Lecture 5 - Basal Ganglia & Diencephalon Flashcards
What are the three types of white matter tracts?
We have three different types of tracts in the brain, the projection, commissural, and association tracts.
Where do the projection tracts extend?
The projection tracts extend vertically from the brain to the spinal cord
What do the projection tracts create?
The internal capsule
Where do commissural tracts cross?
From one hemisphere to the other
What is the major commissural tract?
The corpus callosum is the major commissural tract.
What are the anatomical components of the corpus callosum? (4)
The splenium, body, genu, and rostrum
Where are the rostrum and genu located and what do they connect? -of what bitch
The rostrum and genu are both located anteriorly and connect neurons in the frontal lobe. Genu is located above rostrum.
Where is the body of the corpus callosum located and what does it connect?
The body is found in the middle of the corpus callosum and it connects parts of the frontal and parietal lobe.
Where is the splenium of the corpus callosum located and what does it connect?
The splenium is the most posterior of the corpus callosum and it connects the neurons temporal and occipital lobes.
What do the association tracts connect?
Association tracts connect lobes and gyri within the hemisphere.
What is the basal ganglia?
The basal ganglia (basal nuclei) are a collection of neurons at the base of the brain
What forms the lentiform nucleus?
The putamen (superficial) and globus pallidus (deep)
What forms the corpus striatum?
The lentiform nucleus and the caudate nucleus
What are the different parts of the caudate nucleus?
The caudate nucleus has a head, body and tail.
What is found at the tail of the caudate nucleus?
At the tail of the caudate nucleus we have the amygdaloid nucleus which is part of the limbic system (not part of basal ganglia)
What makes up the diencephalon?
The diencephalon is made up of three-paired structures, the thalamus, hypothalamus, and epithalamus.
What % of the diencephalon does the thalamus make up?
80%
What ventricle is the thalamus associated with?
The thalamus is associated with the 3rd ventricle and forms its walls.
What connects the thalami?
The interthalamic adhesion (intermediate mass).
What does the anterior commissure include?
Axons that connect the middle and inferior temporal gyri of the two sides
What is the basal ganglia functionally associated with?
The subthalamic nuclei and the substantia nigra
Where is the posterior limb of the internal capsule located?
Between the lentiform nucleus and thalamus
Where is the anterior limb of the internal capsule located?
Between the lentiform and caudate nuclei
Where does the basal ganglia recieve inputs from?
The substantia nigra and motor cortex
How does basal ganglia have access to motor neurons in the cerebral cortex?
Through the thalamus as there is no direct access - hence the coritcal-basal ganglia-thalamic-cortical loop
What is the basal ganglia’s function in motor control?
Inhibition of unnecessary movements/ act as a brake
Regulate attention and cognition
How does basal ganglia influence spinal cord motor neurons?
Indirectly
What is Parkinson’s disease?
Substantia nigra dopamine neuron degeneration
What are the motor deficits found in Parkinson’s disease?
Rigidity Tremor (at rest) Difficulty initiating movement Postural instability Shuffling gait Stiff facial expression
What are possible treatments of Parkinson’s?
Replacement of dopamine
Stem cell therapy
Deep brain stimulation
What is the function of the thalamus?
The thalamus is the gateway to the cerebral cortex and its functions are to relay sensation, motor activities, cortical arousal, and memory.
Where is the hypothalamus located?
The hypothalamus is located below the thalamus and is superior to the brainstem
What seperates the thalamus and hypothalamus?
The hypothalamic sulcus
What ventricle is the hypothalamus associated with?
Third ventricle - forms the inferolateral wall of the third ventricle
What is the relationship between hypothalamus and pineal gland?
The hypothalamus has neuronal control over the pituitary gland
Where does the hypothalamus extend from?
The optic chiasma
What are the main homeostatic roles of the hypothalamus? (7)
Autonomic control centre (respiration)
Centre for emotional response (limbic system)
Body temperature regulation (thermosensitive neurons)
Regulation of food intake (appetite and satiety centres)
Regulation of water balance and thirst (thirst centre)
Regulation of sleep-wake cycle (with pineal gland)
Control of endocrine system functioning (ovaries and testes to produce either egg or sperm)
What is the epithalamus?
The epithalamus is a small, cone-shaped body that is attached to the roof of the third ventricle.
What does the epithalamus contain?
The epithalamus contains the pineal gland and has calcium salts (pineal salt) in adults (radiopaque).
What important hormone does the epithalamus produce?
The epithalamus generates melatonin.
