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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] |
Pubis (bone)
In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing ( ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones are each made up of three sections; a superior ramus, an inferior ramus, and a body. Structure The pubic bone is made up of a ''body'', ''superior ramus'', and ''inferior ramus'' (). The left and right coxal bones join at the pubic symphysis. It is covered by a layer of fat – the mons pubis. The pubis is the lower limit of the suprapubic region. In the female, the pubis is anterior to the urethral sponge. Body The body of pubis has: * a superior border or the pubic crest * a pubic tubercle at the lateral end of the pubic crest * three surfaces (anterior, posterior and medial). The body forms the wide, strong, middle and flat part of the pubic bone. The bodies of the left and right pubic bones join at the pubic symphysis. The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somatic Nervous System
The somatic nervous system (SNS), also known as voluntary nervous system, is a part of the peripheral nervous system (PNS) that links brain and spinal cord to skeletal muscles under conscious control, as well as to sensory receptors in the skin. The other part complementary to the somatic nervous system is the autonomic nervous system (ANS). The somatic nervous system consists of nerves carrying afferent nerve fibers, which relay sensation from the body to the central nervous system (CNS), and nerves carrying efferent nerve fibers, which relay motor commands from the CNS to stimulate muscle contraction. Specialized nerve fiber ends called sensory receptors are responsible for detecting information both inside and outside the body. The ''a-'' of ''afferent'' and the ''e-'' of ''efferent'' correspond to the prefixes ''ad-'' (to, toward) and ''ex-'' (out of). Structure There are 43 segments of nerves in the human body. With each segment, there is a pair of sensory and motor n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urinary System
The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, urinary bladder, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of Electrolyte, electrolytes and Metabolite, metabolites, and regulate Acid–base homeostasis, blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the Renal artery, renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, waste (in the form of urine) exits the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled through the urethra during urination. The female and male urinary system are very similar, differin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostatic Urethra
The prostatic urethra, the widest and most dilatable part of the urethra canal, is about 3 cm long. It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form of the canal is spindle-shaped, being wider in the middle than at either extremity, and narrowest below, where it joins the membranous portion. A transverse section of the canal as it lies in the prostate is horse-shoe-shaped, with the convexity directed forward. The keyhole sign, in ultrasound, is associated with a dilated bladder and prostatic urethra. Additional images File:Illu prostate lobes.jpg, Lobes of prostate File:Illu prostate zones.jpg, Zones of prostate File:Illu penis.jpg, Structure of the penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Urethral Sphincter
The internal urethral sphincter is a urethral sphincter muscle which constricts the internal urethral orifice. It is located at the junction of the urethra with the urinary bladder and is continuous with the detrusor muscle, but anatomically and functionally fully independent from it., page 29Preview Amazon It is composed of smooth muscle, so it is under the control of the autonomic nervous system, specifically the sympathetic nervous system. Function This is the primary muscle for maintaining continence of urine, a function shared with the external urethral sphincter which is under voluntary control. It prevents urine leakage as the muscle is tonically contracted via sympathetic fibers traveling through the inferior hypogastric plexus and vesical nervous plexus. Specifically, it is controlled by the hypogastric nerve, predominantly via the alpha-1 adrenergic receptor. During urination, the preganglionic neurons of this sympathetic pathway are inhibited via signals arising in ... [...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] |
Levator Ani
The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the lesser pelvis, and these unite to form the greater part of the pelvic floor. The coccygeus muscle completes the pelvic floor, which is also called the ''pelvic diaphragm''. It supports the viscera in the pelvic cavity, and surrounds the various structures that pass through it. The levator ani is the main pelvic floor muscle and contracts rhythmically during female orgasm, and painfully during vaginismus. Structure The levator ani is made up of 3 parts: * Iliococcygeus muscle * Pubococcygeus muscle * Puborectalis muscle The iliococcygeus arises from the inner side of the ischium (the lower and back part of the hip bone) and from the posterior part of the tendinous arch of the obturator fascia, and is attached to the coccyx and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reticular Formation
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Synapse
In the nervous system, a synapse is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending on the mechanism of signal transmission between neurons. In the case of electrical synapses, neurons are coupled bidirectionally with each other through gap junctions and have a connected cytoplasmic milieu. These types of synapses are known to produce synchronous network activity in the brain, but can also result in complicated, chaotic network level dynamics. Therefore, signal directionality cannot always be defined across electrical synapses. Chemical synapses, on the other hand, communicate through neurotransmitters released from the presynaptic neuron into the synaptic cleft. Upon release, these neurotransmitters bind to specific receptors on the postsynaptic membrane, inducing an electrical or chemical response in the target neuron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Nerve
A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical vertebrae, cervical, thoracic vertebrae, thoracic, lumbar vertebrae, lumbar, sacral vertebrae, sacral and coccygeal vertebrae, coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system. Structure Each spinal nerve is a mixed nerve, formed from the combination of nerve root axon, fibers from its Dorsal root of spinal nerve, dorsal and Ventral root of spinal nerve, ventral roots. The dorsal root is the afferent nerve fiber, afferent sensory root and carries sen ... [...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] |
