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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] |
Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal cord is hollow and contains a structure called the central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system. In humans, the spinal cord is a continuation of the brainstem and anatomically begins at the occipital bone, passing out of the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it tapers to become the cauda equina. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nissl Body
In cellular neuroscience, Nissl bodies (also called Nissl granules, Nissl substance or tigroid substance) are discrete granular structures in neurons that consist of rough endoplasmic reticulum, a collection of parallel, membrane-bound cisternae studded with ribosomes on the cytosolic surface of the membranes. Nissl bodies were named after Franz Nissl, a German neuropathologist who invented the staining method bearing his name ( Nissl staining). The term "Nissl bodies" generally refers to discrete clumps of rough endoplasmic reticulum and free ribosomes in nerve cells. Masses of rough endoplasmic reticulum also occur in some non-neuronal cells, where they are referred to as ergastoplasm, basophilic bodies, or chromophilic substance. While these organelles differ in some ways from Nissl bodies in neurons, large amounts of rough endoplasmic reticulum are generally linked to the copious production of proteins. Staining "Nissl stains" refers to various basic dyes that selectively l ... [...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] |
Synaptic Vesicle
In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters that are exocytosis, released at the chemical synapse, synapse. The release is regulated by a voltage-dependent calcium channel. Vesicle (biology), Vesicles are essential for propagating nerve impulses between neurons and are constantly recreated by the cell (biology), cell. The area in the axon that holds groups of vesicles is an axon terminal or "terminal bouton". Up to 130 vesicles can be released per bouton over a ten-minute period of stimulation at 0.2 Hz. In the visual cortex of the human brain, synaptic vesicles have an average diameter of 39.5 nanometers (nm) with a standard deviation of 5.1 nm. Structure Synaptic vesicles are relatively simple because only a limited number of proteins fit into a sphere of 40 nm diameter. Purified vesicles have a protein:phospholipid ratio of 1:3 with a lipid composition of 40% phosphatidylcholine, 32% phosphatidylethanola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonomic Nervous System
The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, its Myocardial contractility, force of contraction, digestion, respiratory rate, pupillary dilation, pupillary response, Micturition, urination, and Animal sexual behaviour, sexual arousal. The fight-or-flight response, also known as the acute stress response, is set into action by the autonomic nervous system. The autonomic nervous system is regulated by integrated reflexes through the brainstem to the spinal cord and organ (anatomy), organs. Autonomic functions include control of respiration, heart rate, cardiac regulation (the cardiac control center), vasomotor activity (the vasomotor center), and certain reflex, reflex ... [...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] |
Rhabdosphincter
A rhabdosphincter (from Greek ''rhabdos'' meaning "rod") is a sphincter consisting of striated muscle fibres. The muscle is a part of the external urethral sphincter that continues superiorly as a trough-like extension running vertically across the anterior aspect of the prostate The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ... to reach the neck of the bladder. References {{muscle-stub Muscular system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Anal Sphincter
The external anal sphincter (or sphincter ani externus) is an oval tube of skeletal muscle fibers. Distally, it is adherent to the skin surrounding the margin of the anus. It exhibits a resting state of tonical contraction and also contracts during the bulbospongiosus reflex. Anatomy The external anal sphincter is far more substantial than the internal anal sphincter. The proximal portion of external anal sphincter overlaps the internal anal sphincter (which terminates distally a little distance proximal to the anal orifice) superficially; where the two overlap, they are separated by the intervening conjoint longitudinal muscle. Structure Historically, the sphincter was described as consisting of three parts (deep, superficial, and subcutaneous). This is not supported by current anatomical knowledge. Some sources still describe it in two layers, deep (or proximal) and superficial (or distal or subcutaneous). Some of the muscles fibres decussate at the anterior midline and po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejaculation
Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the penis through the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. After forming an erection, many men emit Pre-ejaculate, pre-ejaculatory fluid during stimulation prior to ejaculating. Ejaculation involves involuntary Muscle contraction, contractions of the pelvic floor and is normally linked with orgasm. It is a normal part of male Puberty, human sexual development. Ejaculation can occur spontaneously during sleep (a nocturnal emission or "wet dream") or in rare cases because of prostate, prostatic disease. ''Anejaculation'' is the condition of being unable to ejaculate. ''Painful ejaculation, Dysejaculation'' is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the backward flow of semen from the urethra into the urinary bladder, bladder. Premature ejaculation happens shortly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erection
An erection (clinically: penile erection or penile tumescence) is a Physiology, physiological phenomenon in which the penis becomes firm, engorged, and enlarged. Penile erection is the result of a complex interaction of psychological, neural, vascular, and endocrine factors, and is often associated with sexual arousal, sexual attraction or libido, although erections can also be spontaneous. The shape, angle, and direction of an erection vary considerably between humans. Physiologically, an erection is required for a male to effect penetration or sexual intercourse and is triggered by the parasympathetic division of the autonomic nervous system, causing the levels of nitric oxide (a vasodilation, vasodilator) to rise in the Trabeculae of corpora cavernosa of penis, trabecular artery, arteries and smooth muscle of the penis. The arteries Vasodilation, dilate causing the Corpus cavernosum penis, corpora cavernosa of the penis (and to a lesser extent the corpus spongiosum) to fill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulbospongiosus Muscle
The bulbospongiosus muscles (in older texts bulbocavernosus and, for female muscle, constrictor cunni) are a subgroup of the superficial muscles of the perineum. They have a slightly different origin, insertion and function in males and females. In males, these muscles cover the bulb of the penis, while in females, they cover the vestibular bulbs. In both sexes, they are innervated by the deep or muscular branch of the perineal nerve, which is a branch of the pudendal nerve. Structure In males, the bulbospongiosus is located in the middle line of the perineum, in front of the anus. It consists of two symmetrical parts, united along the median line by a tendinous perineal raphe. It arises from the central tendinous point of the perineum and from the median perineal raphe in front. In females, there is no union, nor a tendinous perineal raphe; the parts are disjoint primarily and arise from the same central tendinous point of the perineum, which is the tendon that is forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
