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Topic: Nerve fiber


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In the News (Tue 18 Jun 19)

  
  Axon - Wikipedia, the free encyclopedia
An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.
The longest axons in the human body, for example, are those of the sciatic nerve, which run from the base of the spine to the big toe of each foot.
Along myelinated nerve fibers, gaps in the sheath known as nodes of Ranvier occur at evenly-spaced intervals, enabling an especially rapid mode of electrical impulse propagation called saltation.
en.wikipedia.org /wiki/Nerve_fiber   (506 words)

  
 Glaucoma - Nerve Fiber Layer Analysis - Chelsea Eye   (Site not responding. Last check: 2007-10-31)
The fiber of all the cells travel in the nerve fiber layer of the retina, and exit the eye via the optic nerve.
As these ganglion cells die, the nerve fibers are lost, the nerve fiber layer becomes thinner, and an empty space in the optic nerve called the "cup" of the optic nerve becomes larger and larger until the nerve is essentially gone.
It is this cup in the optic nerve that the ophthalmologist uses to gauge the extent of damage from glaucoma.
www.chelseaeye.com /early_diagnosis.htm   (600 words)

  
 Neurogenetics at UT Health Science Center
We have studied the rise and fall in the number of axons in the optic nerve of fetal and neonatal cats in relation to changes in the ultrastructure of fibers, and in particular, to the characteristics and spatio-temporal distribution of growth cones and necrotic axons.
Fibers are added to the nerve at a rate of approximately 50,000 per day from E28 until E39—the age at which the peak population of 600,000 to 700,000 axons is reached.
To estimate the number of axons in the optic nerve three values were determined: (1) the total area of the nerve in the particular ultrathin section that was photographed, (2) the area of nerve covered by the sample of micrographs, and (3) the number of axons within the area that was sampled.
www.nervenet.org /papers/Cat86.html   (12179 words)

  
 Nerve fiber regrowth
Neuroscientists at CWRU's School of Medicine, examining how nerve cell regrowth is affected by degenerating spinal cord tissue, have published a new study showing tremendous capacity for nerve fiber regeneration from transplanted adult nerve cells in adult spinal cords with large lesions.
When nerve fibers in the spinal cord are severed, they are no longer able to relay signals to other parts of the nervous system.
The segment of the nerve fiber beyond the cut that is no longer connected to the nerve cell dies.
www.cwru.edu /pubs/cnews/1999/8-19/silver.htm   (746 words)

  
 Evaluating the Optic Nerve Head in Glaucoma
Because the nerve fiber layer is thickest in the superior and inferior arcades closest to the disc, this area should be the brightest portion of the view.
In severe cases nerve fiber layer reversal can occur in which the normal pattern of superior and inferior brightness with increasing dimness towards the papillomacular bundle is lost and the papillomacular area becomes the brightest structure.
Nerve fiber layer reversal is associated with thinning of the neural rim and a diffuse depression or constriction of the visual field.
www.opt.pacificu.edu /ce/catalog/web011/course.htm   (3757 words)

  
 Eye Tests > Nerve fiber analyzer -- EyeMDLink.com
The GDx Nerve Fiber Analyzer is an instrument that uses laser to determine the thickness of the nerve fiber layer.
The nerve fiber layer itself is the tissue that the optic nerve is made up of and, therefore, detection of thinning of the nerve fiber layer may be correlated with risk of glaucoma or progression thereof.
However, thinning of the nerve fiber layer isn't always due to glaucoma; other factors such as aging and vessel occlusions may cause thinning of the nerve fiber layer, so the analysis must be interpreted with caution.
www.eyemdlink.com /Test.asp?TestID=20   (163 words)

  
 Nerve Fiber Analysis - Dr Earl W. Nepple Md - West Bend Wisconsin - Ophthalmic Services - Cataract and Refractive ...
Because the nerve fibers are at the back of the eye and are transparent, the nerve fiber layer has traditionally been examined using indirect methods.
These methods include examining the appearance of the structure of the optic nerve where it enters at the back of the eye when the examining physician looks in the eye or by measuring a patient's subjective response to presentation of spots of light, called a visual field.
The nerve fiber layer may then be monitored with subsequent laser scans to determine if treatment is adequate.
www.lasereyesite.com /nerve.html   (296 words)

  
 MUSCLE - NERVE
Since these fibers are fusiform, the region where the nucleus is situated is generally the thickest part of the fiber.
Fascicles of nerve fibers are surrounded by a perineurium.
A myelinated nerve fiber consists of an axon (axis cylinder) evident as a pinkish spot, surrounded by a myelin sheath that has been mostly retained in this preparation (appearing as a slightly bluish ring around the axon).
medocs.ucdavis.edu /CHA/402/labsyl/01/05.htm   (2383 words)

  
 Peripheral Nerve Histology
The next layer of connective tissue which is denser and ensheaths different bundles of nerve fibers is called perineurium (shown dense blue in the slide).
The nerve fibers itself is stained purple/pink and is seen as a cylinder in the center of myelin which has a light orange stain.
In the above photo, the nerve fiber is labeled A (for axon) and the myelin is labeled m.
cellbio.utmb.edu /microanatomy/nerve/peripheral_nerve_histology.htm   (364 words)

  
 Nerve and Nerve Fibers
The longitudinal streaks with a "bubbly" appearance seen throughout this section are myelinated nerve fibers.
The red arrows are pointing to the outer dark border of the nerve fibers.
Nerve Fibers in a longitudinal section have a characteristic wavy look, which you can observe by following the white arrow and looking at the tissue at the curves.
www3.umdnj.edu /histsweb/lab8/lab8nervefibers.html   (525 words)

  
 GDx Nerve Fiber Analyzer
GDx Nerve Fiber Analyzer is a new exam that may help to physicians to detect earlier changes and more sensitive objective changes to individuals who may have or have glaucoma.
Normal Eye: The bright colors represent a thick nerve fiber layer, darker colors depict areas where the nerve fiber layer is thinner.
Glaucoma: The thickness map is dark, indicating thinning of the nerve fiber layer.
www.midwestglaucoma.com /services/gdx.html   (531 words)

  
 Nerve Tissue
Bundles of nerve fibers within the CNS are referred to as tracts, which are analogous to the nerves of the PNS.
One fiber passes centrally into the gray matter of the spinal cord, the other exits through the dorsal root of a spinal nerve.
The neurotransmitter released from the axon terminals of preganglionic nerves is acetylcholine, whereas that released from postganglionic axon terminals is norepinephrine.
anatomy.iupui.edu /courses/histo_D502/D502f02/Nerve/Nerve.htm   (3552 words)

  
 Dimethyl Sulfoxide (DMSO) Blocks Conduction in Peripheral Nerve C Fibers: a Possible Mechanism of Analgesia
Somatic pain is mediated by unmyelinated C type nerve fibers terminating in the skin, muscle and joint capsules.
C fiber responses were identified by their slower conduction velocity, smaller amplitude and higher stimulus threshold compared to A fibers.
A fiber responses at the beginning of the record are distorted because of the high gain (which saturates the signal averager) and slow timebase needed to demonstrate C responses.
www.dmso.org /articles/nerves/nerve_c.htm   (2471 words)

  
 Widespread nerve fiber damage in brains of patients with multiple sclerosis associated with fatigue
CHICAGO — Extensive nerve fiber damage in the brains of patients with multiple sclerosis (MS) is associated with the debilitating fatigue associated with the disease, according to an article in the February issue of The Archives of Neurology, one of the JAMA/Archives journals.
Although the biological causes of fatigue are unknown, some scientists believe the widespread axonal (nerve fiber) damage associated with MS may also be the root cause of the fatigue reported by patients with MS.
Maria Carmela Tartaglia, B.Sc., M.D., of Montreal Neurological Institute and Hospital, Quebec, and colleagues examined the relationship between nerve fiber damage in the brains of patients with MS and fatigue.
www.eurekalert.org /pub_releases/2004-02/jaaj-wnf021204.php   (503 words)

  
 Glaucoma Service Foundation: GDx Nerve Fiber Analyzer Chat Highlights
The nerve fiber layer is important because it is the tissue that the optic nerve is made of.
In theory, a thinning of the nerve fiber layer is bad.
The HRT does measure thickness of the nerve fiber layers, but that is not its primary job.
www.wills-glaucoma.org /supportgroup/chat08232000.html   (1418 words)

  
 Pinched Nerve - What is it?
A nerve cell that lives in the brain or within the spinal cord is called a central nerve, and a nerve that leaves the spine to go into the arms or legs are called peripheral nerves.
These peripheral nerves are actually bundles of millions of nerve fibers that leave the spinal cord and branch to their target muscles to make them move or go to the skin to provide feeling.
Regardless of where the nerve is pinched, in the neck or in the carpal tunnel, the owner of that nerve will often feel similar symptoms of numbness in the hand, because the brain does not know how to tell the difference between the beginning, middle or end of a nerve.
www.spineuniverse.com /displayarticle.php/article232.html   (787 words)

  
 Eye Tests > Optic nerve imaging -- EyeMDLink.com
Imaging of the optic nerve head for patients who have glaucoma, or are being observed for possible glaucoma, has traditionally been completed with optic nerve photography which remains the standard of analysis.
The patient's optic nerve head is photographed at successive visits and the images compared for structural changes consistent with progression of glaucoma.
The Glaucoma-Scope is a device that allows imaging of the optic nerve head using technology that quantitatively determines the cup/disc ratio of the optic nerve head with algorithms for monitoring change in the optic nerve from one visit to the next.
www.eyemdlink.com /Test.asp?TestID=24   (371 words)

  
 eMedicine - Single-Fiber EMG : Article by Donald B Sanders, MD   (Site not responding. Last check: 2007-10-31)
Fiber density is a sensitive means of detecting and quantitating rearrangement of the muscle fiber topography in the motor unit; it is increased in neurogenic conditions but also in some myopathies.
The motor nerve may be stimulated proximally to its entry into the muscle, or individual motor nerve branches may be stimulated within the muscle (Image 3).
The stimulating electrode is inserted into the muscle near an intramuscular nerve fiber, and the recording electrode is inserted distally near muscle fibers innervated by this nerve.
www.emedicine.com /neuro/topic343.htm   (2720 words)

  
 BSL PRO Lesson A03 - CAP: Nerve Conduction
The frog sciatic nerve is essentially a bundle of hundreds of individual nerve fibers (axons and long dendrites) bound by connective tissue.
The actual CAP recording uses the frog sciatic nerve, which is made up of hundreds of individual nerve fibers, each with different diameters, resulting in different impulse propagation rates.
Depending on the length of the nerve, you may need to reposition the "R+" lead such that it is connected to the pin that is closest to the end of the nerve, yet clearly in contact with it.
www.biopac.com /bslprolessons/a03/bslproa03.htm   (2930 words)

  
 Cranial Nerves
The olfactory nerve is composed of axons from the olfactory receptors in the nasal sensory epithelium.
The optic nerve is composed of axons of the ganglion cells in the eye.
It is another pure motor nerve fiber and originates from the abducens nucleus located in the caudal pons at the facial colliculus level.
www.pitt.edu /~anat/Neuro/CranialNerves/CN.htm   (962 words)

  
 Researchers identify molecules that underlie nerve fiber degeneration in multiple sclerosis patients   (Site not responding. Last check: 2007-10-31)
MS is an inflammatory disease of the central nervous system in which myelin, the insulation that surrounds the nerve fibers, is damaged in multiple regions, leaving scars that hinder the relay of nerve signals from the brain to the rest of the body.
There is molecular rebuilding of nerve fibers, relay of nerve signals even in the absence of myelin, and recovery of previously lost functions such as the ability to see or walk, as the disease remits.
However, in progressive forms of the disease, entire lengths of the nerve fibers begin to degenerate, resulting in permanent and irreparable damage, a steady worsening of symptoms and accumulation of disability.
www.news-medical.net /?id=1978   (511 words)

  
 Retinal Nerve Fiber Layer Analysis for the Diagnosis and Management of Glaucoma
POAG is conventionally diagnosed by the presence of 2 of 3 essential factors: characteristic atrophy of the optic nerve on ophthalmoscopy or stereoscopic optic disc photography; characteristic visual field defects on perimetric testing; and increased intraocular pressure (IOP) on tonometry.
The Heidelberg Retinal Tomograph, Nerve Fiber Analyzer, GDx, and Ocular Coherence Tomograph, the 4 main devices used for retinal nerve fiber analysis, have all received final U.S. Food and Drug Administration (FDA) clearance to market through the 510(k) process for the diagnosis and follow-up management of POAG.
Based on the above, retinal nerve fiber layer analysis for the diagnosis or follow-up management of primary open angle glaucoma does not meet the TEC criteria.
www.bcbs.com /tec/vol18/18_07.html   (1489 words)

  
 Study finds nerve damage in previously mysterious chronic pain syndrome
The fact that patients' pain severity is out of proportion to the original injury is a hallmark of the syndrome, and has led many to doubt whether patients' symptoms are caused by physical damage or by a psychological disorder.
The skin biopsies showed that, the density of small-fiber nerve endings in CRPS-I patients was reduced from 25 to 30 percent in the affected areas compared with unaffected areas.
No nerve losses were seen in samples from the control participants, suggesting that the damage was specific to CRPS-I, not to pain in general.
www.eurekalert.org /pub_releases/2006-01/mgh-sfn013006.php   (685 words)

  
 Glaucoma Service Foundation to Prevent Blindness: Retinal Nerve Fiber Layer (RNFL) Analysis in Glaucoma: Neil T. ...
Glaucoma is a multi-factorial optic neuropathy characterized by progressive loss of retinal ganglion cells and their nerve fibers, which leads to characteristic loss of visual function.
Measurement of macular thickness provides an indirect measurement of retinal nerve fiber layer thickness in the macula, since thickness of entire retina is determined.
Measurement by nerve fiber analyzer of retinal nerve fiber layer thickness in normal subjects and patients with ocular hypertension.
www.wills-glaucoma.org /2003symp/choplin.htm   (1649 words)

  
 Noninvasive Monitoring of Diabetes-Induced Cutaneous Nerve Fiber Loss and Hypoalgesia in thy1-YFP Transgenic Mice -- ...
The cutaneous yellowish-green fluorescent fibers in the thy1-YFP mice are nerve fibers
Photomicrographs showing the cutaneous nerve fibers in the skin surface of the leg (A) and the innervation patterns of YFP nerve fibers in abdominal (B), diaphragm (C), and lower-leg (D) muscles.
of nerve fiber as in the case of YFP nerve fibers.
diabetes.diabetesjournals.org /cgi/content/full/54/11/3112   (4105 words)

  
 Arch Neurol -- Abstract: Epidermal Nerve Fiber Density: Normative Reference Range and Diagnostic Efficiency, December ...
The effect of age and gender on epidermal nerve fiber density
Axonal swellings predict the degeneration of epidermal nerve fibers in painful neuropathies
Epidermal nerve innervation in impaired glucose tolerance and diabetes-associated neuropathy
archneur.ama-assn.org /cgi/content/abstract/55/12/1513   (816 words)

  
 Optical Tomography-Measured Retinal Nerve Fiber Layer Thickness in Normal Latinos -- Varma et al. 44 (8): 3369 -- ...
Optical Tomography-Measured Retinal Nerve Fiber Layer Thickness in Normal Latinos -- Varma et al.
Average peripapillary and macular retinal nerve fiber layer thickness in normal Latino eyes by age.
in the number of optic nerve fibers are conflicting.
www.iovs.org /cgi/content/full/44/8/3369   (2872 words)

  
 Miami Project | Supporting Nerve Fiber Therapy
Various studies suggest that applying neurotrophins away from a Schwann cell graft results in reentry of fibers.
As they look to applying this knowledge in future human trials, Miami Project researchers are developing and testing feasible techniques for the delivery of neurotrophins.
Miami Project scientists, Bas Blits, Ph.D., Martin Oudega, Ph.D. and Mary Bartlett Bunge, Ph.D. in collaboration with colleagues in the Netherlands, used viral vectors to produce brain-derived nerve growth factor (BDNF) and neurotrophin-3 (NT-3) within the spinal cord.
www.miamiproject.miami.edu /x549.xml   (281 words)

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