288 Neuroanatomy: Draw It to Know It
Know-It Points
Cerebral White Matter — Overview
■ Association fi bers connect areas within a
hemisphere.
■ S t r i a t a l fi bers provide communication between the
cerebral cortex and the basal ganglia.
■ C o r d fi bers either directly connect areas on opposite
sides of the neuroaxis or provide an important step in
that cross-axis connection.
■ C o r d fi bers subdivide into commissural and
subcortical fi ber bundles.
■ Subcortical projection fi bers divide into the thalamic
bundle and the pontine bundle.
■ Th e deep white matter region between the cortex and
the diencephalon is anatomically divided into the
centrum semiovale and the corona radiata.
■ Th e centrum semiovale lies above the level of the
lateral ventricles and the corona radiata lies at their
l e v e l.Long Association Fibers ( Advanced )
■ Th e superior longitudinal fasciculus connects the
parietal and frontal cortices.
■ Th e arcuate fasciculus originates in the posterior
superior temporal area and passes forward to the
frontal lobe; it is classically considered the language
conduction pathway.
■ Th e cingulum is the main white matter bundle of the
limbic system.
■ Th e middle longitudinal fasciculus spans from the
posterior end of the superior temporal g yrus to the
temporal pole.
■ Th e inferior longitudinal fasciculus is the major white
matter bundle of the ventral occipitotemporal visual
pathway, the so-called “what” pathway.
■ Th e fronto-occipital fasciculus transmits visual spatial
information to the frontal motor areas to guide
movement via the “where” pathway.Internal Capsule
■ Th e internal capsule fi lls a V-shaped wedge within the
conglomeration of the basal ganglia and thalamus.
■ Th e anterior limb of the internal capsule lies in
between the head of the caudate and the lentiform
nucleus.
■ Th e genu of the internal capsule is the bend; it lies
along the medial-lateral plane of the anterior
thalamus.
■ Th e posterior limb of the internal capsule lies in
between the thalamus and the lentiform nucleus.
■ Both the sublenticular and retrolenticular limbs lie
posterior to the posterior limb.
■ Infarction to the genu and posterior limb of the
internal capsule produces a classic and common pure
motor stroke.