The Cerebrum Flashcards
(22 cards)
What are the 4 constituent parts of the cerebrum?
The telencephalon (cerebral hemispheres), the basal gangila, the olfactory bulb and limbic system
What is the name of the structure that divides the 2 hemispheres? What structure joins them together?
The longitudinal fissure.
The corpus collosum - white matter commisural fibres.
What is the cerebral cortex?
The outer 1.5-5mm of the cerebrum that is convoluted to increase the surface area. It is located superiorly to the brainstem and cerebellum.
What is the difference between a gyrus and a sulcus?
Gyrus is the ‘hill’ or the ridge
Sulcus is the ‘valley’ or groove
Where is the central sulcus?
Seperates the frontal and parietal lobes.
Where is the lateral sulcus?
Seperates the frontal, parietal and temporal lobes.
Where is the posterior sulcus?
Seperates the parietal and occipital lobes.
What are commisural fibres?
They connect the 2 hemispheres together e.g. the corpus collosum.
What are association fibres?
They connect areas within the same hemispheres.
What are projection fibres?
They connect the brain to different levels of the spinal cord e.g. the CST.
What is the internal capsule?
A subcortical structure containing white matter projection fibres
What is the amydala?
A almond shaped structures deep in the temporal lobe that process memory, decisions and emotional reactions.
What is the hippocampus?
A sea-horse shaped structure in the temporal lobe that processes memory and spatial navigation.
Name the motor planning areas
Pre-mc
Supplementary mc
pre-frontal area
What is the role of the supplementary motor cortex? Where is it located?
Initiates and plans movements that are bimanual in a sequence/order.
Located superiorly to the pre-mc
What is the role of the pre motor cortex? Where is it located?
Controls trunk/girdle muscles
Pre-positions the body for movement.
Located inferior to the supplementary mc.
What is the role of the pre - frontal area? Where is it located?
Instigates the decision to move. Located anterior of the brain.
What is the role of the primary motor cortex? Where is it located?
Responsible for contralateral voluntary movement of skeletal muscle fibres.
What is the main pathway that relays motor information? What other structures does it work with for movement?
The corticospinal tract.
- This works with the basal ganglia to plan/initiate movement
- It also works with the cerebellum to
Describe the stages of this tract.
control/coordinate movement.
The command to move comes from the primary motor cortex in the pre-central gyrus of the frontal lobe. This command occurs after communication with the other areas of the motor cortex such as the supplementary cortex via association fibres.
The impulse travels from the primary motor cortex down via the corona radiate as the decussation of pyramids, passing through the internal capsule and the brain stem to reach the medulla. Here, 90% of fibres cross to the other side of the medulla as internal arcuate fibres. The remaining 10% do not cross at the medulla. The 90% travel down the lateral corticospinal tract to the anterior horn cell as their target cell in the ventral horn of the spinal cord. Before this occurs, they summate at an inter neurone. The 10% of fibres descend from the medulla via the anterior corticospinal tract and reach the level of the spinal cord and cross, targeting the anterior horn cell. Here they synapse.
The alpha motor neurone conveys this impulse to the skeletal muscle fibres (namely the extrafusal fibres of the muscle spindle) via a neuromuscular junction = movement.
Describe the cortico-bulbar tract
This relays information from non-occulomotor cranial nerves from the brainstem to the cerebral cortex.
Describe the spinocerebellar tract
This conveys unconscious proprioception and is unilateral. It targets the spinocerebellum.
