Telencephalon Anatomy Flashcards
What are the adult vesicles (parts of CNS) that arise from the telencephalon?
Cerebral hemispheres
Certebral cortex
Subcortical white matter
Basal ganglia
Basal forebrain nuclei
3 types of white matter tracts
1) Association tracts:
- link cortical regions within the SAME cerebral hemisphere
- ex: right hemisphere parietal lobe -> right hemisphere occipital lobe
2) commissural tracts:
- link corresponding cortical regions between SEPARATE hemispheres
- ex: right hemisphere -> left hemisphere
3) Projection tracts:
- link cortical and subcortical regions from around the CNS
- Ex: cortex -> outside cerebral hemispheres
Superior longitudinal fasciculus
A type of association tract
Connects the frontal and occipital lobes from the same hemisphere
Arcuate fasciculus
A type of association tract
Connects the frontal and temporal lobes of the same hemisphere
important for language function
Inferior longitudinal fasciculus
A type of association tract
Connects the occipital and temporal lobes in the same hemisphere
important for visual recognition
Uncinate fasciculus
A type of association tract
Connects anterior and inferior parts of the frontal lobe with the temporal gyri of the same hemisphere
important for behavior regulation
Cingulum
A type of association tract
Connects frontal and parietal lobes with he parahippocampal and adjacent temporal gyri of the same hemisphere
- important for emotion regulation*
Corpus callousum
A type of commissural tract
Connects both hemispheres of the brain and allows intercommunication
- also gets help from the anterior/posterior commissures*
Hippocampus commissure (fornix)
A type of commissural tract
Aids in helping the hippocampus with communicating between the hypothalamus and the hemispheres of the cerebral cortex
Also aids in right-> left hippocampus communication (and vise versa)
Split-brain
A Clinical condition that occurs when the corpus callous is split in some way
The brain still functions normally but the hemispheres work autonomously between each other
Because of this, sight, motor and speech dont work in tandom
- example: patient sees an object out of their left eye but cant name anything they see
- example: patient cant see anything out of their right eye but can use their left hand
What hemisphere is language production found?
Left hemisphere
What hemisphere is visual and motor cortex found
Both sides but are crossed
ex: right motor and visual cortex functions the left eye and hand
Alexia without agraphia
A clinical condition that occurs when the splenium portion of the corpus callousum is damaged
Causes defects in understanding written material, but they can speak and write normally
this is caused because the visual processing center on the right cant communicate with the verbal processing and motor sections on the dominant left hemisphere
What hemisphere is verbal processing found in?
Left hemisphere is dominant
Corona radiata
A type of projection tract
Cerebral cortex communicates with subcortical regions
Condenses from the cerebral cortex into the internal capsule
What does the anterior limb of the internal capsule separate?
Caudate nucleus (medial) from the putamin and the Globus palatus
What does the posterior limb of the internal capsule separate?
Thalamus (medial) from the globus palltus and the putamin
What are the 3 broad subsections of the cerebral cortex?
1) Allocortex
- includes archicortex and Paleocortex
2) Mesocortex (Juxtallocortex)
3) Neocortex (Isocortex)
Allocortex contents
Has 3 histologically layers and 2 sub catagories
Archicortex
- hippocampus
- uncus of parahippocampus
- dentate gyrus
Paleocortex
- olfactory (piriform) cortex
is largest in primitive species, but less in humans
Mesocortex contents
Is 3-5 histologically layers
Contains:
- cingulate gyrus
- all of parahippocampus except uncus
- orbitofrontal cortex
- temporal pole
- anterior insula
Neocortex contents
Has 6 histologically layers
Makes up everything else in the cerebral cortex not in the mesocortex or allocortex
most prominent in humans and less in primitive species
Overview of general limbic structures in the limbic system
Major cortical areas:
- para-hippocampal gyrus
- cingulate gyrus
- prefrontal cortex
- temporal pole
Also includes the following
- amygdala
- septal nuclei
- hypothalamus
- hippocampus formation
What is required for a structure to be considered a limbic structure?
Must either directly or indirectly communicate with the hypothalamus or midbrain Allocortex/mesocortex
Where is the primary motor cortex found in the neocortex?
Precentral gyrus to the central sulcus of the brain
- just anterior
Where is the primary somatosensory cortex found in the neocortex?
Post-central gyrus to the central sulcus
- just posterior
Where is the primary visual cortex found in the neocortex?
On the occipital lobe (posterior region)
Where is the primary auditory cortex found in the neocortex?
On the occipital lobe near the center
Unimodal association areas
Are association tracts found through out the neocortex that function to carry out higher-order information processing as it pertains to 1 sense or motor modality
Heteromodal association areas
Are association tracts found through out the neocortex that function to carry out higher-order information processing as it pertains to multiple sense or motor modalities
Brodmann areas (BA)
A way to group different parts of the cerebral cortex based on functions
Frontal lobe
Contains the following limbic structures:
- cingulate gyrus
- posteromedial orbitofrontal cortex
Contains prefrontal cortex (BA 9-12)
Contains the following areas as well
- primary motor area (M1/precentral gyrus/BA-4)
- pre-motor area (supplementary motor/BA-6/ superior frontal gyri)
- Broca’s area (inferior frontal gyri/ BA-44/45)
- frontal eye field (pre-motor cortex/ BA-6/8)
What does the frontal eye fields (BA-6/8) do?
Control eye movements only
Broca’s area (BA-44/45) function
Found on frontal lobe on the inferior frontal gyrus
Function is speech production and forming complete sentences properly
Also plays a part in interpreting actions of others
2 divisions of the prefrontal cortex
Dorsolateral region:
- function is to overall management of cognitive processes (planning/working memory)
Orbitofrontal-ventromedial region:
- function is to aid in decision making
the whole prefrontal cortex is known for decision making and cognitive awareness/planning
Inferior parietal lobule (BA-39/40)
Contains the Supramarginal gyrus and the angular gyrus
Receives input from auditory and visual vortices
Function is to perform complex perceptual discriminations and integrations
- BA-39 = angular gyrus ; BA-40 = supramarginal gyrus*
Superior parietal lobule (BA-5/7)
Integrates sensory and motor functions
Functions to build 3-D perceptions as well as programming complex motor functions w/ promotor cortex
Occipital lobe (BA 17-19) parts and functions
Primary visual areas:
- cuneus gyrus (superior to calcarine sulcus)
- Lingual gyrus (inferior to calcarine sulcus)
Secondary visual areas:
- rest of the occipital lobe
Temporal lobe functions and parts
Contains 3 main temporal gyri
(Superior, middle, inferior)
Superior:
- primary auditory area/ transverse gyri of Heschl(BA-41)
- auditory association (BA-42)
Inferior:
- perception still objects in visual fields in space
Middle:
- perception of moving objects in visual fields
Inferiotemporal cortex
Consist of the inferior temporal cortex and the occipital temporal gyri (fusiform)
Is critical for face and shape recognition
Insula (BA-43/ gustatory cortex)
Center of the cerebral cortex which has convergence with temporal/partial and frontal cortices
Associated with the following functions
- reception and integration of taste
- processing pain
- reception of visceral sensations
- vestibular functions
How is language processed
Requires transformation from wernicke’s area -> Broca’s area Via the lateral fissure (arcuate fasciculus)
1) wernickes area hears/comprehends the word
2) information understood from wernickes area then travels via the arcuate fasciculus to Broca’s area
3) Broca’s area allows speech to form and in proper sentence structure
* if reading is required, then information starts in the primary visual cortex and then travels via angular gyrus to wernickes area and continues form there*
Wernicke’s area (BA-22)
Found on the temporal and parietal lobe
Function is to comprehend language meanings and map sounds to meanings
contains the lexicon (vocabulary storage areas)
What are the two main artery supplies to the brain (before branching)?
Internal carotid
- anterior circulation
Vertebral
- posterior circulation
Major branches of the ICA that play a part in supplying the telencephalon
Anterior cerebral artery
- travels rostral through the inter hemispheric fissure
Middle cerebral artery
What structures in the telencephalon are supplied from the anterior cerebral artery from the internal carotid artery?
The whole medial cerebral hemisphere except the occipital lobe
Post central and precentral gyri (primary motor and somatosensory areas)
Olfactory bulb and tracts
Anterior hypothalamus
Parts of:
- caudate nucleus
- internal capsule
- putamen
- septal nuclei
What does the anterior communicating artery specifically supply?
Anterior hypothalamus
- this is a branch of the anterior cerebral artery*
What does the medial striate artery specifically supply?
Anteromedial head of the caudate nucleus
Parts of the Internal capsule/putamen and septal nuclei
What structures in the telencephalon are supplied from the middle cerebral artery from the internal carotid artery?
Supplies the lateral convexity of the cerebral hemisphere.
Includes
- temporal
- frontal
- parietal
- occipital
- insula
- note that once MCA reaches M2 division, it splits into inferior and superior branches, which while suppling all regions of the lateral cerebrum, each section does a little more to specific regions*
M1 segment of the middle cerebral artery
Runs laterally along the Sylvian fissure and then bifurcated into M2 segments
Gives off lenticulostriate arteries
at the site of bifurcation, aneurysms in the middle cerebral artery are common
M2 segment of the middle cerebral artery
Immediately free bifurcation and branches onto the insular cortex
occlusion here often results in gestation and viscero-sensory cognitive processing
M3 segment of the middle cerebral artery
Run along the opercula of the frontal/parietal and temporal regions near the insula
M4 segment of the middle cerebral artery
Distal cortical branches form the superior and inferior divisions and supplies the lateral convexity
Differences between superior and inferior divisions of M2-M4
All supply the same regions, but each part does a little more to specific lobes
Inferior:
- supplies more temporal lobe and occipital lobe
Superior:
- supplies more frontal and parietal lobes
Calcarine artery
Runs in the calcarine sulcus and supplies the primary visual cortex
occlusion here results in primary visual defects and visual association defects
Superficial middle cerebral vein
Runs along the lateral sulcus
Drains the temporal lobe and empties into the cavernous sinuses
Superior anastomotic vein (of Trolard)
largest superficial vein in the brain
Travels across the parietal lobe
Function is to connect the superficial middle cerebral vein w/ superior sagittal sinus
Inferior anastomotic vein (of Labbe)
Travels across the temporal lobe
Drains into the transverse sinus and functions to connect the superficial middle cerebral vein with the transverse sinus
