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77 Cards in this Set
- Front
- Back
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Cerebellum anterior lobe in charge of
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– regulation of muscle tone; degeneration in alcoholics -> act like drunk all the time
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Cerebellum posterior lobe in charge of
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coordination of motor activity
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locculo-nodular lobe (oldest part of cerebellum) – vestibulocerebellum, role in
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maintance of balance(posture and gait) and eye movement
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Components of cerebellum
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Spinocerebellum
Corticocerebellum Vestibulocerebellum |
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Spinocerebellum
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vermis + medial hemispheres/paravermis, linked to balance, muscle tone, and synergy for stereotypical movements (posture gait)
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- Corticocerebellum
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lateral hemispheres, processes and integrates info from cerebrum, linked to dentate nucleus. Fine movement, muscle tone, non stereotypical movements (we have to think about them)
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- Vestibulocerebellum
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flocculonodular lobe, linked to balance and eye movement
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Components of the cerebellum project out to
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Upper Motor Neuron + olive to refine motor function output and improve cerebellar motor output)
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Cerebellum retains
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Somatotopic representation of the bodyu
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Cerebellar connections are divided into
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3 loops which are interconnected and lesions to any of them at any level will result in ipsilateral damage
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Loop 1 input and output
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Input: Vestibular nuclei-fastigial nuclei-vestibuloCB-Vestibular nuclei
Output-Vestibular tract effect on extensor muscles of the leg |
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Loop 2 input and output
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Input: Spinal cord-Globose nuclei and Emboliform nuclei-SpinoCB-Reticular formation and Spinal cord
Output-Reticulospinal tract |
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Loop 3 Input and output
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Input: Motor cortex-Pons-Dentate nucleus -CorticoCB-Red nucleus-VL thalamic nucleus-Motor cortex
-Output-Reticulospinal and Corticospinal/corticobulbar, tectospinal tracts |
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Inferior cerebellar peduncle characterisitics
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(mostly afferent, sensory input, from spinal cord to brainstem) = connects cerebellum to medulla
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Inferior peduncle afferents
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o Afferent Restiform body – dorsal spinocerebellar tract (from nucleus dorsalis of Clark in SC levels T1-L2 proprioceptive info from lower limb), cuneocerebellar tract (from accessory cuneate nucleus in cervical SC proprioceptive info from upper limb, above T1), olivocerellar tract (inferior olive across internal arcaute bundle contralateral cerebellar hemisphere
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Inferior cerebellar peduncle efferents
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fastigiovestibular fibers-fastigioreticular
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Inferior cerebellar juxtarestiform body
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mixed afferent /efferent
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afferents of the juxtarestiform body
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vestibulocerebellar fibers (from vestibular nuclei in floor of 4th ventricle, involved in learned movements), efferent cerebellovestibular fibers (modulate motor output)
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Middle cerebellar peduncle (aka brachium pontis) characterisitcs
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all afferent from cerebral cortex via pons) = connects cerebellum to pons,
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Pontine nuclei characterisitcs
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o Potine nuclei have not a somatotopic representation but a Cortico-Ponto-cerebllar fibers representation-> frontal lobe medially in pontine nuclei, motor cortex in paramedian, parietal lobe laterally, most lateral occipital and temporal all these is mapped onto lateral hemispheres
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Superior Cerebellar Peduncle aka brachium conjuctiivum characterisitcs
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mostly efferent to VA/VL nucleus of thalamus)= connects cerebellum to pons and midbrain, efferent
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Superior cerebellar peduncle afferent fibers
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Ventral spinocerebellar tract-arises in spinal cord
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Superior cerebellar peduncle rubrocerebellar tract comes from
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red nucleus back to cerebellum
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Superior Cerebellar peduncle efferents from
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deep cerebellar nuclei
Globose-reticular formation and red nucleus Emboliform-red nucleus Dentate:ventral lateral thalamic nucleus |
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dentothalamic tract
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(dentate nucleus ->VL ->cortex),
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), dentorubrothalamic tract
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dentate nucleus -> red nucleus ->upper limbs),
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Cerebral peduncle has which tracts
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corticospinal, corticobulbar, corticopontine tracts
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Red nucleus at the midbrain has 2 parts
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Magnocellular part
Parvocellular part |
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Magnocellular part input and output
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-Inputs from a)Globose: red nucleus to reticular formation
b) Emboliform: Red nucleus -Output to Rubrospinal tract down to spinal cord Parvocellular part - |
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Parvocerebellar part input and output
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Input from deep CB nucleus
a) Dentate nucleus (dentorubrothalamic tract): Red nucleus Ouput to Inferior Olive via Central Tegmental tract |
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Cerebellar cortex has 3 layers
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Outer molecular layer
Purkinje cell layer granule cell layer |
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- Outer molecular layer
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cell-sparce, parallel fibers, outer stellate (inhibitory) and inner basket cells (lateral inhibitory
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- Purkinje cell layer
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between molec and granule layers, only (inhibitory) output from cortex -> deep nuclei
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- Granule cell layer
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= between purkinje layer and white matter, Granule cells, excitatory granule cells -> purkinje cells, inhibited by golgi cells and excited by mossy fibers
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- Mossy fibers
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afferent excitatory fibers of spinocerebellar/pontocerebellar/trigeminocerebellar tracts, excite granule cells to discharge via parallel fibers onto purkinje cells (inhibitory of deep cerebellar input)
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- Climbing fibers
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afferent excitatory fibers of olivocerebellar tract, synapse directly onto purkinje cells
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Pyramidal tract
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Corticospinal
Corticobulbar |
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Corticospinal tract
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output to spinal cord (This is for voluntary movement like individual fingers hands and arms
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Corticobulbar tract
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output to brainstem voluntary movement like eye and tongue , mastication, facial expression mm
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Extrapyramidal tracts
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Superior colliculus gives rise to tectospinal tract output to cervical spinal cord (this for gaze control
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Ataxia Disturbances of posture and gait
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falling ipsilaterally
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– Dysmetria
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Disdiadokokinesis
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Anterior Lobe Syndrome
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due to chronic alcoholism
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– Degeneration of the anterior lobe
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leg representation
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Interior Tremor in cases of
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lesions of deep nuclei
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Brainstem Organization
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alar plate = sensory (lateral), basal plate = motor (medial – CN 3,6,12), sulcus limitans seperates sensory and motor components
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Motor Systems Represented in N
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7,9, 10
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- Somatic motor nuclei located
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most medial (CN3,4,6,12,5),
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visceral motor nuclei located
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more lateral (7,9,dorsal motor nucleus of vagus -10)
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sensory nuclei located
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(nucleus of solitary tract)
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BE nuclei located
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more ventral and lateral(5,7,nucleus ambiguous -9,10)
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- GVE located
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more dorsal – dorsal motor nuc of vagus (medulla), superior salivary nucleus (pons), nucleus ambiguus
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- GSA (7,9,10)
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nucleus of solitary tract ->trigeminal nuclear complex
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- GVA (9,10)
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chemoreceptors, stretch/pressure receptors, info via nucleus of solitary tract
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Visceral motor components
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salivary, parotid, nasal, palatine and lacrimal glands
• nerves 7 and 9 (parotid) – thorax and abdomen Motor Systems Represented in N7, 9 and 10 • nerve 10 (dorsal motor nucleus of the vagus; cardiac enervation derives from nucleus ambiguus |
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Branchial motor components
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– muscles of mastication and facial expression and
• nerves 5 and 7 (also stapedius - inner ear) – stylopharangeus (pharynx) • nerve 9 (nucleus ambiguus) – larynx and pharynx • nerve 10 (nucleus ambiguus) |
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Taste – carried in
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CN 7,9,10
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Visceral motor nuclei are
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dorsal
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branchial motor nuclei are
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lateral.
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Sensory Systems Represented in N
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N7, 9 and 10
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General visceral sensory (interoception)
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Chemoreceptors: O2, CO2 and glucose levels, and pH
• Carotid bodies and sinus, aortic arch Sensory Systems Represented in N7, 9 and 10 • Mucosa of pharynx and posterior tongue • Abdominal chemoreceptors - stomach wall near esophagus and in celiac and hepatic plexuses – Stretch and pressure receptors • Aortic arch • Abdomen • Larynx and pharynx |
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Taste submodalities evolved for their survival
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- Salt (electrolyte balance), sweet (high caloric), sour/bitter (avoid for toxins), umami (high protein
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- Papillae: filliform
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(no tastebuds)
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fungiform
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(anterior 2/3 of tongue, CN7, sweet, salt, sour),
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foliate
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(anterior 2/3 of tongue and uvula, CN7,9, sour and bitter), circumvalate (post 1/3 of tongue, CN9, sour and bitter
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We share three types of taste sensation with
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Quality
– Intensity – Hedonic value (motivation, reward) |
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Afferent nerve provides trophic
input - if it dies, then taste cells |
degenerate
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Taste pathway
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o Sensory info -> nucleus of solitary tract -> central tegmental tract -> medial VPM -> Insular cortex, Brodman area 3b
in postcentral gyrus, and orbitofrontal cortex |
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Alternate tast pathway
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via parabrachial nucleus -> RF, hypothalamus, amygdala (integrates taste with olfaction, provides anatomical substrates for the motivational aspect of taste and feeding behaviors)
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3) Olfaction – bypasses
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thalamus, directly to cortex, secondary projections to thalamus
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Olfaction pathway
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oReceptors in nasal epithelium synapse with
mitral cells and tufted cells in glomeruli within the olfactory bulb, a telencephalic outgrowth • Primary afferents from these cells run in the lateral olfactory tract to primary olfactory cortex (uncus) and amygdala and medial olfactory tract to the basal forebrain • Olfactory sensations are distributed both directly to widespread areas of the limbic cortex and indirectly via dorsomedial thalamus |
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Olfactory pathway
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o Olfactory epithelia -> mitral cells (primary output to CNS) ->converge on olfactory bulb ->anterior perforated substance ->
1) Lateral olfactory stria -> uncus “primary olfactory cortex” (=piriform cortex) • Synapses with surrounding parahippocampal cortex -> association of smells with emotion and memory 2) Medial olfactory stria -> base of forebrain (via anterior commissure) |
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Collaterals of mitral cells path
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o Collaterals of mitral cells -> accessory olfactory nucleus -> anterior commissure (collateral inhibition of mitral cells to help with convergence)
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- Olfactory cells replaced every
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30-60 days, granule and periglomerular cells also regenerated
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Odorant Representations
Converge on |
Single
Olfactory Glomeruli |
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Olfactory information is relayed from basal forebrain,
pyriform cortex and amygdala directly and indirectly to |
orbital
gyrus, hypothalamus and brainstem via dorsal medial nucleus of the thalamus |
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Olfactory System Communicates
with the Ascending Reticular Activating System how |
Basal Forebrain
to Habenula via Stria Medullaris Habenula to Interpeduncular Nucleus via Fasciculus Retroflexus |
