thalamus Flashcards
situated at the rostral end of the brain- stem and functions as an important relay and integrative station for information passing to all areas of the cerebral cortex, the basal ganglia, the hypothalamus, and the brainstem
thalamus
narrow and rounded and forms the posterior boundary of the interventricular foramen
anterior end of the thalamus
expanded to form the pulvinar, which overhangs the superior colliculus
posterior end
continuous with the tegmentum of the midbrain
inferior surface
forms part of the lateral wall of the third ventricle and is usually connected to the opposite thalamus by a band of gray matter, the interthalamic connection
medial surface of the thalamus
thalamus is covered on its superior surface by a thin layer of white matter, called the ___, and on its lateral surface by another layer, the ___
stratum zonale; external medullary lamina
- gray matter of the thalamus is divided by a vertical sheet of white matter, the ___, into medial and lateral halves
- consists of nerve fibers that pass from one thalamic nucleus to another
internal medullary lamina
lies between the limbs of the Y
anterior part
lie on the sides of the stem of the Y
medial and lateral parts
- anterior part of the thalamus contains the ___
- receive the mammillothalamic tract from the mammillary nuclei
- receive reciprocal connections with the cingulate gyrus and hypothalamus
anterior thalamic nuclei
function of the ___ limbic system and is concerned with emotional tone and the mechanisms of recent memory.
anterior thalamic nuclei
- medial part of the thalamus contains the large ___
- two-way connections with the whole prefrontal cortex of the frontal lobe of the cerebral hemisphere
- interconnected with all other groups of thalamic nuclei
dorsomedial nucleus
integration of a large variety of sensory information, including somatic, visceral, and olfactory information, and the relation of this information to one’s emotional feelings and subjective states
medial part of the thalamus
- lateral dorsal nucleus, the lateral posterior nucleus, and the pulvinar
- have interconnections with other thalamic nuclei and with the parietal lobe, cingulate gyrus, and occipital and temporal lobes.
dorsal tier
- connected to the reticular formation, the substantia nigra, the corpus striatum, and the premotor cortex
- influences the activities of the motor cortex
Ventral anterior nucleus
- major input from the cerebellum and a minor input from the red nucleus
- main projections pass to the motor and premotor regions of the cerebral cortex
- influences motor activity
Ventral lateral nucleus
nucleus is subdivided into the ventral posteromedial nucleus and the ventral posterolateral nucleus
Ventral posterior nucleus
receives the ascending trigeminal and gustatory pathways
ventral posteromedial nucleus
receives the important ascending sensory tracts, the medial and spinal lemnisci
ventral posterolateral nucleus
thalamocortical projections from these important nuclei pass through the posterior limb of the internal capsule and corona radiata to the primary somatic sensory areas of the cerebral cortex in the postcentral gyrus
Ventral posterior nucleus
- small collections of nerve cells within the internal medullary lamina
- receive afferent fibers from the reticular formation as well as fibers from the spinothalamic and trigeminothalamic tracts
- influence the levels of consciousness and alertness in an individual
intralaminar nuclei
- consist of groups of nerve cells adjacent to the third ventricle and in the interthalamic connection
- receive afferent fibers from the reticular formation
- precise functions are unknown
midline nuclei
- thin layer of nerve cells sandwiched between the external medullary lamina and the posterior limb of the internal capsule
- concerned with a mechanism by which the cerebral cortex regulates thalamic activity
reticular nucleus
forms part of the auditory pathway and is a swelling on the posterior surface of the thalamus beneath the pulvinar
medial geniculate body
- Afferent fibers to the medial geniculate body form the ___ and come from the inferior colliculus
- receives auditory information from both ears but predominantly from the opposite ear
inferior brachium
- forms part of the visual pathway and is a swelling on the undersurface of the pulvinar of the thalamus
- receives visual information from the opposite field of vision
lateral geniculate body
made up of complicated collections of nerve cells that are centrally placed in the brain and are interconnected
thalamus
A vast amount of sensory information of all types (except ___) converges on the thalamus and presumably is integrated through the interconnections between the nuclei
smell
first integrated at a lower level with taste and other sensations and is relayed to the thalamus from the amygdaloid complex and hippocampus through the mammillothalamic tract
olfactory information
required for the interpretation of sensations based on past experiences
cerebral cortex
ventroanterior and the ventrolateral nuclei of the thalamus form part of the basal nuclei circuit and thus are involved in the performance of ___
voluntary movements.
has extensive connections with the frontal lobe cortex and hypothalamus
large dorsomedial nucleus
- closely connected with the activities of the reticular formation, and they receive much of their information from this source
- control the level of overall activity of the cerebral cortex
- able to influence the lev- els of consciousness and alertness in an individual
intralaminar nuclei
All types of sensory information, with the exception of smell, reach the thalamic nuclei via ___
afferent fibers
The cerebellar—rubro—thalamic—cortical—ponto—
cerebellar neuron pathway is important in ___
voluntary movement
the projections of the ventral posterolateral nucleus ascend to the postcentral gyrus through the posterior limb of the ___
internal capsule
The ___ receives auditory information from both ears but predominantly from the opposite ear
medial geniculate body
Each ___ receives visual information from the opposite field of vision
lateral geniculate body
area of white matter lying on the lateral surface of the thalamus
external medullary lamina
subdivides the thalamus into three main parts
Y—shaped internal medullary lamina
receives the ascending trigeminal and gustatory pathways
ventral posteromedial nucleus
receives auditory information from the inferior colliculus and from the lateral lemniscus
medial geniculate body
- receives most of the fibers of the optic tract
- has a nucleus made up of six layers of nerve cells
lateral geniculate body
- Mammillothalamic tract, cingulate gyrus, hypothalamus
- Cingulate gyrus, hypothalamus
- Emotional tone, mechanisms of recent memory
Anterior
- Prefrontal cortex, hypothalamus, other thalamic nuclei
- Prefrontal cortex, hypothalamus, other thalamic nuclei
- Integration of somatic, visceral, and olfactory information and relation to emotional feelings and subjective states
Dorsomedial
- Cerebral cortex, other thalamic nuclei
- Cerebral cortex, other thalamic nuclei
Lateral dorsal, lateral posterior, pulvinar
- Reticular formation, substantia nigra, corpus striatum, premotor cortex, other thalamic nuclei
- Influences activity of motor cortex
Ventral anterior
- As in ventral anterior nucleus but also major input from cerebellum and minor input from red nucleus
- Influences motor activity of motor cortex
Ventral lateral
- Trigeminal lemniscus, gustatory fibers
- Primary somatic sensory (areas 3, 1,and 2) cortex
- Relays common sensations to consciousness
Ventral posteromedial (VPM)
- Medial and spinal lemnisci
- Primary somatic sensory (areas 3, I, and 2) cortex
- Relays common sensations to consciousness
Ventral posterolateral (VPL)
- Reticular formation, spinothalamic and trigeminothalamic tracts
- To cerebral cortex via other thalamic nuclei, corpus striatum
- Influences levels of consciousness and alertness
intralaminar
- Reticular formation
Midline
- Cerebral cortex, reticular formation
- Other thalamic nuclei
- Cerebral cortex regulates thalamus
Reticular
- Inferior colliculus, lateral lemniscus from both ears but predominantly the contralateral ear
- Auditory radiation to superior temporal gyrus
- Hearing
Medial geniculate body
- Optic tract
- Optic radiation to visual cortex of occipital lobe
- Visual information from opposite field of vision
Lateral geniculate body
A patient exhibits a variety of behavioral and language problems such as a failure to inhibit responses that are socially inappropriate. Such an individual is most likely to suffer from dementia involving the:
Frontal cortex
The corpus callosum of each of 20 patients was severed in order to reduce the spread of seizure activity. The patients were then asked to participate in a research study to identify specific features of brain function. The most likely purpose of this study was to:
Identify the various properties of cerebral dominance
A patient exhibits clumsiness, weakness, and somatosensory loss of the right leg. The most likely cause of these symptoms is a:
Hemorrhagic stroke of the left anterior cerebral artery
A 68-year-old man is admitted to the emergency room (ER) after initially complaining of dizziness. In the ER, the patient indicated that he could not move his right arm or leg, and his speech was slurred. The tongue was directed to the right side when the patient was asked to protrude it, and the patient’s jaw drooped to the right side as well. Sensory functions on each side of the body appeared normal as well as motor functions on the left side.
The patient suffered a stroke involving the:
Middle cerebral artery
A 68-year-old man is admitted to the emergency room (ER) after initially complaining of dizziness. In the ER, the patient indicated that he could not move his right arm or leg, and his speech was slurred. The tongue was directed to the right side when the patient was asked to protrude it, and the patient’s jaw drooped to the right side as well. Sensory functions on each side of the body appeared normal as well as motor functions on the left side.
The stroke involved the:
Left internal capsule
