Cerebellum Flashcards
Layers of the cerebellum
Cerebellar cortex, cerebellar white matter, deep cerebellar nuclei
Layers of the cerebellar cortex
Molecular, purkinje, granule
What’s important about the purkinje cell layer of the cerebellar cortex?
It is the only OUTPUT FROM the cerebellar cortex
What’s important about the granule cell layer of the cerebellar cortex?
It contains the only excitatory cells in the cerebellum
Cerebellar white matter
axons from cerebellar peduncles and purkinje cell layer.
Deep cerebellar nuclei
Embedded in white matter, axons from these nuclei GO OUT of the cerebellum.
Afferents into cerebellum
DSCt, olivocerebellar, (lateral cuneate nucleus to) cuneocerebellar tract, vestibular nuclei –> ICP
Pontocerebellar –> MCP
Unconscious Proprio pathway (cerebellum) UE
Receptors –> IL fasciculus cuneatus –> lateral cuneate nucleus –> ICP –> cerebellum
Unconscious Proprio pathway (cerebellum) LE
receptors –> IL fasciculus gracilus –> L3 dorsal nucleus of clarke –> DSCt –> ICP –> cerebellum
Vestibulocerebellar system
Flocculonodular lobe
Function: Maintain equilibrium, receives info from vestibular system and connects reciprocally w/ the vestibular nuclei
Lesion - truncal ataxia, poor visual pursuit, nystagmus
Spinocerebellar System
Vermis/Paravermis
Function: controls muscle tone and synergy of contracting muscles during gait.
Lesion - LE/Gait ataxia, dysarthria, dysmetria
Pontocerebellar system
lateral hemispheres, feed forward control system
Function: receives info from pontocerebellar and olivocerebellar tracts. Creates smooth coordinated movements
Lesion - loss of fine motor skills and coordination
Cerebellar ataxia
unable to stand w/ feet together eyes open or closed.
NORMAL pallesthesia, conscious proprioception, and ankle reflexes. Unstable even if vestibular & somatosensory are normal b/c can’t coordinate incoming information.
Somatosensory ataxia
Better balance w/ eyes open. Impaired pallesthesia, conscious proprioception, and ankle reflexes, as well as kinesthetic awareness.
Vestibular ataxia
Gravity dependent (normal movements lying down), balance better w/ eyes open, vertigo & nystagmus present.
Function of the thalamus
integrates and relays sensory info (except smell), processes some memory, regulates consciousness, arousal and attention, perception of general pain.
Three dorsal sections of the thalamus
lateral nuclear mass, anterior nucleus, medial nuclear mass
Sections of lateral nuclear mass of thalamus
Ventral lateral, ventral posterior, lateral dorsal nuclei
Ventral lateral nucleus
Motor function: motor relay station for the basal ganglia and cerebellum
Ventral posterior nucleus
sensory of face/trunk/extremities (CL)
Lateral dorsal nucleus
limbic system, pulvinar (cushion)
Anterior nuclear mass
part of limbic system
Medial nuclear mass
Dorsal median nucleus - part of limbic system, connection with frontal lobe
Centromedian nucleus
part of ascending reticular activating system
Reticular nucleus
receives info from thalamus/cerebral cortex & projects back to the thalamus. REGULATES information into the thalamus, makes you aware of sensation
What regulates the thalamus?
Cerebral cortex, reticular nucleus, reticular formation
What’s the blood supply to the thalamus?
posterior cerebral artery & posterior communicating artery
What is Thalamic Syndrome?
i.e. central pain syndrome. Usually d/t vascular lesion
What are the signs/symptoms of thalamic syndrome?
Intractable pain, CL hemianesthesia (VPL), CL decreased position sense (VPL), CL hemiplegia (post. limb of internal capsule)
What are essential tremors?
Tremors at rest and and w/ movement, no rigidity (Tx: meds, surgery, deep brain stim of VI)
Important nuclei of the hypothalamus
Supraoptic, Suprachiasmic, Arcuate, Lateral hypothalamic, ventral medial hypothalamic, paraventricular hypothalamic
Supraoptic nucleus
synthesizes and releases ADH in response to increased osmolarity in blood. Lesion = diabetes insipidus
Suprachiasmic nucleus
Connects to pineal gland via sympathetic NS. Circadian rhythm center. Receives light from retina goes to pineal gland.
Light decreases melatonin, dark increases melatonin
Arcuate nucleus
Lacks a BBB, detects concentration of leptin and insulin in the blood. Releases appetite stimulating and inhibiting hormones. Neurons in direct contact w/ blood constituents.
What is Leptin?
Hormone released by adipose cells. increased levels with increased fat, decreased levels w/ decreased fat. Decrease in leptin you want to eat. Increase in leptin you don’t want to eat.
What is conditioned hunger?
attractive foods elicit a strong insulin response –> lowers blood glucose –> stimulates appetite
Lateral hypothalamic nucleus
“hunger center”, controls initiation of eating. Lesion = eating/drinking ceases
Ventral medial hypothalamic nucleus
“satiety center” controls inhibition of eating, Lesion = overeating (hyperphagia)
Mammillary bodies of the hypothalamus
Interconnects the limbic system with the hypothalamus
Median eminence/tuber cinereum
hypothalamus - synthesize/release hormones into blood vessels of median eminence to anterior pituitary to release/inhibit other hormones.
Afferent neuronal input into the hypothalamus comes from where?
fornix & mamillothalamic tract
Efferent outflow from the hypothalamus
dorsal longitudinal fasciculus (of schutz) –> CN III, VII, IX & X & spinal cord via hypothalamospinal tract to T1-3 IMLCc & S2-S4 IMLCc
Thermoregulatory center is from
Cutaneous and visceral free nerve endings to thermoreceptive neurons in the hypothalamus
Anteromedial hypothalamus regulates
increased heat –> vasodilation –> decrease HR/BP –> increase sweating
Posterolateral hypothalamus regulates
decreased heat –> vasoconstriction –> increase HR/BP
If you activate the sympathetic NS what effect does it have on thermoregulatory effector organs?
Cutaneous blood vessel constriction (heat conservation), increase piloerector muscle contraction (generate heat)
If you inhibit the sympathetic NS what effect does it have on thermoregulatory effector organs?
Cutaneous blood vessel dilation (heat release), increase sweat gland activity (heat release)
Adrenal medulla and thyroid gland
thermoregulatory effector organs. release epinephrine and thyroid hormone. Increase body metabolism and heat production
Somatic motor system
thermoregulatory effector organ. Shivering (generate heat)
Factors affecting body temperature
time of day, age, emotions/stress, exercise, external environment, menstrual cycle, measurement site
Subthalamic nucleus
located superior to substantia nigra. Interconnects with other basal ganglia nuclei. Involved in motor control. Lesion = hemiballismus (involuntary flailing of CL limb)
Epithalamus
posterior commissure - pre-tectal neurons cross here (pupillary light reflex)
pineal gland - secretes melatonin
Parts of Metathalamus
medial geniculate nucleus, lateral geniculate nucleus
Medial geniculate nucleus
Ventral/dorsal cochlear nuclei –> lateral lemniscus –> inferior colliculus –> medial geniculate nucleus –> PRIMARY AUDITORY AREA
Lateral geniculate nucleus
IL temporal/CL nasal retinae –> lateral geniculate nucleus –> PRIMARY VISUAL CORTEX
