activation results in relaxation of the

male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...

or female external urethral sphincter and contraction of the bladder. While operating as a spino bulbospinal

reflex arc A reflex arc is a neural pathway that controls a reflex. In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This allows for faster reflex actions to occur by activating spinal motor neurons w ...

, this pattern of activity is also elicited through the conscious desire to urinate.

References

*Fowler CJ, Griffiths D, de Groat WC. (June 9, 2008) "The neural control of micturition." ''Nature Reviews Neuroscience'' (6):453-66 *Kuipers R, Mouton LJ, Holstege G. (January 1, 2006) "Afferent projections to the pontine micturition center in the cat." ''The Journal of Comparative Neurology'' 494(1):36-53 *Sasaki M. (December 5, 2005) "Role of Barrington's nucleus in micturition". ''The Journal of Comparative Neurology'' 5;493(1):21-6 Pons Reflexes {{neuroanatomy-stub