Deep White Matter Tracts Flashcards
What kinds of structures do association fibers connect?
Different areas of cortex within the same hemisphere.
What kinds of structures do commissural fibers connect?
Homologous structures in opposite hemispheres.
What kinds of structures do projection fibers connect?
Cortex to lower levels of the neuraxis.
What are the 4 association tracts?
- superior longitudinal fasciculus (arcuate)
- inferior longitudinal fasciculus
- uncinate fasciculus
- cingulum
What does the superior longitudinal fasciculus (arcuate) connect?
Frontal lobe into temporal lobe then into occipital. It connects frontal lobe to Broca’s and Wernicke’s area and the primary auditory cortex.
What does the inferior longitudinal fasciculus connect?
Occipital lobe and temporal lobe.
What does the uncinate fasciculus connect?
Frontal cortex based reward/punishment areas to the temporal lobe based memory systems.
What does the cingulum connect?
Subcallosal gyrus in frontal lobe to parahippocampal gyrus in temporal lobe.
What are short distance fibers called?
“U fibers” and they help to establish reciprocal connections between structures.
What are the 4 commissural fibers?
- corpus callosum
- anterior commissure
- hippocampal commissure
- posterior commissure
What does the corpus callosum connect?
Cortex areas. Includes the body, genu, and splenium.
What does the anterior commissure connect?
Anterior temporal lobes, which contains the primary olfactory cortices.
What does the hippocampal commissure connect?
Crura of the fornices, where they come together in the middle. Overall, the two hippocampal structures.
What does the posterior commissure connect?
Two sides of rostral midbrain. It is essential for upward gaze and the pupillary light reflex (consensual) .
Describe the path of the projection fibers?
In the cortex they are collectively the corona radiata, become the internal capsule when they surround the lenticulate nucleus, then become the crus cerebri in the midbrain.
