Exam 2- week 7 ppt 8 Diencephalon: Thalamus Flashcards
What are 4 major subdivisions of the diencephalon?
~thalamus
~hypothalamus
~epithalamus
~subthalamus
Quick info on hypothalamus
endocrine, autonomic, and limbic functions
Quick info on thalamus
centrally located relay and association nuclei
Quick info on epithalamus
pineal gland and associated structures
Quick info on subthalamus
one of the basal nuclei (ganglia)
thalamus has relations to
~subthalamus
~red nucleus
~substantia nigra
~zona incerta
Where are the subthalamus, red nucleus and substantia nigra located in relation to the thalamus?
all postero-inferior to the thalamus
Where is the zona incertra in relation to the thalamus?
~contiguous with a part of the thalamus – a nucleus called the thalamic reticular nucleus
~also inferior to the thalamus
the thalamus has ______ nuclei and _____ nuclei
~sensory relay nuclei
~motor relay nuclei
Sensory relay nuclei of the thalamus
~All sensory pathways except olfaction relay in thalamus prior to entering cerebral cortex
~Located in posterior (caudal) thalamic nuclei
Motor relay nuclei of the thalamus
~Way for basal nuclei (ganglia) & cerebellum to communicate with cerebral cortex
~Located in anterior (rostral) thalamic nuclei
The nuclei are topographically organized into _ regions by
into 3 regions or sets of nuclei by sheets of myelinated axons that form internal medullary lamina
What are the 3 major regions for the nuclei?
~anterior nuclei
~lateral nuclei
~medial nuclei
Medial nuclei of the thalamus
~Dominated by dorso-medial nucleus (DM)
~Midline nuclei which line ventricular surface
Lateral nuclei of the thalamus
~composed of a Dorsal tier and a Ventral tier
Dorsal lateral nuclei of the thalamus
include:
~Lateral dorsal
~Lateral posterior
~Pulvinar (the large posterior positioned nucleus)
Ventral lateral nuclei of the thalamus
consist of:
~Ventral anterior (VA)
~Ventral lateral (VL)
~Ventral posterior (VP)
Ventral posterior nucleus is composed of two separate nuclei ~Ventral Posterior Lateral (VPL) ~Ventral posteror Medial (VPM) nuclei. ~Lateral geniculate body (or nucleus) ~Medial geniculate body (or nucleus)
Two other nuclei in the thalamus
~interlaminar nuclei
~reticular nuclei
Interlaminar nuclei of the thalamus
~within the Internal medullary lamina splits the thalamus dorsally & ventrally
~Centromedian nucleus is ventrally positioned
~lateral dorsal nucleus is dorsally positioned
~small interlaminar nuclei in between the two larger nuclei
Reticular nucleus of the thalamus
~located external to the thalamus – just medial to internal capsule
~plays an important role in regulating the excitability of other thalamic nuclei
where is the zona incerta located?
~located ventral to thalamus
~contiguous with reticular nucleus
Zona incerta details
~has a wealth of interconnections with brainstem, cerebellum, cerebrum, thalamus & hypothalamus
~has a role in integrating these inputs through the thalamus
Zona incerta details on the role in integration
~play roles in the Integration of subcortical & cortical electrical rhythms
~of sensorimotor & visceral/limbic activity
~of diverse sensory channels to appropriate visceral, arousal, attention and posture-locomotion responses
Thalamus has major functions in ____ and____ integration
~sensory
~motor
Sensory integration in the thalamus
~with exception is olfactory input
~Receives, processes and forwards sensory information to the sensory cerebral cortex
~Recognition of affective quality of the sensation
Motor integration in the thalamus
integration of cerebellar & basal nuclei (ganglia) input to motor cortex
Internal organization of the thalamus
~Composed of projection & interneurons with about 75% of neurons projection neurons & most project to cerebral cortex
Details on the Primary Gateway to Cortex
~most input to cerebral cortex via thalamus
Atain exceptions include:
~Olfactory inputs
~number of Diffuse cholinergic & monoaminergic inputs to the forebrain from the brainstem which are part of the generalized role of the reticular activating system
What are the two major forms of input for the thalamus?
~specific input
~regulatory input
Specific input for the thalamus
~composed of specific sensory and motor Relay information each from specific source to a specific area of cortex
~all topographically organized at all points in the relay: inputs, thalamic nuclei & cortex
~ascending somatosensory tracts (DC/ML & ALS) are somatopically organized (information from each region of the body is mapped to specific areas of the tract)
~the thalamus is somatopically organized with information from the hand & arm are more medial and information from the leg and feet are more lateral in the ventral posterior lateral (VPL) nucleus and the face Trigeminothalamic input to the ventral posterior medial (VPM) nucleus
~project up to the somatosensory cortex where the face is more ventral-laterally positioned and the legs and feet more dorsomedially positioned along the post-central gyrus.
Regulatory input for the thalamus
~far outnumber specific inputs and control whether specific inputs are transmitted thru the thalamus to cortex
~regulatory inputs come from the cerebral cortex from the same areas to which specific input its projecting
~input from the somatosensory cortex regulates the input through the ventral posterior lateral and ventral posterior medial nuclei
~regulatory input comes from the reticular nucleus of thalamus
Specific relay nuclei of the thalamus
Receive specific inputs from well-defined tracts and project to (and receive fibers from) specific cortical areas: sensory, motor, or limbic
Association nuclei of the thalamus
Input from and output to sensory association and limbic cortices
Diffuse projection nuclei of the thalamus
a wide variety of connections To and from spinal cord, basal nuclei, cerebellum, frontal & parietal cortex
Regulatory nucleus of the thalamus
reticular nucleus
Relay sensory- VPL- principal input and cortical output
~Medial Lemniscus and spinothalamic tracts
~somatosensory cortex- postcentral gyrus
Relay sensory- VPM- principal input and cortical output
~trigeminothalamic tract
~somatosensory cortex- postcentral gyrus
Relay sensory- MGB- principal input and cortical output
~auditory via inf colliculus
~auditory cortex- superior temporal gyrus
Relay sensory- LGB- principal input and cortical output
~visual via optic tract
~visual cortex- occipital lobe
Relay motor- VA- principal input and cortical output
~basal nuclei
~motor cortex- frontal lobe
Relay motor- VA- principal input and cortical output
~cerebellum
~motor cortex- frontal lobe
Relay Limbic- A- principal input and cortical output
~mamillothalamic tract and hippocampus
~limbic cortex- cingulate gyrus
Relay Limbic- LD- principal input and cortical output
~hippocampus
~limbic cortex- cingulate gyrus
Association Sensory- P- principal input and cortical output
~parietal, temporal, occipital lobes and visual system
~parietal, temporal, and occipital lobes and visual system
Association Sensory- LP- principal input and cortical output
~parietal lobe
~parietal lobe
Association Limbic- DM- principal input and cortical output
~prefrontal cortex, olfactory and limbic structure (amygdala)
~prefrontal cortex
Diffuse cortically projecting- IL- principal input and cortical output
~frontal and parietal cortex, basal nuclei, cerebellum, spinal cord, and reticular formation
~widespread areas of cerebral cortex and striatum of basal nuclei
Diffuse cortically projecting- CM- principal input and cortical output
~frontal and parietal cortex, basal nuclei, cerebellum, spinal cord, and reticular formation
~widespread areas of cerebral cortex and striatum of basal nuclei
Regulatory- R- principal input and cortical output
~collateral of thalamocortical and cortiothalamaic axons
~none- intra-thalamic
Thalamic syndrome
~Typically caused by occlusion of thalamogeniculate branches of the PCS supplying posterior thalamus
~Symptoms contralateral to lesion
~Hemianesthesia
~Dysesthesia
~Ataxia
~Excruciating neurogenic pain which is unresponsive to analgesics
~treated by anticonvulsants or other drugs used for treating peripheral neuropathies
