PBL 5 Flashcards
what hierarchies is the control of movement split into and what comes under them?
Control of movement is split into various hierarchies:
• Local Control - Spinal Cord & Cord Reflexes
• Subcortical Control - Brainstem, Basal Ganglia & Cerebellum
• Cerebral Control - Cerebral Cortex
describe the function of the supplementary motor area
It is involved in programming complex sequences of movements and coordinating bilateral movements based on mental visualisation of remembered sequences.
what makes up the corpus striatum?
made up of Caudate Nucleus, Putamen and Globus Pallidus
what makes up the lentiform nucleus?
putamen and the globus pallidus
what is the role of Subthalamic Nuclei ?
produces the excitatory neurotransmitter, Glutamate.
what is the role of Substantia Nigra?
produces the neurotransmitter dopamine
How is the cerebellum anatomically split?
The cerebellum consists of two hemispheres which are connected by the vermis, a narrow midline area.
what are the anatomical lobes of the cerebellum? what divides them?
the anterior lobe, the posterior lobe and the flocculonodular lobe.
These lobes are divided by two fissures – the primary fissure and posterolateral fissure.
what are the anatomical zones of the cerebellum?
intermediate zones on either side of the vermis
lateral zones on either side of intermediate zones
descending motor pathways can be spilt into lateral and ventromedial pathways. what comes under these 2 types of pathways and what is their role?
Lateral pathways: corticospinal and rubrospinal tract – control of voluntary movement and distal muscle groups
Ventromedial pathways: tectospinal, vestibulospinal, olivospinal, reticulospinal (pontine + medullary) – mainly control proximal and axial (trunk) muscles and maintain posture
where does the corticospinal tract begin and where does it receive input from?
begins in the cerebral cortex receives input from: • Primary motor cortex • Premotor cortex (PMA) • Supplementary motor area (SMA) • nerves from somatosensory area
describe the path of the corticospinal tract after leaving the cerebral cortex. Describe the decussation of nerve fibres
the neurons descend through the internal capsule (a white matter pathway, located between the thalamus and the basal ganglia). The neurons then pass through the crus cerebri of the midbrain, pons and into the medulla.
In the caudal part of the medulla, the tract divides into 2:
- lateral corticospinal tract (85%) decussate at level of medulla and then descend into the spinal cord, terminating in the ventral horn (at all segmental levels). From the ventral horn, the lower motor neurones go on to supply the muscles of the body.
- The anterior corticospinal tract (15%) remains ipsilateral, descending into the spinal cord. They then decussate and terminate in the ventral horn of the cervical and upper thoracic segmental levels.
describe the corticobulbar pathway (arises from? input from? passage?)
arises from lateral aspect of the primary motor cortex.
They receive the same inputs as the corticospinal tracts.
The fibres converge and pass through the internal capsule to the brainstem.
The neurones terminate on the motor nuclei of 9 pairs of cranial nerves. Here, they synapse with lower motor neurones, which carry the motor signals to the muscles of the face and neck.
Describe dopamine synthesis
The amino acid tyrosine (aromatic aa derived from diet) is converted to Leva-dopa by tyrosine hydroxylase. It is then decarboxylated to dopamine by dopa decarboxylase in the brain.
what prevents dopamine from being converted to noradrenaline?
Dopaminergic neurons lack dopamine β-hydroxylase
what are the 2 main dopamine rich areas in the brain?
- Substantia nigra
* Ventral tegmental area
name 4 dopamine pathways
Nigrostriatal pathway
Mesolimbic pathway
Mesocortical pathway
Tuberoinfundibular/hypophyseal pathway
