fibre(redirected from Fibers)
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Related to Fibers: Textile Fibers, Synthetic fibers, Fibres
fi·ber(fī'bĕr), A slender thread or filament.
- a slender filament, in the form of an element of SCLERENCHYMA in plants, or of COLLAGEN, RETICULIN or ELASTIN in animals.
- dietary fibre (roughage), that part of food that cannot be digested and absorbed to produce energy, and which stimulates activity in the circular muscles of the gut, thus preventing various conditions including constipation.
nerve fibrecomponent of all nerves and their branches in the peripheral nervous system (PNS), and of the tracts in the central nervous system (CNS). The central axontransmits nerve impulses (action potentials) to the nerve terminal in motor (efferent) nerves, or from a receptor to a nerve cell body in sensory (afferent) nerves. Also common to all nerve fibres are an outermost covering (neurilemma) and within that the Schwann cells which are crucial to the regeneration process if a fibre is damaged. In myelinated nerve fibres (including motor nerves to skeletal muscle) there is a fatty myelin sheath between the axon and the neurilemma, interrupted at intervals by the 'nodes of Ranvier'; action potentials 'jump' between these, enabling faster conduction. Each efferent nerve fibre runs from a nerve cell body to terminal branches at a nerve-to-nerve synapse or at an effector organ; each afferent fibre runs from a sensory receptor to a relay site in the CNS.
fibrenerve cell axon and its glial envelope
myelinated fibre nerve axon enveloped by a myelin sheath and Schwann cells
unmyelinated fibre nerve axon lacking the myelin sheath, but enveloped by Schwann cells
arcuate fibre's Axons of the ganglion cells of the retina which are temporal to the optic disc and pass above and below the papillomacular bundle in an arcuate course. Syn. arcuate nerve fibres bundle. See retinal raphe; arcuate scotoma.
cilio-equatorial; cilio-posterior capsular fibre's See Zinn, zonule of.
circular fibre's See ciliary muscle.
felderstruktur muscle fibre's A type of extraocular muscle fibres whose effect is to produce slow, and tonic contraction. They are mainly responsible for maintaining smooth pursuit movements. The fibres are located in the superficial portions of the extraocular muscles and are unique to this type of muscle.
fibrillenstruktur muscle fibre's A type of extraocular muscle fibres whose effect is to produce fast and twitch type of contractions. They are mainly responsible for saccadic eye movements. The fibres are located deep within the extraocular muscles and are the type usually found in skeletal muscles.
Henle's fibre See fibre layer of Henle.
lens fibre's Long, six-sided bands containing few organelles and mostly lacking a nucleus, derived from epithelial cells just within the capsule of the crystalline lens and attached to an anterior and to a posterior suture. New lens fibres are continuously produced throughout life thus contributing to lens growth with age.
longitudinal fibre's See ciliary muscle.
macular fibre's See papillomacular fibres.
medullated nerve fibre's See myelinated nerve fibres.
meridional fibre's See ciliary muscle.
fibre's of Mueller See Mueller's cell.
myelinated nerve fibre's Anomalous congenital extension onto the retina of the myelin sheaths covering the optic nerve fibres. This myelination beyond the lamina cribrosa normally disappears soon after birth. Ophthalmoscopically, it appears as whitish, striated feather-shaped patches which may or may not obscure retinal vessels. Vision in these areas may be reduced, although visual acuity is not affected as the patches are most frequently located adjacent to the optic disc and sometimes in the periphery. The most characteristic sign may be an enlargement of the blind spot. Syn. medullated nerve fibres; opaque nerve fibres. See cribriform plate.
fibre optics See fibre optics.
orbiculo-anterior capsular; orbiculo-posterior capsular fibre's See zonule of Zinn.
papillomacular fibre's Axons of the ganglion cells of the macular region of the retina which enter the temporal portion of the optic disc and travel in the central region of the optic nerve. In the optic chiasma, the temporal macular fibres remain on the same side, while the nasal ones cross to the other side. These fibres make up the papillomacular bundle (Fig. F1).
pupillary fibre's Axons of the optic nerve which branch off from the visual portion of the optic tract, before the lateral geniculate body, to run in the superior brachium towards the pretectal region anterior to the superior colliculus. They mediate the pupillary reflexes. See pretectum; pupil light reflex.
radial fibre's See ciliary muscle.
visual fibre's Axons from the ganglion cells of the retina, making up the optic nerves and optic tracts. They synapse in the lateral geniculate body and then project to the region of the calcarine fissure of the cortex conveying the nervous impulses associated with vision.
zonular fibre's See zonule of Zinn.
fibrillenstruktur muscle fibre's See fibrillenstruktur muscle fibres.
Patient discussion about fibre
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