Chapter 16 Flashcards
(19 cards)
Name the three types of of cortex the brain is composed of.
Neocortex - makes 90%; 1/3 in gyri & 2/3 found in sulci
Paleocortex - base of cerebral hemispheres & olfactory system
Archicortex - hippocampus
What are the 6 layers in the neocortex?
- molecular layer: cell poor
- external granular layer
- external pyramidal layer
- internal granular layer
- internal pyramidal layer
- multiform layer
What clinical connection is related to learning disabilities?
faulty development of synaptic trees/spines during postnatal development correlates with learning disabilities
Name the two main types of cells in the cerebral cortex and their function(s).
Pyramidal cells - the chief cortical efferent or output neuron.
Granule (stellate) cells - the main interneurons of cortex. (especially numerous in sensory and association areas)
What is arranged perpendicular to the cortical surface and its thousands of neurons interconnect in a vertical direction?
cortical columns
What is the function of each cortical column?
I, II, III - supergranular layers - are associative and connect to other parts of cerebral cortex
IV - internal granular layer - chief input layer (thalamic)
V, VI - infragranular layers - V to corpus striatum, brainstem, & spinal cord. VI to thalamas
The four types of connections the cortical column makes are?
- Intracortical
- Association
- commissural
- Subcortical
What do intracortical fibers connect?
- these fibers are short
- connect horizontally orientated neurons in layer I
- connect horizontal branches from pyramidal cell axons
What do association fibers connect?
- connect gyrus to gyrus or lobe to lobe in same hemisphere
- short association fibers called arcuate fibers or loops
- long association fibers called bundles
- fibers chiefly rise from pyramidal cells in layers II, III
What are the main long association fibers and what do they connect?
- superior longitudinal fasciculus (above insula) connects frontal, parietal, & occipital lobes.
- arcuate fasciculus (sweeps around insula) connects frontal & temporal lobes
- inferior occipitofrontal fasciculus (ventral to insula) connects frontal, temporal, & occipital
- uncinated fasciculus connects orbital part of frontal lobe and anterior part of temporal lobe.
- cingulum: beneath cingulate & parahippocampal gyri
What is the function of the commissural fibers?
these fibers connect the two hemispheres
How does the commissural fibers connect the two hemispheres?
- the corpus callosum (4 parts)
- anterior commissure (connects inferior & middle temporal gyri)
What are the 4 parts of the corpus callosum and what lobes to they connect?
Gene & Rostrum - connect anterior part of frontal lobes
Trunk - connects posterior & superior frontal lobes, posterior parietal lobes
Splenium - connects the occipital lobes
Commissural fibers also connects certain structures what are they?
- Forceps minor connected by anterior fibers arching through menu and rostrum.
- Forceps major connected by posterior fibers arching through splenium
- Tapetum connected by fibers though lateral wall of atrium & posterior horn of lateral ventricle
What do the projection fibers connect?
- connect cerebral cortex with subcortical nuclei
- corticofungal (efferent/output)
- corticopetal (afferent/input)
What is the clinical connection of surgically transectioning the corpus callosum?
sometimes done for epilepsy & demonstrates its importance in language functions.
What is the most frequent sight of a CVA?
posterior limb of capsule
A CVA in the posterior limb of capsule causes?
- contralateral spastic hemiplegia/hemiansesthesia/possible homonymous hemianopsia
- lower facial paralysis
What is the difference between Broca’s area and Wernikie’s area?
Broca’s - expressive speech
Wernikie’s - receptive speech
