| middle gray layer of superior colliculus | See: gray layer of superior colliculus. Molecular layer, term applied to any layer of brain tissue that contains few nerve-cell bodies and is composed largely of terminal arborizations of dendrites and axons; notable examples are the superficial layer (first layer) of the cerebral cortex and the molecular layer of cerebellum. Synonym: plexiform layer, stratum moleculare. (05 Mar 2000) |
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| pontine gray matter | The massive gray matter filling the basilar pons. The nuclei are of fairly homogeneous architecture and project to the cortex of the contralateral cerebellar hemisphere by way of the middle cerebellar peduncle. Their main afferents come from the entire extent of the cerebral neocortex by way of the longitudinal pontine bundles (corticopontine fibres); thus, the pontine nuclei form a major way-station in the impulse conduction from the cerebral cortex of one hemisphere to the posterior lobe of the opposite cerebellum. Synonym: nuclei pontis, pontine gray matter. (05 Mar 2000) |
| heterotopic gray matter | <radiology> Presence of cortical neurons in an abnormal location secondary to arrest of migrating neuroblasts from ventricular walls to brain surface between 7-24 weeks of gestational age, frequency: 3% of healthy population associated with: agenesis of corpus callosum, aqueductal stenosis, microcephaly, schisencephaly, encephalocele X-ray: single/multiple bilateral subependymal nodules along lateral ventricles Differential diagnosis: subependymal spread of neoplasm, subependymal haemorrhage, vascular malformation, tuberous sclerosis, intraventricular meningioma, neurofibromatosis (12 Dec 1998) |
| superficial gray layer of superior colliculus | See: gray layer of superior colliculus. (05 Mar 2000) |
| deep gray layer of superior colliculus | A layer of myelinated fibres, the deepest layer of the colliculus superior, delimiting the latter from the central gray substance surrounding the cerebral aqueduct. Synonym: stratum album profundum. (05 Mar 2000) |
| digital gray scale | 1. Extent from side to side, or distance sidewise from a given point or line; breadth; width. "Provided the length do not exceed the latitude above one third part." (Sir H. Wotton) 2. Room; space; freedom from confinement or restraint; hence, looseness; laxity; independence. "In human actions there are no degrees and precise natural limits described, but a latitude is indulged." (Jer. Taylor) 3. Extent or breadth of signification, application, etc.; extent of deviation from a standard, as truth, style, etc. "No discreet man will believe Augustine's miracles, in the latitude of monkish relations." (Fuller) 4. Extent; size; amplitude; scope. "I pretend not to treat of them in their full latitude." (Locke) 5. <geography> Distance north or south of the equator, measured on a meridian. 6. <astronomy> The angular distance of a heavenly body from the ecliptic. Ascending latitude, Circle of latitude, Geographical latitude, etc. See Ascending. Circle, etc. High latitude, that part of the earth's surface near either pole, especially. That part within either the arctic or the antarctic circle. Low latitude, that part of the earth's surface which is near the equator. Origin: F. Latitude, L. Latitudo, fr. Latus broad, wide, for older stlatus; perh. Akin to E. Strew. Source: Websters Dictionary (01 Mar 1998) |
| affinity column | <investigation> A technique of analytical chemistry used to separate and purify a biological molecule from a mixture, based on the attraction of the molecule of interest to a particular ligand which has been previously attached to a solid, inert substance. The mixture is passed through a column containing the ligand attached to the stationary substance, so that the molecule of interest stays within the column while the rest of the mixture continues through to the end. Then, a different chemical is flushed through the column to detach the molecule from the ligand and bring it out separately from the rest of the mixture. (09 Feb 1998) |
| anterior column | The pronounced, ventrally oriented ridge of gray matter in each half of the spinal cord; it corresponds to the anterior or ventral horn appearing in transverse sections of the cord, and contains the motor neurons innervating the skeletal musculature of the trunk, neck, and extremities. See: gray columns. Synonym: columna anterior. (05 Mar 2000) |
| anterior column of medulla oblongata | An elongated, white prominence on the ventral surface of the medulla oblongata on either side along the anterior median fissure, corresponding to the pyramidal tract. Synonym: pyramis medullae oblongatae, anterior column of medulla oblongata, anterior pyramid. (05 Mar 2000) |
| anterolateral column of spinal cord | The lateral white column of the spinal cord between the lines of exit and entrance of the anterior and posterior nerve roots. Synonym: funiculus lateralis, anterolateral column of spinal cord, lateral funiculus of spinal cord. (05 Mar 2000) |
| branchial efferent column | A column of gray matter in the brainstem of the embryo, represented in the adult by the nucleus ambiguus and the motor nuclei of the trigeminal and facial nerves. (05 Mar 2000) |
| Burdach's column | The larger lateral subdivision of the posterior funiculus. Synonym: fasciculus cuneatus, Burdach's column, Burdach's fasciculus, Burdach's tract, cuneate funiculus, wedge-shaped fasciculus. (05 Mar 2000) |
| veins of vertebral column | Includes the internal and external vertebral venous plexuses, the basivertebral veins, and the anterior and posterior spinal veins. Synonym: venae columnae vertebralis. (05 Mar 2000) |
| general somatic afferent column | In the embryo, a column of gray matter in the hindbrain and spinal cord, represented in the adult by the sensory nuclei of the trigeminal nerve and relay cells in the dorsal horn. (05 Mar 2000) |
| general somatic efferent column | A column of gray matter in the embryo, represented in the adult by the nuclei of the oculomotor, trochlear, abducens, and hypoglossal nerves and by motor neurons of the ventral horn of the spinal cord. (05 Mar 2000) |