| cone down | To narrow a beam of X-rays to a region of interest using a collimator or cone; colloq., to delimit one's attention or activities. (05 Mar 2000) |
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| cone dystrophy | A retinal abnormality in which colour perception is severely deficient and typical changes occur in electroretinogram. See: achromatopsia. Synonym: cone degeneration. (05 Mar 2000) |
| cone granule | Nucleus of a retinal cell connecting with one of the cones. (05 Mar 2000) |
| cone of light | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |
| cone vision | Vision when the eye is light-adapted. See: light adaptation, light-adapted eye. Synonym: cone vision, photopia. (05 Mar 2000) |
| muscle fibre | <pathology> Component of a skeletal muscle comprising a single syncytial cell that contains myofibrils. Any of the cells of skeletal or cardiac muscle tissue. Skeletal muscle fibres are cylindrical multinucleate cells containing contracting myofibrils, across which run transverse striations, enclosed in a sarcolemma. Cardiac muscle fibres contain one or sometimes two nuclei and myofibrils and are separated from one another by an intercalated disk; although striated, cardiac fibres branch to form an interlacing network. 2. fast-twitch muscles. Skeletal muscle fibres having high myofibrillar atpase activity, high glycolytic enzyme activities, and an intermediate glycogen content which produce a fast twitch. There are two types. Fast fatigable fibres, also called white fibres, have a low myoglobin content, and a small mitochondrial content, and fatigue rapidly due to their limited glycogen content and low capacity for oxidative metabolism. Fast fatigue-resistant fibres, also called red fibres, have a large mitochondrial content and a high myoglobin content, related to their resistance to fatigue. 3. slow-twitch muscles. Skeletal muscle fibres having low myofibrillar atpase activity, low glycogen content, and high myoglobin content, high mitochondrial oxidative enzyme activities, and an intermediate mitochondrial content which produce a slow twitch and are fatigue-resistant. (12 Dec 1998) |
| pole fibre | <cell biology> Microtubules inserted into the pole regions of the mitotic spindle (each pole is the product of the division of the centrioles and constitutes a microtubule organising centre. (18 Nov 1997) |
| Politzer's luminous cone | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |
| corticobulbar fibre | <physiology> Nerve fibre's projecting from the motor and somatic sensory cortex to the rhombencephalon. Included in this corticofugal fibre system are corticoreticular fibre's terminating in the reticular formation of the rhombencephalon, and corticonuclear fibre's to the motor nuclei innervating the musculature of the face, tongue, and jaws, and to some fibre's of the rhombencephalic sensory relay nuclei. They terminate directly on some motor cranial nerve nuclei, in the reticular formation, and on sensory relay nuclei, such as the cuneate nucleus and gracile nucleus and the spinal trigeminal nucleus. See: corticobulbar tract. (05 Mar 2000) |
| myelinated nerve fibre | An axon enveloped by a myelin sheath formed by oligodendroglia cells (in brain and spinal cord) or Schwann cells (in peripheral nerves). Synonym: medullated nerve fibre. (05 Mar 2000) |
| corticonuclear fibre | <physiology> Descriptive term connotating fibres from a cortical structure (cerebral or cerebellar) passing to subcortical cell groups; fibres comprising the tractus corticobulbaris; cerebellar corticonuclear fibres (Purkinje cell axons to the cerebellar nuclei). Synonym: fibrae corticonucleares. (05 Mar 2000) |
| corticopontine fibre | <physiology> The fibres that compose the corticopontine tract. Synonym: fibrae corticopontinae. (05 Mar 2000) |
| corticoreticular fibre | <physiology> Corticofugal fibres distributed to the reticular formation of the mesencephalon and rhombencephalon. See: corticobulbar fibres. Synonym: fibrae corticoreticulares. (05 Mar 2000) |
| corticorubral fibre | <physiology> Nerve fibres projecting from the cerebral cortex (primarily precentral and premotor regions) to the red nucleus of the midbrain. (05 Mar 2000) |
| cotton-fibre embolism | Embolism by cotton fibres from sterile gauze used in intravenous medication or transfusion; may form as foreign body granulomas in small pulmonary arteries. (05 Mar 2000) |