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Pontine Micturition Center
In neuroanatomy, the pontine micturition center (PMC, also known as Barrington's nucleus) is a collection of neuronal cell bodies located in the rostral pons in the brainstem involved in the supraspinal regulation of micturition (urination). 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, hypothalamus and periaqueductal gray (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 muscle of the bladder and inhibitory interneurons 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch, and sometimes the diencephalon is included in the brainstem. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating heart and respiratory system, respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. Ten pairs of cranial nerves come from the brainstem. Other roles include the regulation of the central nervous system and the body's sleep cycle. It is also of prime importance in the conveyance of motor and sensory pathways from the rest of the brain to the body, and from the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasympathetic
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulating the body's unconscious actions. The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed-and-breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response. Nerve fibres of the parasympathetic nervous system arise from the central nervous system. Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve. Three spinal nerves in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex Arc
A reflex arc is a neural pathway that controls a reflex. In vertebrates, most sensory neurons synapse in the spinal cord and the signal then travels through it into the brain. This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain. The brain will receive the input while the reflex is being carried out and the analysis of the signal takes place after the reflex action. There are two types: autonomic nervous system, autonomic reflex arc (affecting inner organs) and somatic nervous system, somatic reflex arc (affecting muscles). Autonomic reflexes sometimes involve the spinal cord and some somatic reflexes are mediated more by the brain than the spinal cord. During a somatic reflex, nerve signals travel along the following pathway: # ''Somatic receptors'' in the skin, muscles and tendons # ''Afferent nerve fibers'' carry signals from the somatic receptors to the Posterior horn of spinal cord, posterior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bladder
The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distensible organ that sits on the pelvic floor. The typical adult human bladder will hold between 300 and (10 and ) before the urge to empty occurs, but can hold considerably more. The Latin phrase for "urinary bladder" is ''vesica urinaria'', and the term ''vesical'' or prefix ''vesico-'' appear in connection with associated structures such as vesical veins. The modern Latin word for "bladder" – ''cystis'' – appears in associated terms such as cystitis (inflammation of the bladder). Structure In humans, the bladder is a hollow muscular organ situated at the base of the pelvis. In gross anatomy, the bladder can be divided into a broad (base), a body, an apex, and a neck. The apex (also called the vertex) is directed forward toward th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Sphincter Muscle Of Female Urethra
The external sphincter muscle of the female urethra is a muscle which controls urination in females. The muscle fibers arise on either side from the margin of the inferior ramus of the pubis. They are directed across the pubic arch in front of the urethra, and pass around it to blend with the muscular fibers of the opposite side, between the urethra and vagina. The term "urethrovaginal sphincter" ("sphincter urethrovaginalis") is sometimes used to describe the component adjacent to the vagina. The "compressor urethrae" is also considered a distinct, adjacent muscle by some sources, Function The muscle helps maintain continence of urine along with the internal urethral sphincter which is under control of the autonomic nervous system. The external sphincter muscle prevents urine leakage as the muscle is tonically contracted via somatic fibers that originate in Onuf's nucleus and pass through sacral spinal nerves S2-S4 then the pudendal nerve to synapse on the muscle. Voiding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Sphincter Muscle Of Male Urethra
The external sphincter muscle of the male urethra, also sphincter urethrae membranaceae, sphincter urethrae externus, surrounds the whole length of the membranous urethra, and is enclosed in the fascia of the urogenital diaphragm. Its external fibers arise from the junction of the inferior pubic ramus and ischium to the extent of 1.25 to 2 cm., and from the neighboring fascia. They arch across the front of the urethra and bulbourethral glands, pass around the urethra, and behind it unite with the muscle of the opposite side, by means of a tendinous raphe. Its innermost fibers form a continuous circular investment for the membranous urethra. Function The muscle helps maintain continence of urine along with the internal urethral sphincter which is under control of the autonomic nervous system. The external sphincter muscle prevents urine leakage as the muscle is tonically contracted via somatic fibers that originate in Onuf's nucleus and pass through sacral spinal nerves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanoreceptors
A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system. Vertebrate mechanoreceptors Cutaneous mechanoreceptors Cutaneous mechanoreceptors respond to mechanical stimuli that result from physical interaction, including pressure and vibration. They are located in the skin, like other cutaneous receptors. They are all innervated by Aβ fibers, except the mechanorecepting free nerve endings, which are innervated by Aδ fibers. Cutaneous mechanoreceptors can be categorized by what kind of sensation they perceive, by the rate of adaptation, and by morphology. Furthermore, each has a different receptive field. By sensation * The Slowly Adapting type 1 (SA1) mechanoreceptor, with the Merkel corpuscle end-organ (also known as Merkel discs) detect sustaine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onuf's Nucleus
Onuf's nucleus is a distinct group of neurons located in the ventral part ( lamina IX) of the anterior horn of the sacral region of the human spinal cord involved in the maintenance of micturition and defecatory continence, as well as muscular contraction during orgasm. It contains motor neurons, and is the origin of the pudendal nerve. The sacral region of the spinal cord is the fourth segment (cervical, thoracic, and lumbar being the first three) of vertebrae in the spinal cord which consists of the vertebrae 26-30. While working in New York City in 1899, Bronislaw Onuf-Onufrowicz discovered this group of unique cells and originally identified it as “Group X.” “Group X” was considered distinct by Onufrowicz because the cells were different in size from the surrounding neurons in the anterolateral group, suggesting that they were independent. Structure Onuf's nucleus is a distinct group of neurons located in the ventral part ( lamina IX) of the anterior horn of the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interneurons
Interneurons (also called internuncial neurons, association neurons, connector neurons, or intermediate neurons) are neurons that are not specifically motor neurons or sensory neurons. Interneurons are the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS). They play vital roles in reflexes, neuronal oscillations, and neurogenesis in the adult mammalian brain. Interneurons can be further broken down into two groups: local interneurons and relay interneurons. Local interneurons have short axons and form circuits with nearby neurons to analyze small pieces of information. Relay interneurons have long axons and connect circuits of neurons in one region of the brain with those in other regions. However, interneurons are generally considered to operate mainly within local brain areas. The interaction between interneurons allows the brain to perform complex functions such as learning and decision-making. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 urinary bladder, bladder. The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine. Related are the urethral sphincter muscles which envelop the urethra to control the flow of urine when they contract. Structure The fibers of the detrusor muscle arise from the Posterior (anatomy), posterior surface of the body of pubic bone, body of the pubis in both sexes (musculi pubovesicales), and in the male from the adjacent part of the prostate. These fibers pass, in a more or less wiktionary:longitudinal, longitudinal manner, up the Anatomical terms of location#Superior and inferior, inferior surface of the urinary bladder, bladder, over its Apex of urinary bladder, apex, and then descend along its fundus of the urinary bladder#Fundus, fundus to become atta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 descending pain modulation. It has enkephalin-producing cells that suppress pain. The periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. The ascending pain and temperature fibers of the spinothalamic tract send information to the PAG via the spinomesencephalic pathway (so-named because the fibers originate in the spine and terminate in the PAG, in the mesencephalon or midbrain). This region has been used as the target for brain-stimulating implants in patients with chronic pain. Role in analgesia Stimulation of the periaqueductal gray matter of the midbrain activates enkephalin-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urethral Sphincter
The urethral sphincters are two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are either the external sphincter muscle of male urethra, male or external sphincter muscle of female urethra, female external urethral sphincter and the internal urethral sphincter. When either of these muscles contracts, the urethra is sealed shut. The external urethral sphincter originates at the ischiopubic ramus and inserts into the intermeshing muscle fibers from the other side. It is controlled by the deep perineal branch of the pudendal nerve. Activity in the nerve fibers constricts the urethra. * The internal sphincter muscle of urethra: located at the bladder's inferior end and the urethra's proximal end at the junction of the urethra with the urinary bladder. The internal sphincter is a continuation of the detrusor muscle and is made of smooth muscle, therefore it is under Smooth muscle tissue, involuntary or autonomic nervous system, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
