White matter
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- Avg. brain weighs 1400 grams; by volume ca. ___ % of adult brain is white mattter; the great majority of white matter is found in [3 words], though some is found in gray matter; distinction is therefore relative.
- Avg. brain weighs 1400 grams; by volume ca. 50% of adult brain is white mattter; the great majority of white matter is found in WHITE MATTER TRACTS, though some is found in gray matter; distinction is therefore relative.
- The function of myelin is to _________ axons, promoting efficiency in electrical conduction.
- The function of myelin is to INSULATE axons, promoting efficiency in electrical conduction.
- Myelin sheaths are discontinuous, leaving ______ of _______ uncovered; this permits more efficient _________ transmission.
- Myelin sheaths are discontinuous, leaving NODES OF RANVIER uncovered; this permits more efficient AXONAL transmission.
- The four types of glial cells in the CNS are:
- The four types of glial cells in the CNS are OLIGODENDROCYTES, ASTROCYTES, EPENDYMAL CELLS, AND MICROGLIA.
- 2 types of glial cells are important to structure & fx of white matter:
- 2 types of glial cells are important to structure & fx of white matter: OLIGODENDROCYTES AND ASTROCYTES.
- In the CNS, ______ are responsible for the formation of myelin. In the PNS, this function is served by ______ ______.
- In the CNS, OLIGODENDROCYTES are responsible for the formation of myelin. In the PNS, this function is served by SCHWANN CELLS.
- The most common term for white matter bundles is ________ (at least within the brain); other terms include these 4:
- The most common term for white matter bundles is TRACT(at least within the brain); other terms include these 4: FASCICULUS, FUNICULUS, LEMNISCUS, PEDUNCLE
- White matter bundles form a rich mass of white matter w/in each hemisphere above the _______ ______; this is called the _______ _______; superior to this is the ________ ______, which is subjacent to the cortex.
- White matter bundles form a rich mass of white matter w/in each hemisphere above the INTERNAL CAPSULE; this is called the CORONA RADIATA; superior to this is the CENTRUM SEMIOVALE, which is subjacent to the cortex.
- The ______ hemisphere may have more white matter; the difference may be particularly notable in the ________ lobe.
- The RIGHT hemisphere may have more white matter; the difference may be particularly notable in the FRONTAL lobe.
- There are 3 major types of white matter pathways: ______, _______, and __________ pathways.
- There are 3 major types of white matter pathways: PROJECTIONS, COMMISURAL and ASSOCIATION pathways.
- White matter _________s consist of long tracts that both ______ and ______.
- White matter PROJECTIONS consist of long tracts that both ASCEND and DESCEND.
- Projections that ascend are called _______ tracts, while those that descend are called ________ tracts.
- Projections that ascend are called CORTICOPETAL tracts, while those that descend are called CORTICOFUGAL tracts.
- Names of specific projections include the _______-______ radiations, and the ____________ and __________ tracts.
- Names of specific projections include the THALAMO-CORTICAL radiations, and the CORTICOSPINAL and CORTICOBULBAR tracts.
- _________ white matter pathways connect the 2 hemispheres. The largest is the ______ _________, with its posterior ______, central ______, anterior _________, and ventrally directed ________.
- COMMISURAL white matter pathways connect the 2 hemispheres. The largest is the CORPUS CALLOSUM, with its posterior SPLENIUM, central BODY, anterior GENU, and ventrally directed ROSTRUM.
- Besides the corpus callosum, commisural white matter pathways include the ______ commisure which connects the _____ and _______ regions, and the _________/_______ commisure which links the ________.
- Besides the corpus callosum, commisural white matter pathways include the ANTERIOR commisure which connects the OLFACTORY and TEMPORAL regions, and the HIPPOCAMPAL/FORNICAL commisure which links the FORNICES.
- The third major group of white matter pathways is that of _______ pathways, which connect cerebral areas WITHIN each hemipshere.
- The third major group of white matter pathways is that of ASSOCIATION pathways, which connect cerebral areas WITHIN each hemipshere.
- Association pathways are generally ___-directional.
- Association pathways are generally BIDIRECTIONAL.
- Association pathways contain short association fibers known as ______ or _______ fibers that link adjacent cortical gyri.
- Association pathways contain short association fibers known as "U" or ARCUATE fibers that link adjacent cortical gyri.
- Long association fibers, all of which terminate in the frontal lobe, include these 5 types: the cingulate, the __________ fasciculus, the superior __________ fasciculus, the inferior __________ fasciculus, and the __________ fasciculus.
- Long association fibers, all of which terminate in the frontal lobe, include these 5 types: the cingulate, the ARCUATE fasciculus, the superior OCCIPITOFRONTAL fasciculus, the inferior OCCIPITOFRONTAL fasciculus, and the UNCINATE fasciculus.
- The degree and integrity of neural myelination significantly influences the ______ and _______ of action ________ propagation.
- The degree and integrity of neural myelination significantly influences the SPEED and EFFICIENCY of action POTENTIAL propagation.