Unit 5 - Subcortical Nuclei Flashcards
Name the 3 basal ganglia
Caudate
Putamen
Globus pallidus
What are the basal ganglia derived from
The telencephalon, which is said to have a pallital and subpallital area early on
2ndary vesicles that expand bilaterally to form the cerebral hemispheres
Components of diencephalon
Thalamus
Hypothalamus
Epithalamus
Metathalamus
Subthalamus
Pallidal area of telencephalon gives rise to
Cerebral cortex
Subpallidal area of telencephalon gives rise to
Basal ganglia, basal forebrain and cholinergic system
What is the line of fusion between the telencephalon and diencephalon
Internal capsule
Between basal ganglia and thalamus
Epithalamus
String of associated structures superior and posterior to the thalamus on the midline
Metathalamus
2 prominences on the posterior surface of thalamus responsible for vision and hearing
Subthalamus
Closely related to basal ganglia
Cephalic extension of midbrain
Medial view of saggital section
Embryology of telencephalon and diencephalon
Striatum =
Caudate and putamen
Nucleus accumbens is
Where an inferior anterior region of caudate is continuous with the putamen
Major input of striatum
Receiving majority of afferents from cerebral cortex
Corticostriatal fibres - excitatory - glutaminergic
Input from thalamus and substantia nigra - dopaminergic
input from ventral tegmental area, origin area for dopaminergic neurons, and from raphae nuclei in pons and midbrain, origin area for serotinergic neurons
Striatal efferents
tend to be GABA neurons (inhibitory) and send signals to GP
Striatopallidal fibres
What is the nucleus accumbens implicated in
NA - processes reward and identified clinically in ahadonia - inability to enjoy things
Also in addiction
Relationship between caudate, thalamus and lentiform
What does the nucleus accumbens connect to
Amygdala in limbic system, w/ the basal ganglia - dopaminergic neurons involved in reward, gratification and addiction
hence site of action of addictive substances
What does GPi share connections with
Subthalamus
Pars reticulata of substantia nigra in midbrain/upper brainstem
What is the GP a major output portion of
Basal ganglia
Where do pallidal afferents come from
What is their nature
Subpallidal nucleus (blue) from subthalamonigral and subthalamopallidal pathways
Often glutaminergic
Excitatory
Where do pallidal efferents travel
Leave GPe and travel to subthalamic nucleus, leave GPi and pars reticulata of substantia nigra and go to thalamus - pallidothalamic pathway - and travel to brainstem tegmentum, pedunculopontine nucleus for MOVEMENT
What nuclei are found in the metathalamus
Medial and lateral geniculate nuclei
Components of diencephalon
Thalamus
Hypothalamus
Epithalamus
Metathalamus
Subthalamus
What forms the roof of the 3rd ventricle
Thalami nuclei
What forms the boundary walls of the 3rd ventricle
Medial surface of 2 thalami nuclei
What does the thalamus act as
The relay station for all ascending pathways on their route to the cerebral cortex
What is in the internal medullary lamina
Contains intralaminar nuclei involved in wakefulness - connected to ascending reticular system originating in the brainstem
It activates the cerebral mantle - alpha rhythm associated with repose and sleep
What happens with lesions of the thalamus
Reduced perception of pain and in level of consciousness
What is the anterior nucleus involved with
Limbic system
Afferents from mamillary bodies via mamillothalamic tract
efferents from cingulate in control of instinctive drives
Function of ventral tier of lateral group (thalamus)
project to discrete cortical areas eg primary sensory and motor cortices - movement through afferents from basal ganglia and SN and reciprocal connections with motor, premotor and supplementary motor cortices, sensory relays from trunk, limbs head neck - sensory determinations
What does the dorsal tier of the lateral group do
less specific - diffuse reciprocal connections with large regions of the cortex
Function of medial group
Afferents from hypothalamus, amygdala and other thalamic nuclei including intralaminar nucleus and lateral thalamic nuclei
extensive reciprocal connections with prefrontal cortex - CONTROL OF MOOD AND EMOTIONS - anterior thalamic radiations
Nuclei of hypothalamus
Preoptic
Supraoptic
Paraventricular
Posterior
What is the hypothalamus connected to
limbic system via infundibulum - connects directly to posterior pituitary (sella turcica)
Protected by sellla diaphragma
Post. pituitary derives from
Brain tissue
Ant. pituitary derives from
Roof of mouth and ascends
What is the posterior boundary of hypothalamus
Demarcated by mamillary bodies
What is the hypothalamus inferior and superior to
Hypothalamus is inferior to thalamus and superior to optic chiasm and pituitary
Structures of epithalamus, anterior to posterior
IV foramen
Choroid plexus
Habenula
Pineal gland
Posterior commissure
- epithalamus - Superior and posterior to _______
Lie superior and posterior to thalamic nuclei
Function of pineal gland
Where is it found
Melatonin (precursor of serotonin) - sleep wake cycle
Wrapped in pia and hangs down into quadrigeminal cistern, between pair of superior colliculi between the upper posterior midbrain
What is the habenula
A small nucleus that projects to the midbrain and receives connections from anterior diencephalic region - hypothalamus and from basal forebrain regions
Where is stria medullaris found
Forms a ridge on the medial surface of the medial thalamic nucleus
Relations of MG nuclei of metathalamus
Inferior colliculi
Auditory pathway
Relations of LG nuclei of metathalamus
Superior colliculi
Visual pathway
Where are the geniculate nuclei found
Paired eminences on the posterior inferior surface of the thalamus, just superior to posterior midbrain
connected via brachium/arms to colliculi of midbrain
Where do projections of the LG nuclei travel
In IC to primary visual cortex of occipital lobe
Where does the subthalamus lie
Inferior to thalamus
Superior to midbrain (substantia nigra)
* transitional zone to midbrain
involved in motor control
Overview of subcortical nuclei
What is the claustrum reclassified as
Sub-insular rather than part of the basal ganglia
