Neuroanatomy Flashcards
Where is in the insula?
Deep in Sylvian fissure
What is the insula?
Seat of the primary gustatory cortex
What is in the middle frontal gyrus?
Dorsolateral prefrontal cortex
Where is the cingulate sulcus?
Medial side of frontal lobe
Where is the seat of motivation?
Anterior position of adjoining cingulate gyrus
What does the orbitofrontal cortex do
associative learning decision-making
What is the inferior parietal lobe made of
Angular gyrus
Supramarginal gyrus
What is the inferior parietal lobe important for?
Visuospatial attention
Where is the primary visual cortex?
Calcarine sulcus in medial occipital cortex
Where is prosody located?
Right hemisphere
How many right-handed people have a dominant right hemisphere?
10%
How many left-handed people have a right dominant hemisphere?
20%
How many left handed people have left dominant hemisphere?
64%
How many left handed people have bilateral dominance
16%
Signs in left hemisphere lesions
Aphasia Right-left disorientation Finger agnosia Dysgraphia (aphasic) Dyscalculia (number alexia) Limb apraxia
Signs in right hemisphere lesions
Visuospatial deficits Anosognosia Neglect Dysgraphia (spatial, neglect) Dyscalculia (spatial) Constructional apraxia Dressing apraxia
Which hemisphere lesion leads to face recognition?
Bilateral
Functions of limbic system?
Mediation of emotional responses via amygdala
Influencing neuroendocrine responses via hypothalamus
Reward system regulation via nucleus accumbens
Function of amygdala?
Fear conditioning
Emotional regulation
What are the medial temporal structures?
Hippocampus
Amygdala
Entorhinal and Para hippocampal cortex
What structures are functionally related to basal ganglia but not part of structure?
Substantia nigra
Subthalamic nuclei
What are the important circuits in the basal ganglia?
Motor Oculomotor Dorsolateral prefrontal (executive) Anterior cingulate (motivation) Lateral orbitofrontal (social intelligence)
What basal ganglia dysfunction causes OCD?
Volumetric changes + higher blood flow to caudate nuclei.
Increased caudate metabolism reduces after effective treatment.
What basal ganglia dysfunction is linked with bradykinesia in Parkinsonism?
Striatal over activity
What basal ganglia dysfunction is linked to Fahr’s disease?
Progressive calcium deposition in basal ganglia.
Function of anterior thalamus
Receives mamillothalami tract and fornix
Connects to cingulate cortex
What in the thalamus is associated with visual attention?
Pulvinar
What is the ventromedial hypothalamus?
Satiety center
Where is the feeding center?
Lateral hypothalamus
What does the inferior olivary nucleus do?
Aids in motor coordination by projecting climbing fibers to contralateral cerebellar cortex via inferior cerebellar peduncle
Signs in inferior olivary nucleus lesions
Appendicular ataxia due to motor incoordination of contralateral arm and leg
Fail finger-nose test
Function of cerebellum in schizophrenia
Disrupted cortico-cerebellar circuity can lead to cognitive dysmetria - difficulty in coordinating and monitoring process of receiving, processing and expressing information
What is the midbrain made up of?
Superior and inferior colliculi
Substantia nigra
Periaqueductal grey matter
What do the superior and inferior colliculi do?
Superior - conjugate gaze control
Inferior - auditory source localization
Anatomy of oculomotor nerve.
Motor function.
Supplies 4/6 of ocular muscles
Anatomy of trigeminal nerve
Sensory + motor.
Transmits facial sensation
Controls jaw muscles
Anatomy of facial nerve.
Sensory + motor.
Transmits taste sensation
Controls facial muscles.
Anatomy of glossopharyngeal nerve
Motor control of pharynx
Parasympathetic control of parotid gland
Taste from back of tongue
Anatomy of hypoglossal
Motor control of tongue muscles
What information does the spinothalamic tract carry?
Touch
Pressure
Pain
Temperature
How does CSF go from 4th ventricle to subarachnoid space
Foramen of Magendie (single) and
Foramina of Luschka (two lateral)
Where does obstruction to CSF commonly occur?
3rd or 4th ventricle (Foramen of Monroe)
What happens in communicating hydrocephalus?
Impairment of CSF reabsorption in subarachnoid space due to partial occlusion of arachnoid villi
What does the internal carotid artery divide into?
Anterior cerebral and middle cerebral artery
What does anterior cerebral artery supply?
Medial and superior strip of lateral aspect of cerebral cortex up to parietal/occipital border
What does the middle cerebral artery supply?
Lateral aspect of cerebral cortex, including Broca’s and Wernicke’s in dominant hemispheres
What does the posterior cerebral artery supply
Inferomedial temporal lobe
Occipital lobe
What supplies the medulla?
Posterior inferior cerebellar arteries
Anterior spinal branches of vertebral arteries
What supplies the pons?
Basilar artery
Signs of carotid system TIA
Amaurosis fugax Aphasia Hemiparesis Hemisensory loss Hemianopic visual loss
Signs of vertebrobasilar TIA
Diplopia, vertigo, vomiting Choking, dysarthria Ataxia Ataxia without agraphia Hemisensory loss Hemianopic visual loss Transient global amnesia Tetraparesis LOC
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Bilateral infarct of anterior cerebral artery results in which signs
Quadriparesis (legs weaker than arms) Akinetic mutism (ventromedial or cingulate syndrome)
What supplies the caudate nucleus?
Recurrent artery of Huebner (branch of anterior cerebral artery)
Lesion effect of caudate nucleus
Initially agitated, confused
Evolves to akinesia, abulia with mutism and personality changes
What supplies the basal forebrain?
Anterior communicating artery
Signs of lesion in basal forebrain
Akinesia
Personality change - orbitofrontal dysfunction
Confabulatory amnesia
What supplies the lateral medulla?
Posterior inferior cerebellar artery
Lesion effect of lateral medulla or of thrombus in PICA?
Wallenberg’s lateral medullary syndrome.
Acute vertigo with cerebellar signs.
Ipsilateral face numbness, diplopia, nystagmus
Horner’s syndrome
IX/X nerve palsy with contralateral spinothalamic sensory loss and mild hemiparesis
Types of white matter pathways
Projection fibers
Association fibers
Commissural fibers
What are projection fibers?
Run vertically, connecting higher and lower centers of the brain
What are association fibers?
Interconnect different regions within same hemisphere of brain
What are commissural fibers?
Interconnect similar regions in opposite hemisphere.
What does the anterior commissure do?
Interconnects olfactory bulbs
What does the posterior commissure do?
Interconnects midbrain pretectal nuclei
What supplies anterior aspect and most of the body of the corpus callosum?
Pericallosal artery (from anterior cerebral artery)
Signs of vascular disruption to pericallosal artery?
Left sided apraxia and agnosia
Signs of vascular disruption to splenium?
Alexia and color anomia
Preserved ability to copy words
What does damage to Arcuate fasciculus result in?
Conduction aphasia
What is the uncinate fasciculus?
Connects orbitofrontal cortex to anterior temporal lobs.
Function of unicate fasciculus
Social cognition
Language
What makes up cortical neurons?
75% is pyramidal neurons
25% are stellate cells - not in layer 1
Which layer gives rise to association/commissural and projection fibres?
Layer 6
What are Purkinje cells?
Class of GABAergic neurons in cerebellar cortex only.
Connect to deep cerebellar nuclei via inhibitory projections.
Function of purkinje cells?
For sole output of all motor coordination in cerebellum.
Examples of circum-ventricular organs
Subfornical organ
Area postrema (chemoreceptor trigger zone)
Median eminence
Posterior pituitary
Function of brainstem cholinergic pathway?
Maintains wakefulness and REM sleep.
Origination of brainstem cholinergic pathway?
Originates from pedunculopontine and laterdorsal tegmental nuclei.
What does brainstem cholinergic pathway innervate?
Thalamic relay neurons
Reticular nuclei
Where do noradrenergic pathways originate and ascend to?
Originate in loculs coeruleus (pons)
Ascend to cortex via medial forebrain bundle
Descend to spinal cord
Name two major cortical interneuron subtypes
Parvalbumin-expressing interneurons (40%)
Somatostatin-expressing interneurons (30%) - Martinotti cells
What can reduction in expression of parvalbumin-expressing interneurons lead to?
Schizophrenia
Subtypes of parvalbumin-expressing interneurons?
Basket cells
Chandelier cells
What are basket cells?
Receive direct input from thalamocortical projections.
Form synapses with soma or dendrites of pyramidal neurons