358 Neuroanatomy: Draw It to Know It
Know-It Points
Limbic System, Part 1
■ Th e limbic system forms outer and inner rings around
the diencephalon.
■ Th e anterior cingulate g yrus is part of the anterior
network of motivation, attention, and behavior and is
associated with the amygdala.
■ Th e posterior cingulate g yrus is part of the posterior
network of learning and memory and is associated
with the hippocampus.
■ Th e parahippocampal g yrus forms the inferior aspect
of the limbic g yrus; it channels information to and
from the hippocampus to help in memory
consolidation.
■ Th e hippocampus lies along the anteroposterior
length of the superior aspect of the parahippocampal
g yrus; it is the center for memory processing.
■ Th e amygdala divides into corticomedial and
basolateral groups.
■ Th e corticomedial group of the amygdala connects,
most notably, to the olfactory system and
hypothalamus for autonomic function.
■ Th e basolateral group of the amygdala connects, most
notably, to the thalamus and prefrontal cortex for
such functions as sensory processing of visual,
auditory, and somatosensory stimuli.Limbic System, Part 2 ( Advanced )
■ Th e cingulum spans the cingulate and
parahippocampal g yri.
■ Th e cingulum, most notably, interconnects
intracingulate areas and synapses in the hippocampus.
■ Via the stria terminalis, the amygdala projects to the
septal nuclei, bed nucleus of the stria terminalis, and
hypothalamus.
■ Th e fornix emerges from the hippocampus, wraps
around the thalamus, and passes anteriorly in midline
just below the corpus callosum.Hippocampus: Anatomy
■ Th e subdivisions of the cornu ammonis from the
dentate g yrus to the subiculum are CA4, CA3, CA2,
and CA1.
■ CA1 forms the largest stretch of Ammon’s horn and
is distinctively susceptible to anoxic injury.
■ Th e entorhinal and perirhinal cortices form the
anterior parahippocampal g yrus.
■ Th e posterior parahippocampal g yrus is referred to
as the parahippocampal cortex and corresponds to
Von Economo areas TF and TH.
■ Th e uncus forms the anterior g yral thumb of the
parahippocampal g yrus.