Neuroanatomy and Imaging Flashcards
(40 cards)
The Foramen of Munro connects
also known as the interventricular foramen
connection between the third ventricle and the lateral ventricles.
if blocked or effaced, causes reduction in CSF flow from the lateral ventricles despite no associated reduction in CSF production from the choroid plexus.
Question 3. The ventral tegmental area is located in which part of the brain? Medulla Midbrain Occipital lobe Pons Temporal lobe
group of dopaminergic cells, origin of the mesolimbic dopamine pathway that is highly significant in reward and sensations of pleasure.
located on the midbrain.
Question 4.
Hippocampus is supplied by
The hippocambal arteries mainly arise from posterior cerebral artery
and to a lesser extent from anterior choroidal artery.
What is Papez circuit?
The limbic system - James Papez in 1937
Hippocampal formation (Subiculum) → fornix → mammillary bodies → mammillothalamic tract → anterior thalamic nucleus → genu of the internal capsule → cingulate gyrus → Parahippocampal gyrus → entorhinal cortex → perforant pathway → hippocampus
Functions:
Mediating emotional response (amygdalar connections)
Influencing endocrine autonomic via hypothalamus
Hippocampus- recalling previously learning
Reward system regulation via nucleus accumberns
Motivational circuitry (cingulate and DLPFC)
Question 7. Which of the following nuclei of basal ganglia contains melanin pigment? Caudate nucleus Globus pallidus Putamen Substantia nigra Subthalamic nuclei
Substantia nigra appears black because of melanin pigment.
Major components of the basal ganglia
= collection of grey matter nuclear masses in the subcortical area.
=caudate nucleus, putamun, globus pallidus
also corpus striatum. control posture and movement
lenticular/lentiform nucleus= putamen and globus
striatum = putamen and caudate
**The subthalamic nuclei and the substantia nigra are both functionally related to the basal ganglia, but are NOT considered to be part of that structure.
The nucleus accumbens (located where the head of the caudate and the anterior portion of the putamen meet just lateral to the septum pellucidum) and the olfactory tubercle collectively form the VENTRAL STRIATUM,, which is part of the basal ganglia.
Five important circuits are described ( Alexander) and functions
motor oculomotor DLFC (executive) Anterior cingulate circuit (motivation) Lateral orbitofrontal circuit (social intelligence)
- planning movement
- abstract thought to action
- cognitive processes (caudate)
- Lesions of the caudate disrupt performance on tests involving object reversal and delayed alternation.
Prosencephalon differentiates into the
Telencephalon (cerebrum, striatum and pallidum)
Diencephalon (thalamus, subthalamus, hypothalamus
and epithalamus= habenacular nucleus and pineal gland)
Mesencephalon (midbrain)
Tectum - corpora quadrigemina, made up of the superior and inferior colliculi
Basis pedunculi
Tegmentum containing the red nucleus + periaqueductal grey matter.
Rhombencephalon differentiates into
Metencephalon - pons, rostral medulla (oral part) and
cerebellum.
Myelencephalon – caudal part medulla oblongata.
The internal capsule is supplied by the;
Internal capsule contains traversing corticospinal tract and receives blood supply from different parts of the circle of Willis.
The anterior limb is supplied by lenticulostriate branches of middle cerebral artery (superior half) & recurrent artery of Heubner off of the anterior cerebral artery (inferior half).
The genu receives supply from lenticulostriate branches of middle cerebral artery,
posterior limb is supplied by the lenticulostriate branches of middle cerebral artery (superior half) &
anterior choroidal artery off of the internal carotid artery (inferior half).
Question 11. Which structure separates the two lateral ventricles in human brain? Aqueduct of sylvius Corpus callosum Pons Septum pallidum Septum pellucidum
The body of the lateral ventricle lies immediately below the corpus callosum and they are separated by septum pellucidum.
An anomalous splitting of the septum pellucidum may be more common in schizophrenia than in general population (cavum septum pellucidum).
The third ventricle lies between thalamus and hypothalamus.
The fourth ventricle lies above the pons and just below the cerebellum. The Aqueduct of Sylvius links the third and fourth ventricles.
Circulation of CSF
- From lateral ventricle to 3rd ventricle- via Interventricular foramina of monro
- From 3rd to 4th Ventricle- via cerebral aqueduct of sylvius
- From 4th ventricle to subarachnoid space-via Foramen of Magendie (single medial) and Foramen of Luschka (two, lateral foramina)
Question 14. Which one of the following structures is involved in the visual pathway? Heschl's gyrus Inferior Colliculus Lateral geniculate body Medical geniculate body Tegmentum
The medial fibres of the optic nerve cross in the optic chiasma to join the contralateral optic tract. The lateral fibres of the optic nerve pass through the ipsilateral optic tract.
The fibres synapse in the lateral geniculate body of the thalamus.
From here the optic radiation runs within the posterior part of the internal capsule and terminates in the visual cortex.
Myers loop (damage leads to temporal HH) is part of the optic radiation, which loops anteriorly from the lateral geniculate ganglion into the temporal lobe before travelling posteriorly in the occipital cortex
Forced utilization behaviour
If the frontal lobe superior to the eye (orbitofrontal) is damaged, forced utilization can be seen. Here when objects are placed in front of the subject, an object will be picked up and used appropriately, even when the subject is told not to do so.
Question 18. In what percentage of left-handed people is the left hemisphere dominant? 0.1 0.16 0.2 0.64 0.9
dominant hemisphere mediates language and speech functions.
10% of right-handed people the right hemisphere is dominant.
In left handed people only about 20% are right hemisphere dominant as expected, with 64% left hemisphere dominant and 16% showing bilateral dominance.
Generally, apraxia results from dysfunction in the dominant hemisphere and
agnosia results from dysfunction in the non-dominant hemisphere.
Movement disorders and their leisions:
Lesions in the corpus striatum are associated with dystonia, athetosis and chorea.
Lesions in the sub thalamic nucleus:
Hemiballismus.
Lesions in the substantia nigra: Parkinson’s disease.
R vs L hemisphere leisions:
Left hemisphere lesions may produce alexia, agraphia, acalculia, colour anomia without aphasia, Broca's aphasia, Wernicke's aphasia Gerstmann syndrome.
Right hemisphere lesions may produce
constructional apraxia,
Prospagnosia, Autotopagnosia,
Visual spatial Agnosia (visualpercep), anosognosia (insight)
receptive amusia, and contralateral neglect.
where are the primary sensory and motor areas located?
Brodmann areas 3, 1 and 2 comprise the primary somatosensory cortex of the human brain (or S1) - most of which is located on postcentral gyrus.
Lesions affecting the primary somatosensory cortex produce characteristic symptoms including: agraphesthesia, astereognosia, loss of vibration, proprioception and fine touch.
The primary motor cortex (or M1) is a brain region that in humans is located in the posterior portion of the frontal lobe. It works in association with pre-motor areas to plan and execute movements. M1 is located on precentral gyrus.
2 parts of hypothalamus feeding functions
Ventromedial hypothalamus acts as satiety centre;
leision–> hyperphagia, obesity in animals
lateral hypothalamus as feeding centre.
Question 28.
Which artery supplies most part of the corpus callosum?
Infarcts of the corpus callosum are not common due likely to a rich blood supply from the main arterial systems, specifically the anterior cerebral and anterior communicating, but also from posterior cerebral arteries.
Which sides account for verbal memory and pictorial memory?
Disorders of verbal and of pictorial memory are commonly dissociated by brain injury with verbal memory being affected in left and picture memory predominantly by right brain injury;
However, this is disputed as many subjects use verbal encoding when remembering pictures.
function of angular gyrus?
inferior parietal lobe of the brain that is involved in the processing of auditory and visual input and in the comprehension of language.
is Brodmann area 39
Lesions are associated with anomia.
What are mirror neurons and where are they found
Brain imaging experiments using functional magnetic resonance imaging (fMRI) have shown that the human inferior frontal cortex and superior parietal lobe is active
when the person performs an action and also when the person sees another individual performing an action.
It has been suggested that these brain regions contain mirror neurons, and they have been defined as the human mirror neuron system. Mirror neurons help us to understand why we contantly ‘act-out’ and imitate activity that we are observing.
