Cerebral hemispheres - White matter (2nd half) Flashcards
What are the 3 types of white matter found inside the cerebrum?
Commissural fibres:
- These fibres connect corresponding areas of the two hemispheres
- Example - Corpus callosum
Association fibres:
- Connect one part of the cortex to another on the same side
- Can be short or long fibres
- These are the ones that connect primary areas to association areas funnily enough
Projection fibres:
- These are the ones that travel from the cortex to places outside of the cerebrum (or vice versa)
- Eg sensory fibres coming from the fingers to the PSC
- Pass through the corona radiata & the internal capsule
Identify the different types of fibres in the diagram
What is 3D cerebral tractography?
3D modelling technique that maps functional white matter tracts in the brain using MRI
Done by yer boi Alan Denison
Identify the labelled structures
Tell me about the one that is coloured in red (that isnt labelled)
Internal capsule (coloured in red):
- Narrow area between the thalamus and caudate nucleus medially and the lentiform nucleus laterally
- Made up of Projection fibres - passing to and from the cerebral cortex (so motor & sensory)
- derives blood supply from the middle cerebral artery and is frequently affected in a stroke
Literally everything passing to/from the cerebral cortex must go through this
What are basal ganglia?
Group of Subcortical Nuclei situated at the base of the forebrain and top of the midbrain
They are associated with a number of functions but their main role is to help regulate the initiation and termination of movements
What are the different basal ganglia?
- Caudate nucleus
- Putamen
- Globus pallidus
- Substantia Nigra (watch how you spell this one)
- Subthalamic nuclei
Putamen and Globus pallidus together form the Lentiform Nucleus (looks like a lens)
Identify the different structures on the diagram
Where does the caudate nucleus lie?
Starts as a large head medial to the internal capsule, a body and a slender curving tail which follows the curve of the lateral ventricle.
Basically follows it but a bit more laterally
Where does the lentiform nucleus lie?
Just lateral to the internal capsule
Remember the Putamen is the shell - so lies laterally
the Globus pallidus is on the medial corner of the lentiform nucleus
The caudate nucleus and putamen are described as ‘input regions’
What does this mean?
They receive input from the motor cortex, premotor cortex, and from the thalamus
The CN & putamen are in turn connected to the output regions - the globus pallidus and the substantia nigra
What is the role of the Globus pallidus as an output region?
The globus pallidus projects primarily to the thalamus (which in turn sends fibres to the motor area of cortex)
Complete the schematic of the basal ganglia communications
Why has the input/output role of the basal ganglia led them to be called the Extra-pyramidal
The system has lots of connections to the motor pathway but is not part of the pyramidal tract/motor tract
Hence ‘extra’ pyramidal
Identify the stuff (last one i promise)
