Cerebrum II Flashcards
What are the different classes of white matter of the cerebrum?
- Association fibers
- Projection Fibers
- Commisural fibers
What are association fibers?
white matter that connects the different parts of the same cerebral hemisphere. Classified as eithe short or long association fibers
What are projection fibers?
White matter that connects the cerebral cortex with the brainstem, cerebellum, and Spinal cord
What are commissural fibers?
White matter that connects the right and left cerebral hemisphere
List all the Long association fibers
- Cingulum
- Uncinate fasciculus
- Superior Longitudinal fasciculus
- Inferior Longitudinal fasciculus
- Fronto-occipital fasciculus
What is the cingulum?
Bundle of nerve fibers that lie within the cingulated gyrus, and connects the frontal and parietal lobes with the parahippocampal and adjacent temporal cortical region
What is the significance of the cingulum?
forms part of Papez circuit for emotional integration and recent memory formation
What is Uncinate Fasciculus?
long association fibers that hook around the floor of the stem of the lateral sulcus. It connects the anteromedial temporal lobe with the orbitofrontal cortex
A patient presents with damage to the Uncinate fasciculus. What does the patient present with?
- Deficit in object recognitiion
- Reduced verbal fluency
- Anomia
What is anomia?
unability to recall names
What is arcuate fasciculus?
Connects Broca’s motor speech area with Wernicke’s speech area. Part of uncinate fasciculus, but also referred to as a subset of superior longitudinal fasciculus
What does a patient with damage to the arcuate fasciculus present with?
Conduction aphasia
They retain the ability to speak and comprehension is preserved, but they cannot connect the two, thus the patient would be unable to repeat simple phrases
What is the Superior Longitudinal Fasciculus?
Long association fibers that connect the visual cortex [area 17] with the frontal eye field. Looked external to corona radiata
What is the Inferior Longitudinal Fasciculus?
Long association fibers that connects area 18 and 19 of the occipital cortex to the temporal lobe.
It extends longitudinally along the lateral wall of posterior horn and lateral ventricle outside the fibers of the optic radiation and tapetum of corpus callosum
What is the Fronto-occipital fasciculsus?
Long association fiber that extends anteromedially from the frontal pole to the occipito-temporal lobes. [medial to corona radiate]
List all commissural fibers
- corpus callosum
- Anterior commisure
- Posterior commissure
- Habenular commissure
- Optic chiasma
- Hippocampal commissure
What are the parts of the corpus callosum?
- Rostrum
- Genu
- Trunk/Body
- Splenium
Arranagement of Corpus Callosum Fibers
-
Forceps minor:
- fibers arise from genu
- connects medial and lateral surfaces of frontal lobes
-
Tapetum:
- fibers arise from posterior part of body
- forms roof + lateral wall of posteior horn of lateral ventricle
-
Forceps major:
- dibers arise from splenium
- connect occipital lobes
Relations of the Corpus Callosum
-
Upper surface:
- 2 ACA
- Lower margin of falx cerebri with inferior sagittal sinus
-
Below the splenium:
- PCA
- Great cerebral vein
- Pineal gland
-
In relation to the lateral ventricle
- undersurface of body forms roof of lateral ventricle
- Genu forms anterior wall of lateral ventricle
- rostrrum forms part of floor of anterior horn of lateral ventricle
What are the functions of the Corpus callosum?
Coordination of activities of the two cerebral hemispheres, transfer of learning process and speech function
[connects area 22, 39, 40, 44, and 45 from both hemispheres]
What causes split brain syndrome?
complete section of corpus callsoum
Describe the presentation of a patient with Split brain syndrome
When viewing an image in their left visual field, the patient will be unable to name the what they saw as the speech-control center is on the left, will the image seen is on the right side of the brain.
same thing is the patient’s speech-control center is on the right and an image is placed in the right visual field
What is the anterior commissure?
commissural fibers that plays a key role in pain sensation [acute, sharp] and contains decussating fibers from the olfactory tracts, that are vital for the sense of smell and chemoreception
found in front of intraventricular foramen and grooves the antero-inferior surface of the lentiform nucleus
What is the functional importance of the posterior commissure?
- important for bilateral pupillary light reflex
- interconnects pretectal nuclei, mediating consensual pupillary light reflex
Pineal galns and commissures
pineal gland is connected to thalamus through a stalk and the stalk has a dorsal lamina called posterior commissure and the ventral lamina as habenular commissure
What are the parts of the Internal capsule?
- Anterior limd
- Genu
- Posterior limb
- Retro-lentiform part
- Sub-lentiform part
Relations of the Internal Capsule
What arteries supply the internal capsule?
What fibers are contained within the anterior limb of the internal capsule?
- Fronto-pontine fibers
- Cortico striate fibers
- Medial fore brain bundle (orbital surface to hypothalamus)
- Anterior thalamic radiation
- Anterior nucleus to cingulate gyrus
- Dorsomedial nucleus to prefrontal cortex
- VA to premotor area
- VL to motorarea
What fibers are contained within the genu of the internal capsule?
- Cortico nuclear fibers
- Cortico reticular fibers
- Frontopontine fibers
- Anterior fibers of superior thalamic radiation (VPL & VPM to area 3,1&2)
What fibers are contained within the sub-lentiform of the internal capsule?
- Auditory radiation
- Inferior thalamic radiation (fibers between auditory area and temporal lobe)
- Fibres of Meyer’s loop of optic radiation (fibers from lower part of the peripheral retina)
- Tempero- pontine fibers
What fibers are contained within the retro-lentiform of the internal capsule?
- Optic radiation
- Posterior thalamic radiation (pulvinar of the thalamus to area 18, 19, 39 & 40)
- Parieto-pontine fibers
- Occipito-pontine fibers
- Cortico-fugal fibers (from area 18 & 19 to midbrain)
What fibers are contained within the posterior limb of the internal capsule?
- Cortico spinal tract
- Fronto-pontine
- Parieto-pontine fibers
- Cortico rubral fibers
- Cortico striate fibers
- Superior thalamic radiation
- area 4 with VA & VL nucleus of thalamus
- area 3,1&2 with VPL & VPM nucleus of thalamus
What fibers pass across the posterior limb of the internal capsule?
- Fasciculus subthalamicus
- fasciculus lenticularis
- nigrostriate fibers
- thalamostriate fibers
What is the Charcot’s artery of cerebral hemorrhage?
Lateral striate branch of the middle cerebral artery
What are the symptoms of a stroke, if it affects the different parts of the Internal Capsule?
- Retrolentiform part : homonymous hemianopia
- Genu + Anterior part of Posterior limb: paralysis of the face and contralateral upper limb
- Posterior limb [only]: contralateral dense hemiplagia + clasp knife patterm of spasticity + circumduction of affected limb + exaggerated deep tendon reflex
- Superior Thalamic radiation: Loss or impaired sensation on the contralateral side
What branches, when ruputured or thrombosed, would lead to a stroke affecting the internal capsule?
Lateral striate branch of the middle cerebral artery
What are the symptoms of a stroke, if it affects the retro-lentiform part of the Internal Capsule?
homonymous hemianopia
What are the symptoms of a stroke, if it affects genu of the Internal Capsule?
Genu [+Anterior part of Posterior limb] paralysis of the face and contralateral upper limb
What are the symptoms of a stroke, if it affects the posterior limb of the Internal Capsule?
- Anterior part of Posterior limb [+ Genu]: paralysis of the face and contralateral upper limb
- Posterior limb [only]: contralateral dense hemiplagia + clasp knife patterm of spasticity + circumduction of affected limb + exaggerated deep tendon reflex
What are the symptoms of a stroke if it affects the Superior Thalamic radiation of the Internal capsule
Loss or impaired sensation on the contralateral side
