Cerebral Hemispheres Flashcards
Cerebrum
contains 2 cerebral hemispheres, hippocampus, basal ganglia and olfactory bulb
Wrinkling = 2 points
1) Increased degrees of wrinkling are associated with more complex behaviour, and social interaction.
2) This folding produces the characteristic sulci (creases) and gyri (ridges) that maximise the surface area of the cerebral cortex
cerebral cortex = 3 points
1) This cortex is a thin surface layer of “Grey Matter” where most of the brains analytical activity occurs
2) Approximately 70% of the cerebral cortex is hidden within the depths of the sulci
3) The cerebral cortex is primarily analytical, whilst instinctive behaviour, emotions, reflex movements and vegetative control are regulated in the limbic system, brain stem and cerebellum
Grey matter
4-6mm thick layer of nerve cell bodies, dendrites and synapses that cover each hemisphere (cerebral cortex) and a number of nuclear masses buried deep within the white matter, forming the sub-cortical nuclei (including basal ganglia, thalamus, amygdala, etc …)
White matter
comprises the bulk of the hemispheres beneath the surface, and consists of myelinated nerve axons linking one area of grey matter with another
corona radiata
1) Inside the hemispheres, fibres emerge from, and converge on, the cerebral cortex in the fan-shaped corona radiata, a white matter sheet
2) These fibres, passing between the cortex and subcortical areas are condensed into a boomerang-shaped sheet called the internal capsule
median longitudinal fissure = 2 points
1) A deep midline cleft separates the two hemispheres,
the median longitudinal fissure (sulcus), down as far as the corpus callosum, a large sheet of white matter connecting the hemispheres
2) Extending into the longitudinal fissure from above is the falx cerebri, a meningeal fold which prevents torsional (twisting) forces damaging the hemispheres
lateral sulcus
The most obvious division in each hemisphere is the lateral sulcus, which separates frontal and parietal lobes above, from the temporal lobe, below
central sulcus = 2 points
1) Also on the lateral surface, is a sulcus running from the median longitudinal fissure to the lateral sulcus, called the central sulcus
2) This sulcus separates the frontal from the parietal lobes; the frontal lobe comprising the entire region anterior to the central sulcus
precentral gyrus = 2 points
1) Immediately in front of the central sulcus and parallel to it is the precentral gyrus, which is the primary motor region of the cerebral cortex
2) In front of the precentral gyrus lies the premotor cortex including the superior, middle and inferior frontal gyri
postcentral gyrus = 2 points
1) Behind the central sulcus and parallel to it is the postcentral gyrus, where is located the primary somatosensory cortex
2) Posterior to the postcentral gyrus, the intraparietal sulcus divides the remainder of the lobe into superior and inferior parietal lobules
insula
Deep in the lateral fissure lies the insula, which is normally covered by the parts of the frontal, parietal and temporal lobes called the operculae
temporal lobe = 2 points
1) lies beneath the lateral fissure and its lateral surface is divided into three gyri running parallel to the lateral fissure; superior, middle and inferior temporal gyri.
2) The primary auditory cortex occupies the superior temporal gyrus, specifically the anterior transverse temporal gyrus (of Heschl), deep within the lateral fissure
occipital lobe = 3 points
1) on its medial surface the calcarine sulcus marks the location of the primary visual cortex
2) Also on the medial surface the cingulate gyrus is prominent, sitting on the corpus callosum; it is part of the limbic system, which involves portions of the frontal, parietal and temporal lobes.
3) The cingulate gyrus curves posteriorly and inferiorly around the splenium of the corpus callosum, becoming continuous with the parahippocampal gyrus
