Forebrain part 1 Flashcards
Cerebral cortex (details)
~most complex area of the brain
~has about 20 billion neurons and 200-500 trillion synapses
Cerebral cortex (organized)
~Organized functionally by regional differences and within each functional region is organized by columns and layers
The cerebrum is divided into the ____ and ____ hemisphere
left and right hemispheres
Lobes in the cerebrum
~frontal
~parietal
~temporal
~occipital
Frontal Lobe- specific gyri
~pre-central
~superior, middle, and inferior frontal
~orbital
Temporal Lobe- specific gyri
~superior, middle, and inferior temporal
~parahippocampal
the three types of connections within the cerebral cortex and
~projection fibers
~association fibers
~commissural fibers
Projection fibers
~connections leaving the cerebral cortex going to other structures in thee neural axis
~EX: the corticospinal and corticobulbar tracts going to the spinal cord and brain stem respectively
Association fibers
~connections between adjacent areas of same hemisphere
~EX: the arcuate fasciculus between language centers of the cortex
Commissural fibers
~connection between the two hemisphere
~EX: corpus callosum
Parietal Lobe- specific gyri
~post-central
~superior parental
~angular
~supra-marginal
Neocortex has _ layers
6
Numbered fro, 1 (most____) to 6 (most ____)
1- most superficial
6-most deep; nearest deep white matter
Each layer had unique distribution of different____
types of cortical neurons & inputs & outputs
Large pyramidal cells of layer ____ have axons which form:
layer 5
~form the principal projection output from the cerebral cortex
Smaller pyramidal cells of layer ____ have axons which form _______ and layer ____ form _____
~layer 3 have axons which form commissural output
~layer 2 pyramidal cells axons for association output fibers
Input from outside the cerebral cortex, specifically the thalamus enter and end in the ____ layer
layer 4
Input from other cortical areas both association and commissural fibers primary enter and end in neurons in layers ____
1, 2, 4, & 5
Brainstem reticular activating system input into ___ layers
all layers
there are ___ different histological regions
52 different regions
Each region is defined by
~different patterns of cells in each of the layers
Brodmanns areas
~roughly corresponds to functional areas
Caveats
~not all individuals are the same (variation in size and shape of each Brodmann area from person to person)
~Boundaries of Brodmann areas are not distantly shown
~Brain plasticity can reshape the Brodmann regions, expanding some regions and contracting others so even for one individual these areas are continuously changing through their life
Cortical Columns
~neurons of similar functions organized in the same functional cortical columns
~extend from pial surface to white matter
~within a column there is a dense interconnection of neurons between layers
~most distinct cortical columns are in the primary motor and sensory cortices
Parts of the frontal lobe
~Primary motor area ~Pre-motor cortex ~Supplementary motor area (SMA) ~Broca's Motor Speech ~Frontal Eye Field ~Prefrontal cortex ~Anterior cingulate gyrus
Primary motor area is located
along the pre-central gyrus
Primary motor area (details)
~Pyramidal cells here have axons which are projection fibers that form the motor tracts to contralateral spinal cord lower motor neurons (LMN) (corticospinal tract) and to contralateral brain stem lower motor neurons (corticobulbar tract)
~has somatotopic organization (body map)
Primary motor area- somatatotopic organization
(motor homunculus)
~the size of the body parts in the homunculus represents the number of cortical neurons that are innervating LMN in the spinal cord or brainstem
~the greater areas of the homunculus represents a greater fine motor control of the muscles in that area
~greatest in hands and face
~least in trunk and lower extremities