export_cortical anatomy Flashcards
How many cortical neurons are present in the brain
14 billion
What are some neuronal cell types
- Stellate
- Fusiform
- Pyramidal
What are some excitatory neurotransmitters
- Glutamate
2. Aspartate
What are some inhibitory neurotransmitters
GABA
How many layers are there in the neocortex
6
How many layers are there in the allocortex
3
Where in the brain is the allocortex located?
- Olfactory cortex
- Hippocampus
- Dentate gyrus
What are the 6 layers of the neocortex
- Molecular layer
- External granular layer
- External pyramidal
- Internal granular
- Internal pyramidal
- Multiform
Features of the molecular layer
Most superficial layer, it contains horizontal axons, Golgi II cels and terminal dendritic processes.
Receives diffuse afferent fibers from the lower brain to control excitability
Features of the external granular layer
Contains closely packed granule cells. This region is poorly myelinated
Features of the external pyramidal layer
Contains pyramidal neurons, granule cells and Martinotti cells.
Commissural fibers which connect the two hemispheres and ipsilateral cortico-cortico association fibers lie within this region.
Features of the internal granular layer
Contains closely packed stellate cells.
This region is enlarged in the sensory cortex.
What is the external band of Baillarger
It is a dense horizontal myelinated plexus found in the internal granular layer
Features of the internal pyramidal layer.
Contains the largest cells - Betz cells.
It also contains pyramidal neurons, granule cells and Martinotti cells.
The main efferents from this region go to the brain stem and the spinal cord.
Internal band of Baillarger
Dense myelinated plexus which lies within the internal pyramidal layer
The internal pyramidal layer is enlarged in which cortex
The motor cortex
The internal granular layer is enlarged in which cortex
The sensory cortex
Features of the multiform cortex
It contains spindle-shaped cells.
Projects efferent fibers to the thalamus.
Brodman area 1,2,3:
Functional area: Primary somatosensory cortex
Location: Postcentral gyrus
Function: Touch
Brodman area 4
Functional area: Primary motor cortex
Location: Precentral gyrus
Function: Voluntary motor control
Brodman area 5
Functional area: Tertiary somatosensory cortex and posterior parietal association
Location: Superior parietal lobule
Function: Stereogenesis
Brodman area 6
Functional area: SMA, supplementary eye field, premotor adjacent cortex
Location: Premotor cortex and rostral adjacent cortex
Function: Limb and eye movement planning
Brodman area 7
Functional area: Posterior parietal association
Location: SPL
Function: Visuomotor control, perception
Brodman area 8
Functional area: Frontal eye fields
Location:Superior and middle frontal gyri and the medial frontal lobe
Function: Visuomotor control, perception, saccadic eye movements.
Brodman area 9,10,11,12
Functional area: Prefrontal association cortex,
Location: Superior and middle frontal gyri.
Function. Thought and cognition
Brodman areas 13,14,15,16
Functional area: Frontal eye fields
Location: Medial frontal lobe. Insular cortex.
Function: Movement planning
Brodman area 17
Functional area: Primary visual cortex
Location: Banks of the calcarine fissure
Function: Vision
Brodman area 18
Functional area: Secondary visual cortex
Location: Medial and lateral occipital gyri
Function: Vision and depth
Brodman area 19
Functional area: Temporal visual area
Location: Occipital gyri
Function: Depth
Brodman area 20
Functional area: Visual inferotemporal area
Location: inferior temporal gyrus
Function: Form vision
Brodman area 21
Functional area: Visual inferotemporal area
Location: Middle temporal gyrus
Function: Form vision
Brodman area 22
Functional area: Higher order auditory cortex
Location: Superior temporal gyrus
Function: Hearing and speech
Brodman area 23,24,25,26,27
Functional area: Limbic association cortex
Location: Cingulate gyrus, subcallosal area, retrosplenial area, parahippocampal gyrus
Function: Emotions
Brodman area 28
Functional area: Primary olfactory cortex and the limbic association cortex
Location: Parahippocampal gyrus
Function: Smell and emotions
Brodman area 29,30,31,32,33
Functional area: Limbic association cortex.
Location: Cingulate gyrus
Function: Emotions
Brodman area 34, 35, 36
Functional area: Primary olfactory cortex, limbic association cortex
Location: Parahippocampal gryus
Function: Smell, emotions
Brodman area 37
Functional area: Parietal-temporal-occipital association cortex. Middle temporal visual area.
Location: Middle and inferior temporal gyri at the temporo-occipital junction
Function: Perception, vision, reading and speech
Brodman area 38
Functional area: Primary olfactory cortex, limbic association cortex
Location: Temporal pole
Function: Smell and emotion
Brodman area 39
Functional area: Parieto-temporal-occipital association cortex.
Location: Inferior parietal lobule/angular gyrus
Function: Perception, vision, reading and speech
Brodman area 40
Functional area: Parieto-temporal-occipital association cortex
Location: Inferior parietal lobule/supramarginal gyrus
Function: Perception, vision, reading and speech
Brodman area 41
Functional area: Primary auditory cortex
Location: Heschl’s gyri and the superior temporal gyrus
Function: Hearing
Brodman area 42
Functional area: Secondary auditory cortex.
Location: Heschl’s gyri and the superior temporal gyrus
Function: Hearing
Brodman area 43
Functional area: Gustatory cortex
Location: Insular cortex and the fronto-parietal operculum
Function: Taste
Brodman area 44
Functional area: Broca’s area, lateral premotor cortex
Location: Inferior frontal gyrus/frontal operculum
Function: Speech, movement planning
Brodman area 45
Functional area: Prefrontal association cortex
Location: Inferior frontal gyrus, frontal operculum
Function: Thought, cognition, planning and behavior
Brodman area 46
Functional area: Prefrontal association cortex, dorsolateral prefrontal cortex
Location: Middle frontal gyrus
Function: Thought, cognition, planning, behavior, eye movement
Brodman area 47
Functional area: Prefrontal association cortex
Location: Inferior frontal gyrus
Function: Thought, cognition, planning and behavior.
What are the main sensory cortical areas?
- Somatosensory area - 1,2,3
- Visual area - 17
- Auditory area - 41
- Gustatory area - 43
- Olfactory area
Features of the primary somatosensory area - Brodmann 1,2,3
It is located in the post-central gyrus
Receives input from muscle spindles (3a), cutaneous (3b), deep joint receptors (2).
These receptors send afferent signals via the medial lemniscus/spinothalamic tract and are relayed to the primary somatosensory cortex via the VPLc and VPM.
Face and tongue have bilateral representation.
Features of the secondary somatosensory area
It is located on the superior bank of the lateral sulcus. Where it receives input from the primary somatosensory cortex bilaterally and the ipsilateral VPLc and VPM.
It sends information to the ipsilateral S1 and motor cortex
Features of the somatosensory association area - Brodmann 5,7
Located in the superior parietal lobule.
It integrates sensory data; lesions here cause tactile agnosias or astereognosis.
Features of the primary visual cortex
Located in the banks of the calcarine sulcus extending around the occipital pole. The macula is the posterior 1/3 of the calcarine cortex/occipital pole.
Receives its input from the LGB via the geniculocalcarine fibers. Sends its output to the superior colliculus and LGB via the internal sagittal stratum and corticofugal fibers.
Features of the secondary visual cortex - Brodman areas 18 and 19
Input LGB and pulvinar. Lesions here cause visual agnosia.
Features of the primary auditory cortex - Brodman area 41
Located in the transverse gyri of Heschl in the superior temporal gyrus. Receives its input from the MGB which is tonotopically organized ventrally. The cortex itself contains isofrequency cell columns. Lesions here will cause bilateral partial deafness but more to the contralateral side as the cochlea project bilaterally but more to the contralateral side.
The only auditory commissure needed for sound localization is the……
Trapezoid body.
Features of the gustatory area - Brodman 43
It is located in the post-central operculum. It receives input from the ipsilateral nucleus solitarius via the VPMpc
Where is the vestibular cortex located
The inferior parietal lobule.
What are the main motor cortical areas
- Primary motor - 4
- Premotor - 6a
- Supplemental motor area - 6a
- Frontal eye fields - 8
Features of the primary motor cortex - 4
It is located in the precentral cortex and is involved in voluntary motor control. Characterized by the heavy presence of Betz cells. Output includes corticobulbar and corticospinal fibers. These outputs project unilaterally with the exception of those for the eye, tongue and face.
Features of the pre-motor cortex - 6a
Located on the lateral aspect of the cortex anterior to area 4 and is involved in voluntary motor control for responses dependent on sensory input.
Receives input from cortical, VL and VA thalamic nuclei.
Lesions here cause no discernible deficit.
Features of the supplemental motor cortex - 6a
Involved in programming, planning and the initiation of motor movements. It is located on the medial aspect of the hemisphere anterior to area 4 - medial SFG. Has bilateral input and sends output to the ipsilateral area 4, 6, 5, 7, spinal cord, basal ganglia and thalamus,
Features of the frontal eye fields - Brodman 8
Lies rostral to the premotor area - caudal MFG. Initiates saccadic eye movements - stimulation causes contralateral eye deviation.
Output to the rostral interstitial nucleus of the MLF, interstitial nucleus of Cajal, paramedian pontine reticular formation and superior colliculus.
Lesions here - impaired saccadic eye movements.
Which area of S1 does not project to the motor cortex
Area 3
The motor cortex has reciprocal fibers with the entire thalamus with the exception of the…..
Thalamic reticular nulcei. The thalamic reticular nuclei receives afferent fibers from the entire cortex but does not send them back.
Which part of the cerebellum projects to the M1
Contralateral cerebellum.
Handedness may be determined by what hormone during brain development
Testosterone
Lesions in the dominant angular and supramarginal gyrus cause what syndrome?
Gerstmann’s syndrome: Right/left dissociation, finger agnosia, acalculia, agraphia and failure to appreciate hemiparesis.
Where is the motor strip usually located in relation to the coronal suture?
It is usually 4-5cm behind the coronal suture
