cerebral cortex Flashcards
What does the cerebral cortex cover?
The cerebral cortex covers the cerebral hemispheres.
What is the composition of the cerebral cortex?
The cerebral cortex is made up of gray matter and contains around 10 billion neurons.
What increases the surface area of the cerebral cortex?
The surface area is expanded by gyri (ridges) and sulci (grooves).
What is the thickness of the cortex at the crest of a gyrus?
The cortex is about 4.5 mm thick at the crest of a gyrus.
What is the thickness of the cortex in the sulcus?
The cortex is about 1.5 mm thick in the sulcus.
What components make up the cerebral cortex?
The cerebral cortex consists of nerve cells, nerve fibers, neuroglia (supporting cells), and blood vessels.
What are giant pyramidal cells (Betz cells)?
Giant pyramidal cells (Betz cells) can be up to 120 µm in size and are located in the motor cortex.
What do the apical dendrites of pyramidal cells extend toward?
The apical dendrites extend toward the pia mater.
What do the basal dendrites of pyramidal cells do?
The basal dendrites spread laterally.
What is the axon of a pyramidal cell like?
The axon originates from the cell body and may connect within the cortex or project into deeper brain regions (white matter).
What are stellate cells?
Stellate cells are small, polygonal cells with multiple dendrites and a short axon that typically synapses with nearby neurons.
What are fusiform cells?
Fusiform cells have a vertical orientation and are mostly found in the deepest cortical layers.
Where do the inferior dendrites of fusiform cells branch?
The inferior dendrites branch in the same layer.
Where do the superficial dendrites of fusiform cells extend?
The superficial dendrites extend toward the cortical surface.
Where do the axons of fusiform cells project?
The axon projects into the white matter as projection, association, or commissural fibers.
What are horizontal cells of Cajal?
Horizontal cells of Cajal are small, fusiform cells located in the most superficial cortical layers.
What direction do the dendrites of horizontal cells of Cajal extend?
The dendrites extend horizontally.
What is the axon of horizontal cells of Cajal like?
The axon runs parallel to the cortical surface, making contact with pyramidal cell dendrites.
What are cells of Martinotti?
Cells of Martinotti are small, multipolar cells present throughout the cortex.
Where do the axons of cells of Martinotti project?
Axons project toward the pia mater, often terminating in the most superficial cortical layer.
What are radial fibers?
Radial fibers run perpendicular to the cortical surface.
What types of fibers are included in radial fibers?
Radial fibers include afferent fibers from the thalamus and axons from pyramidal, stellate, and fusiform cells.
What are tangential fibers?
Tangential fibers run parallel to the cortical surface.
What types of fibers are included in tangential fibers?
Tangential fibers include collateral branches of afferent fibers and axons from horizontal and stellate cells, as well as collateral branches from pyramidal and fusiform cells.
What are the outer and inner bands of Baillarger?
The outer and inner bands of Baillarger are well-developed in sensory areas.
How many layers does the cerebral cortex have?
The cerebral cortex has six layers.
What is the molecular layer?
The molecular layer is the outermost layer, consisting mainly of tangentially oriented fibers.
What types of fibers are found in the molecular layer?
The molecular layer contains dendrites of pyramidal and fusiform cells, axons from stellate cells, cells of Martinotti, and afferent fibers from the thalamus.
What is the external granular layer?
The external granular layer contains many small pyramidal and stellate cells.
What do the axons of cells in the external granular layer do?
The axons of these cells enter deeper layers or travel to the white matter.
What is the external pyramidal layer?
The external pyramidal layer consists mainly of pyramidal cells.
What happens to the pyramidal cells in the external pyramidal layer as you move deeper?
Pyramidal cells grow larger as you move deeper into the layer.
What do the axons of pyramidal cells in the external pyramidal layer do?
The axons of pyramidal cells project to deeper areas of the brain.
What is the internal granular layer?
The internal granular layer is packed with stellate cells and contains the external band of Baillarger.
What is the ganglionic layer (internal pyramidal layer)?
The ganglionic layer contains large pyramidal cells (including Betz cells in the motor cortex) and stellate cells.
What does the inner band of Baillarger consist of?
The inner band of Baillarger consists of horizontally arranged fibers.
What is the multiform layer (polymorphic layer)?
The multiform layer contains fusiform cells, some modified pyramidal cells, and cells of Martinotti.
What happens to the fibers in the multiform layer?
Many fibers enter or exit the underlying white matter.
What are heterotypical areas?
Heterotypical areas are areas where the typical six layers are not present and may be reduced or merged.
What is the granular cortex?
The granular cortex has prominent granular layers (layers 2 and 4) and is found in sensory areas like the postcentral gyrus.
What is the agranular cortex?
The agranular cortex has poorly developed granular layers and is found in motor areas like the precentral gyrus.
What are homotypical areas?
Homotypical areas are areas of the cortex that have all six layers.
What is the function of vertical columns of neurons in the cerebral cortex?
Vertical columns of neurons have specific functions such as sensory or motor processing.
How wide are the vertical columns of neurons in the cerebral cortex?
Vertical columns are about 300-600 µm wide.
How do cortical columns communicate with each other?
Cortical columns are connected via afferent fibers, internuncial neurons, and efferent fibers.
What is the role of horizontal cells of Cajal?
Horizontal cells of Cajal allow the activation of distant cortical columns.
Where is the precentral area (primary motor area) located?
The precentral area is located in the precentral gyrus and paracentral lobule.
What is the function of the precentral area?
The precentral area is involved in muscle movement control.
Where are giant pyramidal Betz cells concentrated?
Giant pyramidal Betz cells are concentrated in the precentral area.
What is the premotor area?
The premotor area is located in the anterior precentral gyrus and stores motor programs.
What is the function of the supplementary motor area?
The supplementary motor area, located on the medial surface of the frontal lobe, helps in planning complex movements.
What is the frontal eye field?
The frontal eye field controls voluntary eye movements.
What happens when the frontal eye field is stimulated?
Stimulation of the frontal eye field causes conjugate eye movements.
Where is Broca’s area located?
Broca’s area is located in the inferior frontal gyrus and coordinates muscles involved in speech.
What does the prefrontal cortex control?
The prefrontal cortex is responsible for personality, judgment, and initiative.
Where is the primary somesthetic area located?
The primary somesthetic area is located in the postcentral gyrus.
What does the primary somesthetic area do?
The primary somesthetic area receives sensory information from the contralateral side of the body.
How is sensory representation in the primary somesthetic area determined?
Sensory representation is proportional to functional importance, not size.
Where is the primary visual area located?
The primary visual area (Brodmann Area 17) is located in the posterior part of the calcarine sulcus.
What is the macroscopic appearance of the primary visual area?
The primary visual area has a thin cortex and visible visual stria.
What is the microscopic appearance of the primary visual area?
The primary visual area has a granular type of cortex with only a few pyramidal cells.
What fibers does the primary visual area receive?
The primary visual area receives afferent fibers from the lateral geniculate body.
Where does the primary visual area receive input from?
The primary visual area receives input from the temporal half of the ipsilateral retina and the nasal half of the contralateral retina.
What does the right field of vision represent?
The right field of vision is represented in the left hemisphere of the visual cortex.
What does the left field of vision represent?
The left field of vision is represented in the right hemisphere of the visual cortex.
Where do the superior retinal quadrants project?
The superior retinal quadrants (lower visual field) project to the superior wall of the calcarine sulcus.
Where do the inferior retinal quadrants project?
The inferior retinal quadrants (upper visual field) project to the inferior wall of the calcarine sulcus.
What does the macula lutea represent?
The macula lutea is responsible for sharp vision and is represented in the posterior part of Brodmann area 17.
What does the secondary visual area do?
The secondary visual area (Brodmann Areas 18 and 19) helps relate visual information to past experiences.
What is the occipital eye field involved in?
The occipital eye field helps track moving objects with the eyes.
Where is the primary auditory area located?
The primary auditory area (Brodmann Areas 41 and 42) is located in the gyrus of Heschl in the lateral sulcus.
What is the auditory pathway?
The auditory pathway consists of projection fibers arising from the medial geniculate body and forming the auditory radiation.
What is the function of the secondary auditory area?
The secondary auditory area helps interpret sounds and associate auditory information with other sensory experiences.
Where is Wernicke’s area located?
Wernicke’s area is located in the superior temporal gyrus and extends into the parietal region.
What is the function of Wernicke’s area?
Wernicke’s area is important for understanding written and spoken language.
Where is the taste area located?
The taste area is located at the lower end of the postcentral gyrus in the superior wall of the lateral sulcus and the insula.
What does the vestibular area control?
The vestibular area helps with the position and movement of the head and influences eye movements and postural control.
Where is the insula located?
The insula is buried within the lateral sulcus, forming its floor.
What is the function of association cortex?
The association cortex connects and integrates information, playing a role in behavior, sensory experience, and interpretation.
What is the role of the prefrontal cortex?
The prefrontal cortex is involved in personality, judgment, and initiative.
Where is the anterior temporal cortex located?
The anterior temporal cortex stores previous sensory experiences and can trigger memories.
What is the role of the posterior parietal cortex?
The posterior parietal cortex integrates visual and sensory input, helping with body image recognition.
What is cerebral dominance?
Cerebral dominance refers to the dominance of one hemisphere for specific functions.
Which hemisphere is dominant for speech in most people?
The left hemisphere is dominant for speech in over 90% of people.
What is handedness dominance?
Right-handedness, seen in over 90% of people, indicates left-hemisphere dominance.
what happens in the case of left-handed individuals?
Left-handed individuals may have more varied hemisphere specialization for language and motor control.
