Cerebellum & Brainstem Flashcards
Cerebellar Function
- “comparator” that compensates for error in movement by comparing intention with performance
- coordination of somatic motor activity (reg. muscle tone & equilibrium)
- cognition, emotion, affective processing
- sequencing incoming sensory patterns & detecting temporal changes in the sequence of sensory events
- anticipate & smooth out movements of trunk/limbs by slow feedback pathways (improve motor) & fast forward mech. that regulates second to second movements & keeps them on track
Vermis & Paravermian Control?
-axial musculature (neck, trunk)
Lateral Hemispheres of Cerebellum control?
-limbs (arms, legs)
Flocculonodular Lobe controls?
-maintaining balance
Lateral Hemispheres of Cerebellum project to what nuclei?
-dentate nuclei
The Paravermal Zones of Cerebellum project to what nuclei?
-globose & emboliform (interpositus nuclei)
The Vermis of Cerebellum projects to what nuclei?
-fastigial nuclei
Afferents & Efferents: Superior Cerebellar Peduncle
Afferents: Anterior Spinocerebellar Tract
Acoustic & Optic Information
Efferents: Dentatorubrothalamic Tract
Dentatothalamic Tract
Afferents & Efferents: Middle Cerebellar Peduncle
Afferents: Pontocerebellar Tract
Efferents: none
Afferents & Efferents: Inferior Cerebellar Peduncle
Afferents: Vestibulocerebellar Tract Olivocerebellar Tract Posterior Spinocerebellar Tract Efferents: Cerebellovestibular Tract Cerebelloolivary Tract
Dentatothalamic Tracts
-carry info from the lateral portions of the anterior & posterior cerebellar cortices to the thalamus & onto the contralateral motor cortex to coordinate movement in the limbs ipsilateral to the cerebellar hemisphere of origin
Cerebelloolivary Fibers
-carry info from the vermis & flocculonodular lobes through the EGF nuclei to the vestibular nuclei, the olivary nuclei, & the brainstem reticular formation
Cerebellar Cortex
-gray matter
-3 layers:
Molecular layer - Basket & Stellate cells
Purkinje Cell layer - Purkinje cells
Granule cell layer - Golgi & Granule Cells
-5 different neuron types
What are the only output neurons of the cerebellar cortex?
-Purkinje cells
What is the only direct imput to the Purkinje cells from outside the cerebelum?
-climbing fibers that have their origin in the olivary nuclei
Mossy Fibers
- imput to perkinje cells that first synapse in the cerebellar glomeruli (synapse with granule * golgi cell dendrites & with Golgi axon terminals)
- Granule cells then pass on info to Purkinje cell
Stellate & Basket Cells
-inhibitory effect on Purkinje cells
3 Functional Divisions of Cerebellum
- Vestibulocerebellum
- Spinocerebellum
- Cerebrocerebellum
Function of Vestibulocerebellum
-coordinate eye, head, neck movements & maintains balance
Function of Spinocerebellum
-coordinate trunk & proximal limb movements
Function of Cerebrocerebellum
- coordinate fine motor planning of limbs
- anticipates sensory consequences of movements
- cognitive memory of motor functions
(right controls right, left controls left)
Clinical Signs of Cerebellar Dysfunction
- unstable gait & stance with a tendency to fall, broad based gait “sailor’s gait”, reeling & drunken
- jerky/unsmooth movements, intentional tremor
- ataxia (dis-coordination): trunk or extremities
- dysmetria of movement: goal-directed movement can over or undershoot target
- eye-movement disorders: nystagmus, saccadic & smooth pursuit dysmetria
- speech disorders: ataxia dysarthria w/scanning speech, difficulty to maintain speech rhythm, intonation & correct articulation
Superior Colliculus
-functions in the control of reflex movements that orient the eyes, head, & neck in response to visual, auditory, & somatic stimuli
Periaqueductal Gray Matter
-functions in the processing of autonomic & limbic activities & modulation of nociception
Aqueduct
-passageway connecting 3rd & 4th ventricles
Nucleus of Edinger-Westphal
-parashymathetic innervation of the eye to constrict the iris & to the ciliary muscle to alter lens shape for accommodation
Cranial Nerve III nuclei & nerve
-motor control of eye muscles
Spinothalamic tract
-fiber pathway to thalamus for pain/temperature from periphery
Medial Lemniscus
-sensory pathway for proprioception connecting the nucleus gracilis & cuneatus with the thalamus
Medial Geniculate
-thalamic relay nuclei for auditory information
Lateral Geniculate
-thalamic relay nuclei for visual information
Cerebral Peduncle
-fiber bundles of the corticospinal tract connecting the cerebral cortex to the brainstem
Optic Tract
-optic fibers from optic chiasm to the lateral geniculate
Substantia Nigra
-one of several nuclei involved in smooth motor control; degenerates in parkinson’s disease
Red Nucleus
-relay nuclei b/w the cerebellum to the thalamus
Medial Longitudinal Fasciculus
-fiber pathway b/w the vestibular nuclei and the CN nuclei III, IV, VI to coordinate head/eye movements
Superior Cerebellar Peduncle
-fiber pathway to & from the cerebellum
Middle Cerebellar Peduncle
-fiber pathway to & from the cerebellum
Mesencephalic, Main sensory Nucleus, Motor Nucleus of CN V
-3 nuclear components of the trigeminal nerve nuclei
Cranial Nerve V
-motor & sensory fibers of CN V
Pontine Nuclei
-collection of neurons in the pons that receive input from the neocortex & send crossing fibers through the middle cerebellar peduncle
Locus Coeruleus
-a noradrenergic brainstem nucleus involved in mood, sleep/wake cycle
Raphe Nucleus Pontis
-one of several serotonin type nuclei involved in mood, sleep/wake cycle
Corticospinal Tract
-motor fibers from neocortex to spinal interneurons & lower motor neurons
Inferior & Medial Vestibular Nuclei
-nuclei of the vestibular system that regulate balance
Nucleus & Tractus Solitarius
-sensory nucleus for taste (CN VII), glands, chemo/baroreceptors (CN IX, X)
Dorsal Motor Nucleus Vagus (CN X)
-parasympathetic motor nucleus to lungs & gut
Spinal Nucleus & Tract of CN V
-nuclear & tract components of CN V that extends down into the upper cervical spinal cord
Inferior Olivary Nucleus
-origin of the climbing fibers the the cerebellar purkinje cells
Pyramid
-name given to the corticospinal tract fibers in medula
Reticular Formation
-network of neurons & axons that reside in the brain stem tegmentum involved in arousal, respiration, heart rate control
Nucleus CN IX
-glossopharyngeal nucleus with motor control over tongue & pharyngeal muscles with taste from
Lesions in brainstem will cause?
-contralateral signs & symptoms
Lesions in the brainstem nuclei/fascicle will cause?
-ipsilateral signs & symptoms
Structures Involved with:
- Ipsilateral 3rd nerve paresis
- Contral, hemiparesis
- Midbrain (base)
- CN III fascicles
- Cerebral Peduncle
Structures Involved with:
- Ipsilateral 3rd nerve paresis
- Contral. tremor
- Contral. ataxia
- Midbrain (tegmentum)
- CN III fascicles
- Red nucleus
- Superior cerebellar peduncle
Structures Involved with:
- Ipsilateral 3rd nere paresis
- contral. hemiparesis
- Contral. tremor
- Contral. ataxia
- Midbrain (base & tegmentum)
- CN III fascicles
- Red nucleus
- Superior cerebellar peduncle
- Substantia nigra
Midbrain Stroke Syndromes
-ipsilateral CN III palsy & loss of pupillary constriction due to damage of the oculomotor neclear complex including the parasympathetic Edinger-Westphal nucleus
Structures Involved with:
- contral. hemiparesis
- ipsilateral LMN
- facial paresis
- Medial Pons (base & tegmentum)
- corticospinal & corticobulbar tracts
- CN VII fascicles
Structures Involved with:
- contral. hemiparesis
- ipsilateral LMN
- facial paresis
- ipsilateral gaze
- paresis
- Medial Pons (base & tegmentum)
- corticospinal & corticobulbar tracts
- CN VII fascicles
- PPRF and/or CN VI
Structures Involved with:
- contral. arm/leg weakness
- contral. decrease position/vibration
- ipsilateral tongue weakness
- Medial Medulla
- corticospinal tract
- medial lemniscus
- CN XII
Structures Involved with:
- ipsilateral ataxia, vertigo nausea
- ipsilateral decrease face pain sensation
- contral. decrease body pain sensation
- ipsilateral Horner’s Dysphagia
- Lateral Medulla
- Vest. nuclei
- inc. cerebellar peduncle
- CN V & tract
- spinothalamic tract
- sympathetic fibers
- nucleus ambiguus
- nucleus solitarius