LIMBIC SYSTEM Flashcards
RHINENCEPHALON (SMELL BRAIN) structures
Olfactory nerve rootlets Olfactory bulb Olfactory tract Olfactory striae Primary olfactory cortex
limbic lobe components
Subcallosal gyrus, inferior to the genu and rostrum of the corpus callosum, just anterior to the lamina terminalis
Cingulate gyrus
Isthmus of the cingulate gyrus, posterior and inferior to the splenium of the corpus callosum
Parahippocampal gyrus (and the underlying hippocampal formation and dentate gyrus)
Uncus
The limbic lobe is formed of ______(hippocampal formation and dentate gyrus),_____ (rostral parahippocampal gyrus and uncus), and ______ (cingulate gyrus).
archicortex
paleocortex
juxtallocortex or mesocortex
The circuit consisted of outflow of impulses from the hippocampus via the fornix
to the mamillary bodies of the hypothalamus;
from there, via the mamillotha-la-mic tract, to the anterior thalamic nucleus;
and, via the thalamocortical fiber system, to the cingulate gyrus, from which impulses returned to the hippocampus via the entorhinal area
Papez circuit
Parts of the hippocampus
hippocampus dentate gyrus (fascia dentata), and subiculum
The ______ is the part of the parahippocampal gyrus that is in direct continuity with the hippocampus.
subiculum
Laminations of the hippocampus
the molecular layer,
the pyramidal cell layer,
and the stratum oriens (polymorphic layer).
hippocampus has been subdivided further into fields:
CA1: the largest hippocampal field in humans
CA2
CA3
CA4: CA4 constitutes the transition zone between the hippocampus and the dentate gyrus.
pyramidal neurons are highly sensitive to anoxia and ischemia in this area and because it is the trigger zone for some forms of temporal lobe epilepsy
Field CA1 (also known as Sommer’s sector and the vulnerable sector)
_______have been referred to as resistant sectors because they are less sensitive to anoxia. ________ (the Bratz sector) is also called the medium vulnerability sector because of its medium sensitivity to hypoxia.
CA2 and CA3
CA4
There are basically two types of neurons in the hippocampus:
the principal neurons (pyramidal cell) and the intrinsic neurons (polymorphic cell, basket cell)
They are the only neurons with axons which contribute to the outflow tract from the hippocampus.
Principal Neurons.
They are inhibitory (GABAergic) to pyramidal cell activity
intrinsic neurons
Layers of the dentate gyrus/ subiculum
molecular layer: continuous with that of the hippocampus
a granular cell layer: small, densely packed granular cells whose axons form the mossy fiber system which links the dentate gyrus and the hippocampus
and a polymorphic layer: include pyramidal and basket cells
The bulk of extrinsic input to the hippocampal formation comes from the:
entorhinal area (Brodmann’s area 28) of the parahippocampal gyrus and, to a lesser extent, the septal area
Fibers from the septal nuclei reach the hippocampus via the __________
fornix.
Axons of small pyramidal neurons (granule cells) in the dentate gyrus reach the hippocampus via the_______
mossy fiber pathway.
Fibers from the________originate from cell groups in the vicinity of the mamillary body and exert a strong inhibitory influence on the hippocampus.
hypothalamus