White Matter

Front 1

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.

Back 1

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.

Front 2

The function of myelin is to _________ axons, promoting efficiency in electrical conduction.

Back 2

The function of myelin is to INSULATE axons, promoting efficiency in electrical conduction.

Front 3

Myelin sheaths are discontinuous, leaving ______ of _______ uncovered; this permits more efficient _________ transmission.

Back 3

Myelin sheaths are discontinuous, leaving NODES OF RANVIER uncovered; this permits more efficient AXONAL transmission.

Front 4

The four types of glial cells in the CNS are:

Back 4

The four types of glial cells in the CNS are OLIGODENDROCYTES, ASTROCYTES, EPENDYMAL CELLS, AND MICROGLIA.

Front 5

2 types of glial cells are important to structure & fx of white matter:

Back 5

2 types of glial cells are important to structure & fx of white matter: OLIGODENDROCYTES AND ASTROCYTES.

Front 6

In the CNS, ______ are responsible for the formation of myelin. In the PNS, this function is served by ______ ______.

Back 6

In the CNS, OLIGODENDROCYTES are responsible for the formation of myelin. In the PNS, this function is served by SCHWANN CELLS.

Front 7

The most common term for white matter bundles is ________ (at least within the brain); other terms include these 4:

Back 7

The most common term for white matter bundles is TRACT(at least within the brain); other terms include these 4: FASCICULUS, FUNICULUS, LEMNISCUS, PEDUNCLE

Front 8

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.

Back 8

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.

Front 9

The ______ hemisphere may have more white matter; the difference may be particularly notable in the ________ lobe.

Back 9

The RIGHT hemisphere may have more white matter; the difference may be particularly notable in the FRONTAL lobe.

Front 10

There are 3 major types of white matter pathways: ______, _______, and __________ pathways.

Back 10

There are 3 major types of white matter pathways: PROJECTIONS, COMMISURAL and ASSOCIATION pathways.

Front 11

White matter _________s consist of long tracts that both ______ and ______.

Back 11

White matter PROJECTIONS consist of long tracts that both ASCEND and DESCEND.

Front 12

Projections that ascend are called _______ tracts, while those that descend are called ________ tracts.

Back 12

Projections that ascend are called CORTICOPETAL tracts, while those that descend are called CORTICOFUGAL tracts.

Front 13

Names of specific projections include the _______-______ radiations, and the ____________ and __________ tracts.

Back 13

Names of specific projections include the THALAMO-CORTICAL radiations, and the CORTICOSPINAL and CORTICOBULBAR tracts.

Front 14

_________ white matter pathways connect the 2 hemispheres. The largest is the ______ _________, with its posterior ______, central ______, anterior _________, and ventrally directed ________.

Back 14

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.

Front 15

Besides the corpus callosum, commisural white matter pathways include the ______ commisure which connects the _____ and _______ regions, and the _________/_______ commisure which links the ________.

Back 15

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.

Front 16

The third major group of white matter pathways is that of _______ pathways, which connect cerebral areas WITHIN each hemipshere.

Back 16

The third major group of white matter pathways is that of ASSOCIATION pathways, which connect cerebral areas WITHIN each hemipshere.

Front 17

Association pathways are generally ___-directional.

Back 17

Association pathways are generally BIDIRECTIONAL.

Front 18

Association pathways contain short association fibers known as ______ or _______ fibers that link adjacent cortical gyri.

Back 18

Association pathways contain short association fibers known as "U" or ARCUATE fibers that link adjacent cortical gyri.

Front 19

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.

Back 19

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.

Front 20

The degree and integrity of neural myelination significantly influences the ______ and _______ of action ________ propagation.

Back 20

The degree and integrity of neural myelination significantly influences the SPEED and EFFICIENCY of action POTENTIAL propagation.