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225 Cards in this Set
- Front
- Back
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What structures make up the basal nuclei?
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Caudate
Putamen Globus pallidus Subthalamic nuclei Substantia nigra |
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What structures make up the lentiform nucleus?
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Putamen
Globus pallidus |
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What structures make up the striatum?
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Caudate
Putamen Globus Pallidus |
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What is the general role of the basal nuclei?
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They are groups of cell bodies that modify/adjust motor activity by sending axonal projections to the thalamus (which will influence the motor cortex)
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How do the basal nuclei function?
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Disinhibition - they release the motor cortex from being inhibited by the thalamus - output of the basal nuclei is the globus pallidus.
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What is the first step in the direct pathway involving the basal nuclei?
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The first step is excitation via Glutamate of the striatum (caudate, putamen) by axons from the cortex (parietotemporal)
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What is the second step in the direct pathway involving the basal nuclei?
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The second step is inhibition via GABA of the Globus Pallidus by the striatum (caudate, putamen)
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What is the third step in the direct pathway involving the basal nuclei?
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The inhibited Globus Pallidus is not exerting its inhibitory effect on the thalamus, resulting in disinhibition of the thalamus.
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How does disinhibition occur at the thalamus?
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The Globus Pallidus, which normally inhibits the thamaus, is inhibited by the striatum.
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What is the effect of disinhibiton of the thalamus?
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VL and VA are no longer inhibited, and so they release Glutamate via axons into the cerebral cortex, which causes increased motor cortex activity and more movement.
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What is the first step in the indirect pathway involving the basal nuclei?
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Excitatory NT are released by axons from the cortex (occipitotemporal) onto the striatum (caudate, putamen)
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What is the second step in the indirect pathway involving the basal nuclei?
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The striatum (activated by Glutamate) releases GABA onto specific cell bodies in the globus pallidus which project to the subthalamic nucleus.
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What is the third step in the indirect pathway involving the basal nuclei?
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The inhibited axon from the Globus Pallidus to the Subthalamic Nucleus would normally inhibit cell bodies in the Subthalamic Nucleus which would excite the Globus Pallidus, so the Subthalamic Nucleus is disinhibited.
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What is the result of disinhibition of the subthalamic nucleus in the indirect pathway?
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The subthalamic nucleus, no longer inhibited, excites the globus pallidus, effecting inhibition of the thalamus - which results in a decrease in motor cortex activity and decreased movement.
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What kinds of disturbances can be caused by lesions in the basal nuclei along the direct and indirect pathways?
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Hypokinetic disturbances
Hyperkinetic disturbances |
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What is a hypokinetic distubance?
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Lesions of striatum, resulting in loss of connections between the striatum and the globus pallidus, resulting in allowing the globus pallidus to inhibit the VL of the thalamus, causing decreased motor activity.
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What are some forms of hypokinetic disturbances?
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Akinesia - impairment in initiating movement
Bradykinesia - reduction in velocity and amplitude of movement (inappropriate activation of antagonist muscles) |
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What is a well known disease classified as a hypokinetic disorder?
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Parkinson's Disease - a hypokinetic disorder with both akinesia and bradykinesia.
Caused by loss of Dopaminergic neurons in the substantia nigra (followed by serotonin and noradrenaline losses). Onset between ages 45-65. |
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What are the signs and symptoms of Parkinson's disease?
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Slight asymmetrical gait
Vague clumsiness of the hands Decreased eye blinking Blank stare Decreased arm swinging Tremor at rest "Pill rolling" movement with fingers Cogwheel rigidity (increased muscle tone) Flexed posture, paucity of movement Shuffling of feet when starting to walk |
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How is Parkinson's disease treated?
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L-Dopa with Carbidopa
Ablative surgery of globus pallidus or ventral thalamus Surgery to implant electrodes in thalamus, globus pallidus, subthalamic nucleus |
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What drug has been shown to (essentially) cause Parkinson's disease?
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MPTP (1 methyl 4 phenyl 1,2,3,6 tetrahydropyridine)
Now it is used to study Parkinson's |
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What is the role of the neurons in the substantia nigra?
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They inhibit the indirect pathway and excite the direct pathway
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How does loss of dopaminergic neurons in the substantia nigra affect the pathways?
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Results in disinhibition of the indirect pathway (increased activity)
And inhibition of the direct pathway (decreased activity) |
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Which receptors in the striatum does dopamine bind to?
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D1 and D2
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What are the three types of hyperkinesic disturbances (dyskinesias)?
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Ballismus
Choreiform movements Athetoid movements |
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Describe Ballismus.
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Occurs on one side of the body, uncontrolled flinging of upper and lower extremities.
Caused by a lesion on the contralateral side of the subthalamic nucleus. |
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Describe Choreiform movements.
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Irregular, brisk dance-like movements of limbs, may occur in face, a decrease in muscle tone
Caused by an indirect basal nuclei lesion, seen in Huntington's and over-treated Parkinson's |
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Describe Athetoid movements.
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Writhing of distal portions of extremity, slow writhing movements
More common in upper extremities, face, hands Caused by a direct basal nuclei pathway lesion |
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What is Huntington's disease?
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A genetic disorder with hyperkinetic disturbances
Onset 35-40 years of age, death 10-15 years later 90% loss of striatal neurons, loss of ACh MRI - the head of the caudate appears small and flattened |
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What are the early symptoms of Huntington's disease?
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Absent mindedness
Irritability Depression Clumsiness Falls |
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What are later symptoms of Huntington's disease?
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Choreiform movements
Cognition and speech decline Severe dementia Psychological disorders |
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What is Sydenham's chorea?
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An autoimmune disease affecting children as a consequence of rheumatic fever.
6 months after infection and lasts 3-6 weeks |
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What are some signs of Sydenham's chorea?
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Chorea that is flowing and restless
Muscular weakess Hypotonia Behavioral complications: Obsessive compulsive problems, attention deficit, irritability |
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What is the role of the cerebellum?
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It coordinates movement and postural controls by comparing actual motor output to the intended movement and then adjusting the movement as necessary.
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What fibers send intended movements (2)?
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Corticopontine fibers - synapse in the pontine nuclei
Pontocerebellar fibers - synapse in the cerebellum |
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How does proprioceptive information from muscle spindles and golgi tendon organs travel to the cerebellum?
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Travels via the dorsal and ventral spinocerebellar tracts (LE) and the cuneocerebelar tracts (UE) - to reach the cerebellum
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What are the three cerebellar lobes?
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Anterior lobe
Flocculonodular lobe Posterior lobe |
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What tracts does cerebellar output influence?
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Corticospinal
Corticobulbar Rubrospinal Vestibulospinal Reticulospinal |
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List the hemispheres of the cerebellum.
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2 lateral hemispheres
2 paravermal hemispheres 1 midline vermis |
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What are the four cerebellar nuclei?
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From more lateral to medial:
Dentate Emboliform Globose Fastigial |
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What are the arteries that supply blood to the cerebellum?
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Superior Cerebellar Artery
Anterior Inferior Cerebellar Artery Posterior Inferior Cerebellar Artery |
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What are the lateral fissures in the cerebellum?
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Primary fissure - divides the anterior and posterior lobes
Posterolateral fissure - divides posterior and flocculonodular lobe |
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What are the components of the flocculonodular lobe?
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Flocculus - more lateral
Nodulus - more medial |
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What is the role of the inferior cerebellar peduncles?
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Carries information from the spinal cord and medulla into the cerebellum - connections to and from the vestibular nuclei use the inferior cerebellar peduncle to travel to and from the cerebellum.
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What is the role of the middle cerebellar peduncles?
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They bring pontocerebellar fibers into the cerebellum
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What is the role of the superior cerebellar peduncles?
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Sends fibers from the cerebellum out to the diencephalon and brainstem
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What arteries supply the anterior lobe mostly?
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Superior cerebellar artery
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What arteries supply the posterior lobe?
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Superior cerebellar artery
Posterior inferior cerebellar artery Anterior inferior cerebellar artery |
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What are the three layers of the cerebellar cortex (gray matter)?
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Granule cell layer
Purkinje cell layer Molecular cell layer |
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What is in the cerebellar cortex?
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Gray matter, comprised of cell bodies
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Describe purkinje cells.
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The only EFFERENT neurons in the cerebellar cortex - send to cerebellar or vestibular nuclei and release inhibitory GABA
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What are the three functional cerebellar modules?
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Vestibulocochlear module
Spinocerebellar module Pontocerebellar module |
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What are the basic components of each functional cerebellar module?
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Part of the cerebellar cortex
White matter (axons) At least one deep cerebellar nucleus |
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What are the lobes and nuclei involved in the vestibulocerebellar module?
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Flocculonodular lobes
Vermis Fastigial nucleus |
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What are the afferents in the vestibulocerebellar module?
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Vestibular ganglia carry information about position of the head and body in space and eye orientation;
Brainstem and diencephalon (via pontocerebellar fibers) carry information about eye movements |
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What are the efferents in the vestibulocerebellar module?
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Purkinje cells in cerebellar cortex of flocculonodular lobe and vermis project axons via the inferior cerebellar peduncles to inhibit the ipsilateral vestibular nuclei.
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Where do the fastigial nuclei project in the vestibulocerebellar module?
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They project bilaterally to excite vestibular and reticular nuclei.
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What modalities are affected by dysfunction of the vestibulocerebellar module, and what S/S could be present?
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Influences posture, balance, equilibrium
S/S - truncal ataxia, falls, wide based stance, cannot walk heel-toe, nystagmus |
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What are the zones and nuclei of the spinocerebellar module?
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Vermal and Intermediate Zons
Fastigial, Globose, and Emboliform nuclei |
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What are the afferent parts of the spinocerebellar module?
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Dorsal and ventral spinocerebellar and cuneocerebellar tracts
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What are the efferent parts of the spinocerebellar module?
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Fastigial nuclei project to control the axial muscles, and emboliform and globose nuclei project out to control limbs, to the red nucleus in the midbrain, and the VL of the thalamus.
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What zones and nuclei are in the pontocerebellar module?
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Lateral zone
Dentate nucleus |
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What are the components of the afferent part of the pontocerebellar module?
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Pontocerebellar fibers from the contralateral pontine nuclei, inferior olivary nucleus
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What are the efferent components of the pontocerebellar module?
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Dentate nucleus projects axons up and out via the superior cerebellar peduncles to the motor areas, contralateral red nucleus, and contralateral VL of the thalamus.
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What is the role of the pontocerebella modue?
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Responsible for planning and control of precise dexterous movements in the arm and forearm and hand and timing of these movements.
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Are cerebellar lesions ipsilateral or contralateral?
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Always ipsilateral
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What is ataxia?
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Voluntary, normal strength, inaccurate, jerky movements
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What kind of cerebellar lesion would cause truncal ataxia?
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Flocculonodular and vermal lesions
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What kind of cerebellar lesion would cause gait and limb ataxia?
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Paravermal (intermediate) lesions
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What kind of cerebellar lesion would cause hand ataxia?
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Lateral lesions
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What are some consequences of pontocerebellar and spinocerebellar dysfunction?
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Dyssynergia
Hypotonia Ataxia Dysmetria Tremor Dysdiadochokinesia |
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What are some consequences of pontocerebellar and spinocerebellar dysfunction?
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Dyssynergia
Hypotonia Ataxia Dysmetria Tremor Dysdiadochokinesia |
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What are some consequences of pontocerebellar and spinocerebellar dysfunction?
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Dyssynergia
Hypotonia Ataxia Dysmetria Tremor Dysdiadochokinesia |
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What is Dyssynergia?
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Deterioration of coordinated movement and decomposition of movement
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What is Dyssynergia?
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Deterioration of coordinated movement and decomposition of movement
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What is Dyssynergia?
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Deterioration of coordinated movement and decomposition of movement
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What is Hypotonia?
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Decreased muscle tone and DTRs
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What is Hypotonia?
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Decreased muscle tone and DTRs
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What is Hypotonia?
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Decreased muscle tone and DTRs
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What is dysmetria?
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Past pointing either by overshooting target (hypermetria) or undershooting target (hypometria).
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What is dysmetria?
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Past pointing either by overshooting target (hypermetria) or undershooting target (hypometria).
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What is dysmetria?
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Past pointing either by overshooting target (hypermetria) or undershooting target (hypometria).
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What is tremor?
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Intention tremor - during performance of voluntary movement, tremor becomes more obvious as movement nears endpoint.
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What is tremor?
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Intention tremor - during performance of voluntary movement, tremor becomes more obvious as movement nears endpoint.
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What is tremor?
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Intention tremor - during performance of voluntary movement, tremor becomes more obvious as movement nears endpoint.
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What is dysdiadochokinesia?
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Awkward performance of rapidly alternating movements
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What are the four major components of the diencephalon?
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(Ventral) Thalamus
Hypothalamus Subthalamus Epithalamus |
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Relative to one another, where are the superior colliculus, pineal gland, dorsal thalamus, posterior horn of the lateral ventricle.
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Superior colliculus is medial
Pineal gland is directly lateral to the superior colliculus The dorsal thalamus is directly superior-lateral to the dorsal thalamus The posterior horn of the lateral ventricle is most lateral to the pineal gland |
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From rostral to caudal, in a side view, where are the hypothalamus, metathalamus, and subthalamus?
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From rostral to caudal...
Hypothalamus - Subthalamus - Metathalamus |
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What is contained within the metathalamus?
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Medial geniculate nucleus (MGN)
Lateral geniculate nucleus (LGN) |
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In a sagittal section of the diencephalon, what features should be visible?
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Superior to inferior...
Corpus callosum Fornix Stria medullaris thalami (turning caudally to the habenula, then pineal gland) Dorsal thalamus (bounded anteriorly and posteriorly by the commissures) Hypothalamic sulcus (more posteriorly the subthalamus, and superior and inferior colliculi; anteriorly is the lamina terminalis) Optic chiasm, mammillary body, midbrain, pon Pituitary |
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In sagittal section of the diencephalon (in the flesh) what features are most easily visible?
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Fornix
Anterior commissure Stria medullaris Dorsal thalamus Hypothalamus Posterior commissure Pineal gland |
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In coronal section of the diencephalon, what structures should be visible?
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Fornix (medial)
Stria medullaris thalami (bilateral, medial) Caudate nucleus (bilateral, lateral) Thalamus (bilateral lobes) Hypothalamus (medial, below the third ventricle and thalamus) Subthalamus (bilaterally, lateral to hypothalamus) Internal capsule (bilaterally, lateral) and lateral to that is the lentiform nuclei (putamen, globus pallidus) Lateral geniculate nucleus |
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What is the largest part of the diencephalon?
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The (dorsal) thalamus
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What information is integrated by the thalamic nuclei?
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The nuclei integrates sensory, motor, and limbic information (emotional, memory)
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Describe the location of the thalamus.
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Extends anterior-posterior from the interventricular foramen to the posterior commissure and transversely from the internal capsule to the third ventricle.
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The anterior end of the thalamus is close to what foramen?
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Behind the interventricular foramen
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Describe the location of the posterior end of the thalamus.
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Goes to the pulvinar, which overhangs the superior colliculus
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What attaches the two thalami?
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Massa intermedia
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The superior thalamus is grooved by what structures?
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Grooved by the fornix and the stria medullaris thalami, which runs along the media aspect of the thalamus
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To what area of the brain does the thalamus have extensive reciprocal input?
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The cortex
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What are the three categories of location for nuclei?
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Medial thalamic nuclei
Lateral thalamic nuclei Central intralaminar nuclei |
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What are the medial thalamic nuclei (location)?
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Dorsomedial nuclei
Small midline nucleus |
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What are the two tiers of the lateral thalamic nuclei (location)?
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Dorsal and Ventral tiers
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What comprises the dorsal tier of the lateral thalamic nuclei (location)?
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Lateral dorsal nuclei
Lateral posterior nuclei Pulivnar nuclei Medial geniculate nuclei Lateral geniculate nuclei |
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What nuclei are in the ventral tier of the lateral thalamic nuclei (location)?
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Ventral anterior nuclei
Ventral lateral nuclei Ventral posterior (posteromedial, posterolateral) |
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What nuclei are in the central intralaminar nuclei?
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Centromedial nucleus
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List the specific relay nuclei.
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Ventral posterolateral nuclei
Ventral posteromedial nuclei Medial geniculate nuclei Lateral geniculate nuclei Ventral Anterior nuclei Ventral lateral nuclei |
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What are specific nuclei?
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They receive general information and evoke a sharp, localized response in the ipsilateral hemisphere.
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What are relay nuclei?
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They receive specific ascending tracts and project to cortical areas
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What are the two divisions of the ventral posterior nuclei?
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Ventral posterior lateral nuclei
Ventral posterior medial nuclei |
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What is the role of the ventral posterior nuclei?
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Receive ascending somatic sensory fibers
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What fibers are received by the VPL?
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Somatosensory from the contralateral body (DC/ML and ALS)
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What fibers are received by the VPM?
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Receives trigeminal thalamic fibers from the spinal trigeminal tract (Pain and temperature from face) and chief sensory nucleus of V1 and also gustatory fibers from nucleus solitarius.
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Where do the ventral posterior nuclei project?
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The VPL and VPM project to the primary sensory area in the posterior central gyrus and paracentral gyrus.
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From where does the VA receive fibers?
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Corpus striatum
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From where does the VL receive fibers?
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Cerebellum vi the dentato-rubro-thalamic tract
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To where do the VA and VL nuclei project?
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Both project to the motor cortex (precentral gyrus and premotor area) and contribute to initiation, organization, and control of movement.
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Describe the circuit (Papez circuit) of neurons connecting the anterior nuclei of the right dorsal thalamus to the cingulate gyrus.
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Anterior nuclei of the right dorsal thalamus project via the anterior limb of the internal capsule to the splenius of the cingulate gyrus.
The bodies in the cingulate gyrus project axons along the gyrus, out to the hippocampus where they synapse Axons project from the hippocampus via the fornix back to the anterior nuclei of the right dorsal thalamus (or synapse on the mammillary bodies, which then project to the anterior nuclei of the right dorsal thalamus) |
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What is the limbic system?
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The edge between the diencephalon and telencephalon. Concerned with basic emotions related to survival of species (fear, anger, reproduction, feeding, may be involved in memory)
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From what areas does the anterior nucleus receive input?
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Receives from the hippocampus (via fornix) and hypothalamus (via mammillothalamic tract).
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To where does the anterior nucleus project?
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It projects through the anterior limb of the internal capsule to the cingulate gyrus.
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What limbic-system characteristics are associated with the anterior nucleus?
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Involved in emotional drives, instinctive behaviors, memorization.
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What nuclei are included in the "specific association nuclei"
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Dorsomedial nucleus
Pulviner nucleus Lateral Posterior nucleus Lateral Dorsal nucleus |
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Describe the dorsomedial nucleus (including afferents and role in the brain)
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The DM is the largest nucleus in the medial thalamic region - highly developed, it receives afferents from other thalamic and hypothalamic nuclei, integrates somatic and visceral afferents, reciprocal connections with prefrontal cortex - so it is associated with mood and emotional balance. Feelings of euphoria or depression may result from stimulation of this nucleus.
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What results from the dorsomedial nucleus' connection to the hypothalamus?
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Visceral response to emotion may result - such as bad emotions causing vomiting or stomach upset.
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What would result from damaging the dorsomedial nucleus?
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Results in personality change, affects intelligence, emotional drive, memory, psychological reactions to pain (similar to prefrontal cortex damage)
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What connection, relevant to the thalamus, is cut from a frontal lobotomy?
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It severs the connection between the prefrontal cortex and dorsomedial nucleus.
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From where does the dorsal tier of the lateral nuclei receive axons?
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They receive from the ventral tier
Also the dorsal tier has reciprocal connections in the parietal, occipital and temporal lobes. |
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What is the role of the dorsal tier of the lateral nuclei?
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It is involved in analysis and integration of sensory input - particularly the Pulvinar.
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What is the role of the Pulvinar? Also where does it receive fibers and project to?
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It receives from the LGN and spinal cord
It projects to the visual association cortex and is important for visual discrimination and ability to interpret written symbols. It projects to temporal, parietal, and frontal for visual function and eye movements. |
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What region of the thalamus is important for visual discrimination and ability to interpret written symbols?
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The Pulvinar and the Lateral Posterior nucleus, both in the dorsal tier of the lateral nuclei
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Where does the lateral posterior nucleus project?
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The LP projects to the parietal, occipital, and temporal cortex - it is important for visual discrimination and ability to interpret written symbols
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Where does the Lateral Dorsal nucleus project?
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The LD projects to the cingulate gyrus (limbic system)
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Which of the specific association nuclei are associated with the limbic system?
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The Lateral Dorsal nucleus
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Which of the specific association nuclei are associated with the thalamic nuclei and cortex?
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Dorsomedial nuclei
Pulvinar Lateral posterior nuclei |
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What are the nonspecific nuclei?
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Intralaminar nuclei (centromedian)
Midline nuclei |
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What is the role of the nonspecific nuclei?
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Their role is to evoke widespread activity in both hemispheres concerned with correlation and interpretation of information
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Describe the Intralaminar nuclei, including afferents and efferents.
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The internal medullary lamina encloses several nuclei - the largest being the centromedian/intralaminar nucleus.
receives afferents from the reticular activating system and ascending pain pathways. They project to thalamic nuclei and corpus striatum. Evoke arousal response, consciousness, alertness, and awareness of pain. |
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Describe the midline nuclei.
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It is small in humans, located on wall of the third ventricle. Receives visceral afferents and projects to the hypothalamus.
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What are the reticular nuclei?
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A thin sheet between external medullary lamina and internal capsule. Gates responses of thalamic neurons to cortical input.
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What nuclei moderate thalamic input?
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Reticular nuclei
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What are the three regions of the internal capsule?
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Anterior limb
Genu Posterior limb |
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What is the internal capsule?
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Between the dorsal thalamus and the lentiform nuclei.
Consists of ascending and descending tracts that connect the thalamus and cerebral cortex. Ascending: leave the thalamus, go through the internal capsule to the corona radiata, to the cortex Descending: leave the cortex, go through the corona radiata, to the internal capsule |
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What is the hypothalamus, what influences it?
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Composed of several nuclei, located beneath the third ventricle. Influenced by factors like osmotic pressure, temperature, and hormones as conveyed by circulatory system.
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What is the role of the hypothalamus?
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Synthesizes hormones
Regulates ANS, body temperature, biological clock, anterior pituitary (by production of releasing factors) Controls electrolyte balance, emotional behavior, motivational arousal Endocrine functions - releases oxytocin and vasopressin to general circulation via posterior pituitary. |
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What is the endocrine function of the hypothalamus?
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Releases oxytocin and vasopressin to general circulation via posterior pituitary
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What is regulated by the hypothalamus?
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ANS
Body temperature Biological clock Anterior pituitary by production of releasing factors |
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What is controlled by the hypothalamus?
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Electrolyte balance
Emotional behavior Motivational arousal |
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Describe the location of the hypothalamus.
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It forms the lower and lateral wall, and floor, of the third ventricle
It is posterior to the lamina terminalis, extends posterior to and includes the mammillary bodies The median eminence is right behind the optic chiasm and attaches the infundibulum to the pituitary gland. |
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What are the three zones of the hypothalamus?
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Lateral - extends rostral-caudal and is separated from the medial zone by the fornix
Medial - rostra-caudal and has three zones: chiasmatic, tuberal, and mammillary Periventricular - all neurons that border the ependymal surfaces of the 3rd ventricle Periventricular |
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Which hypothalamic nuclei/area is considered the feeding center?
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The lateral area
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Which hypothalamic nuclei/areas are considered the satiety center?
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Dorsomedial nucleus
Ventromedial nucleus |
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Which hypothalamic nuclei/area is considered the reproductive area?
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Preoptic area
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Which hypothalamic nuclei/area is the area that controls circadium rhythms?
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Suprachiasmatic nucleus
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Which parts of the hypothalamus have neuroendocrine functions?
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Tuber cinereum
Median eminence Posterior pituitary |
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Which nuclei are visible on a coronal section through the hypothalamus?
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Below the thalamus, begins the hypothalamus:
Paraventricular nuclei (bilateral) Lateral nuclei (bilateral, lateral to anterior nuclei) Anterior nuclei (bilateral) Ventromedial nuclei (bilateral) Tuber cinereum |
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List the major afferent connections to the hypothalamus.
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Olfactory
Limbic cortical centers Frontal cortex Environmental light Peripheral influences Sensory input |
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Trace out the limbic cortical center afferent fibers received by the hypothalamus.
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Hippocampus --> fornix --> hypothalamus
Amygdala --> Stria terminalis --> hypothalamus |
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Trace out the frontal cortex afferent fibers received by the hypothalamus.
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Frontal cortex (septal area) --> medial forebrain bundle --> hypothalamus
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What is the role of environmental light in influencing the hypothalamus?
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It drives metabolic and hormonal activity
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What are some peripheral factors that influence the hypothalamus?
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Osmotic pressure
Plasma glucose levels Gonadal steroid levels Blood temperature |
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What kind of sensory input is received by the hypothalamus?
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Via spinal cord and brainstem (reticular formation), afferent pathways (taste, pain, general tactile)
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Name the two major descending pathways from the hypothalamus.
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Dorsal longitudinal fasciculus
Mammillotegmental fasciculus |
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Name the major ascending pathway of the hypothalamus.
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Mammillothalamic tract
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Describe the path and innervations of the dorsal longitudinal fasciculus.
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It runs beneath the ventricular system through the brainstem - some fibers may innervate brainstem nuclei (dorsal nucleus of vagus) and some fibers continue into the spinal cord to terminate in the intermediolateral cell column.
Brainstem PANS Spinal cord SANS |
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Describe the path and innervations of the mammillotegmental fasciculus.
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Collateral branches of the mammillothalamic tract descend and terminate in reticular formation nuclei in the midbrain and pons.
Project to midbrain; pontine tegmental reticular formation. |
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Describe the path of the mammillothalamic tract.
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It projects from the mammillary bodies to the anterior nucleus of the dorsal thalamus.
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Describe the input from the prefrontal cortex into the hypothalamus.
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Prefrontal cortex, via dorsomedial thalamic tract, sends input about emotions, moods, personality
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Describe the input from the ascending visceral afferent into the hypothalamus.
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Provides input such as taste and pain
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What kind of input is received by the hypothalamus from the limbic system?
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Fear, anger, pleasure, sex
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What are some projections from the hypothalamus?
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Edinger-Westphal nucleus - CN III - pupillary constriction
IML - to superior cervical ganglion - pupillary dilation Facial nucleus - VII - facial expressions Superior salivary nucleus - lacrimation Inferior salivary nucleus - salivation Brainstem respiratory centers Brainstem cardiac centers - dorsal motor nucleus of vagus and nucleus ambiguus - PANS pressor and depressor centers Spinal cardiac centers - IML - SANS preganglionic Dorsal motor nucleus of vagus - PANS for gut and other viscera Spinal cord IML - SANS for gut and other viscera |
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What is the highest center for coordination of visceral activity of the autonomic nervous system?
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Hypothalamus
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What are the two principle centers of visceral function control by the hypothalamus?
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Parasympathetic nervous system (Anterior, Medial hypothalamus)
Sympathetic nervous system (Posterior, Lateral hypothalamus) |
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What results from stimulating the PANS center of the hypothalamus?
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Decreased HR, BP
Increased peristalsis, secretion of digestive enzymes, salivation Pupillary constriction Peripheral dilation |
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What results from stimulating the SANS center of the hypothalamus?
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Increased HR, BP
Decreased Peristalsis, secretion of digestive enzymes Pupillary dilation Peripheral vasoconstriction Piloerection (goosebumps) |
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What two regions of the hypothalamus control temperature regulation?
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Anterior and posterior hypothalamus
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What is the role of the anterior hypothalamus as far as temperature regulation?
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Heat dissipation center - increased blood temperature causes cells to discharge to lower brain centers to initiate sweating and cutaneous dilation
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What is the role of the posterior hypothalamus as far as temperature regulation?
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Heat conservation center - decreased blood temperature causes cells to discharge to lower centers to initiate vasoconstriction, shivering, and increased visceral activity to promote heat production and conservation.
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What areas of the hypothalamus govern food intake?
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Satiety center, in or near the ventromedial nucleus
Feeding center, in the lateral hypothalamus |
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What would result from a lesion near or in the ventromedial nucleus?
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Hyperphagia - overeating - obesity
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What would result from a lesion on the lateral hypothalamus?
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Anorexia - loss of desire to eat
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What regions of the hypothalamus are involved in the sleep-wake cycle?
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Anterior hypothalamus - sleep cycle
Posterior hypothalamus, mammillary bodies - wake cycle |
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What regions of the hypothalamus are involved in water balance?
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Supraoptic, Paraventricular nuclei
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name the Nonselective α-blockers
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Phenoxybenzamine (irreversible)
phentolamine (reversible) |
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What part of the hypothalamus is related to reproduction and growth?
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Preoptic nucleus (medial preoptic area) - controls release of LH and FSH - sexually dimorphic area, different cell sizes.
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Where are magnocellar neurons located?
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Paraventricular and supraoptic nuclei
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What is the role of magnocellar neurons?
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They have varicosed axons that project to the neurohypophysis - they contain the neurosecretory hormones oxytocin or vasopressin. When stimulated they release oxytocin or vasopressin into the capillary beds i the neurohypophysis and into general circulation.
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What hormones are released via magnocellar neurons?
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Oxytocin
Vasopressin |
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What is the role of Oxytocin?
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Uterine contractions
Milk ejection Maternal and mating behaviors Penile erection Orgasm |
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What is the role of vasopressin?
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Also called ADH - necessary for water reabsorption
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Where are parvocellular neurons?
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In the tuberal region of the hypothalamus that project into the neurohemal zone of the median eminence
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What is released by parvocellular neurons?
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Hypothalamic Hypophysiotropic Hormones (HHH)
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List some HHHs
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Corticotropin-releasing hormone
Growth hormone release hormone Growth hormone inhibitory-release hormone (somatostatin) Thyrotropin releasing hormone Prolactin inhibiting hormone (dopamine) Prolactin releasing hormone Gonadotropin releasing hormone Follicle stimulating hormone releasing hormone Luteinizing hormone releasing hormone |
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List some adenohypophysial hormones
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Adrenocorticotropic hormone (ACTH)
Growth hormone (somatotropin) Thyrotropic hormone (TSH) Prolactin Follicle stimulating hormone Luteinizing hormone |
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What is the role of HHH?
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It is released into the capillary bed formed by the superior hypophysial arteries in neurohemal zone - hormones are transported by portal veins to the venous sinusoids of the adenohypophysis. There HHH stimulates or inhibits the release of adenohypophysial trophic hormones. This vascular system i called the hypothalamohypophysal portal system.
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What is the clinical correlation related to the location of the hypophysis?
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The hypophysis is located at the center of a spread of nerves and arteries (CN III, CN IV, CN V1, CN V2, CN VI, internal carotid arteries, optic chiasm, anterior cerebral arteries)
As a result, a tumor could expand to cause visual deficits, problems with eye movements, and sensory loss to the face (plus hormone release problems). |
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What is the triad of symptoms associated with pituitary tumor?
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Diabetes insipidus
Visual deficits Panhypopituitarism |
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From where do pituitary tumors specifically originate?
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Usually from the anterior pituitary (adenohypophysis)
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What are the three parts of the subthalamus?
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Subthalamic nucleus
Prerubral field Zona incenta |
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Where is the subthalamus located?
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Between midbrain and diencephalon - ventral and caudal to dorsal thalamus. Red nucleus extends into it - functionally related to motor system.
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Describe the shape, effects, and blood supply of the subthalamic nucleus.
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Shaped like a biconvex lens
Has an excitatory effect on the globus pallidus Supplied by.. Posterior cerebral artery Posterior communicating artery |
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A lesion in what area of the diencephalon would cause contralateral hemiballism?
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Lesion to the subthalamic nucleus, within the subthalamus
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Where is the prerubral area and what fibers does it carry?
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It is rostral to the red nucleus
Carries fibers from the lenticular and thalamic fasciculus |
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Where is the zona incenta and what fibers does it carry?
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Zona incenta is located posterior to the subthalamic nucleus
Receives motor information and sends projections to the cortex and brainstem |
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Where is the epithalamus located?
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Posteriorly in the diencephalon roof
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What nuclei, tracts, etc. are contained within the epithalamus?
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Habenular nuclei
Pineal gland Habenular commissure Stria medullaris thalami Posterior commissure |
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What systems are associated with the habenular nuclei?
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Olfactory and limbic systems
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What is the role of the habenular commissure?
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It allows crossing of fiber tracts (stria medullaris thalami) from one habenular nucleus to another
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What is the role of the stria medullaris thalami?
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It carries a fiber tract that originates in the septal area (olfactory, limbic) and projects to habenular nuclei
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What is the posterior commissure?
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A region consisting of connections of the medial longitudinal fasciculus, interstitial nuclei, superior colliculus, pretectal nuclei
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Where is the pineal gland?
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It overhangs the superior colliculus, below the splenium of the corpus callosum. The great cerebral vein is located between the splenium and the pineal gland.
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What are the two stalks of the pineal gland?
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Lower stalk - connects to the posterior commissure
Upper stalk - connects to the habenular commissure |
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What kinds of cells are found in the pineal gland?
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Glial cells
Pinealocytes (NO TRUE NEURONS) |
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What hormone related to the sleep-wake cycle is produced by the pineal gland?
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Melatonin is produced from serotonin - the maximum secretion is in darkness - the effect of light is via retina to the suprachiasmatic nuclei of the hypothalamus, to the IML to the superior cervical ganglion, to the pineal gland.
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What are some clinically relevant things about the pineal gland?
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Pineal gland is an endocrine gland, it exerts anti-gonadotropic effects on the hypothalamus and anterior/posterior pituitary.
Pinealoma - tumor with large numbers of pinealocytes - decreases gonadal function = delayed puberty Expanding pinealoma - compresses pretectal region and superior colliculi, producing fixed dilated pupil and paralysis of upward gaze. |
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What would result from a lesion in the pineal gland?
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Loss of pineal cells - precocious puberty
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Why can the pineal gland be used as a midline marker by radiologists?
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After puberty, calcareous deposits called "brain sand" (by-product of secretory activity) are present in the pineal gland - this allows for the pineal to be seen on xray.
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What arteries supply the dorsal thalamus?
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The medial and lateral posterior choroid arteries, which branch from the middle and posterior cerebral arteries
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What arteries supply the hypothalamus?
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Branches of the circle of willis and the posterior cerebral artery
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What arteries supply the anterior hypothalamus?
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The central branches of the anterior communicating artery, the anterior cerebral artery, and the proximal part of the posterior communicating artery.
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What arteries supply the caudal and ventral hypothalamus?
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Posterior communicating artery
Posterior cerebral artery |
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What is thalamic syndrome?
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A vascular lesion in the thalamus, usually VPL or VPM (sometimes involving the posterior limb of the internal capsule).
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What are the signs of thalamic syndrome?
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Loss of sensation on contralateralside - with recovery. Pain is diffuse and constant on contralateral body - light stimuli trigger pain.
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What would result from a lesion in the posterior limb of the internal capsule?
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Blood supply to the internal capsule is from the lateral striate arteries (from middle cerebral artery). The lesion produces an upper moor lesion of the contralateral body (hemiplegia) - sometimes with partial sensory loss.
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