chapter 13/14 more neuro Flashcards
fibers in the Medial Cerebral Cortex
In the medial aspect of cerebral cortex we find a group of fibers inferior to the gray matter of the hemispheres
These myelinated fibers collectively are called the corpus callosum
The corpus callosum
connects analogous regions of the 2 hemispheres
This allows for information exchange between right and left sides
A way that parts of the cerebrum talk to each other
The corpus callosum is the floor of the longitudinal fissure and the roof of the lateral ventricles
Immediately superior to the corpus callosum
is a gyrus called the cingulate gyrus (on L and R sides)
Inferior Cerebral Cortex
In the inferior aspect of cerebral cortex we have orbital frontal cortex that includes
The olfactory sulcus above the olfactory tract
Within the parahippocampal gyrus we find the hippocampus that is involved in memory
Other landmarks include
Optic chiasm, hypophysis (autonomic regulation), cerebral aqueduct, lateral sulcus
Fibers
Projection fibers
Association fibers
Commissural fibers
Projection fibers
Fibers connecting cortex with distant locations
E.g., corona radiata
Mass of fibers running to (afferent fibers) and from (efferent fibers) cortex
Condenses at internal capsule
Association fibers
Fibers connecting regions in the same hemisphere
Short fibers connect adjacent gyri
Long fibers connect ipsilateral lobes
E.g., uncinate fasciculus, arcuate fasciculus (superior and middle frontal with P,T,O)
Commissural fibers
Fibers from 1 hemisphere to the corresponding location in the other
Corpus callosum, anterior commissure, posterior commissure
Corona Radiata
“Corona radiata” means radiating crown
Projection fibers from and to the cortex
condenses as it descends
Subcortex
Structures below the cortical mantle are called subcortical structures Subcortical structures include Basal ganglia Hippocampus Diencephalon (thalamus and hypothalamus)
Basal Ganglia
The basal ganglia are cell bodies involved in controlling background movement and initiating movement patterns Structures of the basal ganglia include Caudate nucleus Putamen Globus pallidus sub-thalamic nucleus substantia nigra
Hippocampus
Has a large role in memory
Communicates with temporal lobe and hypothalamus
Diencephalon
Components include
Thalamus
Hypothalamus
Thalamus
Paired (L & R) structures that are the final common relay for sensory information
Afferent information from the periphery about all senses (save olfaction) pass through the thalamus
Also relays information from cerebellum to motor cortex
Fibers from thalamus project to cortex via internal capsule and corona radiata
26 thalamic nuclei with differing patterns of cortical and non-cortical connections
Hypothalamus
Makes up floor of 3rd ventricle Various functions Regulates reproductive behavior Regulates desire for food/water Regulates digestive process control
Cerebro-vascular system
The vascular system of the brain works to continue the circulation of blood throughout the nervous system
Brain cells use a large amount of oxygen from the vascular system in their normal functioning
Interrupted circulation can therefore have deleterious effects
what carries blood to the brain?
The paired internal carotid and vertebral arteries carry oxygenated blood to the brain
Internal Carotids
The Internal Carotid Arteries divide into
Anterior cerebral artery
Supplies medial surface of brain, including corpus callosum & leg regions of motor strip
Middle cerebral artery
Largest branch of internal carotid
Supplies lateral surfaces of brain, including parts of basal ganglia
Anterior cerebral artery
Supplies medial surface of brain, including corpus callosum & leg regions of motor strip
Middle cerebral artery
Largest branch of internal carotid
Supplies lateral surfaces of brain, including parts of basal ganglia
Vertebral arteries
The vertebral arteries travel along anterior medulla
At superior medulla, left and right vertebral arteries join and become basilar artery
Basilar artery gives rise to
Paired posterior cerebral arteries
Supply inferior temporal and occipital and medial occipital lobe
Circle of Willis
Promotes equalized blood flow and parallel distribution
Venous drainage
Veins (venous system) provide route for transportation of de-oxygenated blood away from brain and to the lungs
Re-oxygenated at lungs
schemic CVA
Ischemic CVA
~80% of strokes are due to ischemia
Ischemia = occlusion of a blood vessel that partially/totally blocks blood supply to part of the brain
Hemorrhagic CVA
blood vessel in the brain ruptures or bleeds
An aneurysm is the dilation of a blood vessel that may put pressure on surrounding regions
A bursted anyeursm is one possible source of a hemorrhage
Types of Ischemic CVA
Thrombosis
Embolism
Embolism
Traveling particle blocks blood vessel
E.g., a blood clot
Thrombosis
Blood vessel obstruction via build up of a thrombus that reduces stops flow
E.g., atherosclerotic plaque
CVAs
A cerebro-vascular accident may result in hemiplegia, aphasia, sensory changes, including visual changes
MCA occlusion is most common and results in disability related to areas served by the MCA
Including sensory and motor deficits, and impaired language
Laterality of impairment relates to occlusion location, and is typically contralateral to occlusion location
Cerebellum
Receives sensory information from entire body and responsible for coordinating motor movements
