Session 4 - CNS Basics Flashcards
What are the basic components of the CNS?
- Cerebral Hemispheres
- Brainstem and cerebellum
- Spinal Cord
What are the main components of the Peripheral Nervous System (PNS)?
- Dorsal and ventral roots
- Spinal Nerves
- Peripheral Nerves
Describe the dorsal and ventral surfaces of the brain.
Inferior brain is ventral (due to right angle curve)
Superior brain is dorsal
What is the main immune cell of the brain?
Microglia - make up 10-15% of cells of brain.
Macrophages for the CNS.
Which cells are responsible for myelination in the CNS and PNS?
CNS - Oligodendrocyte - cell which gives of arms which myelinate many neurones, insulating the CNS.
PNS - Schwann Cells
Which nervous system cells can regenerate?
CNS - cannot regenerate
PNS - can regenerate to en extent.
What is the difference between tumours in the CNS and PNS?
CNS- tumours can be benign OR malignant.
PNS- tumours tend to be benign.
What are the parts of the brainstem?
1) Midbrain = Eye movements and reflex responses.
2) Pons = Feeding, Sleep
3) Medulla Oblongata = CVS and Resp centres, contains major motor pathway (Medullary Pyramids)
Where do the trigeminal nerves originate?
The lateral surface of the Pons.
What is decussation?
When the motor fibres from the brain cross over in the medulla oblongata. (medullary pyramids)
What is a sulcus, and a gyrus?
Sulcus - A groove or furrow in the brain (seperated by adjacent gyrus).
Gyrus - A ridge or fold in the brain.
What is a brain fissure?
A large ‘crack’ or ‘split’ between adjacent large areas of the brain.
Name the lobes/ parts of the brain, and their function.
Frontal Lobe
-Higher cognition, Motor function, speech
Parietal Lobe
-Sensation, spatial awareness
Temporal Lobe
-Memory, smell, hearing
Cerebellum
-Coordination and motor learning.
Why is the optic chiasm clinically significant, where is it located?
Inferior aspect of the brain.
Located very close to pituitary, pituitary tumours can cause visual disturbance. (compression)
Where is the uncus located? What is its clinical importance?
Inferior brain.
If there is increased intracranial pressure, the uncus can herniate into the brainstem.
(Fixed dilated pupil on contralateral side - no constriction with torch)
What is the location of the corpus callosum?
Fibres connecting the two cerebral hemispheres.
Describe the clinical importance of the corpus callosum. In which condition?
Epilepsy in the brain (misfiring of neurons)
If sever can travel between hemispheres of the brain via the corpus callosum.
Clinically can be cut/disconnected, to reduce severity and travel to other side.
Where are the thalamus and hypothalamus?
Thalamus Inferior to Fornix (inferor to corpus callosum)
Thalamus is superio-posterior to hypothalamus.
What are the functions of the thalamus and hypothalamus?
Thalamus = Sensory relay station projecing to sensory cortex. Hypothalamus = Essential centre for homeostasis.
How would an embolus from an internal carotid atheroma cause temporary loss of vision?
Internal carotid gives the ophthalmic branch which supplies the ORBIT and RETINA.
TIA - transient ischaemic attack - ischaemia to retina.
Temporary blindness (monocular blindess)
What is the location of the primary motor cortex, and the primary somatosensory cortex?
Primary motor cortex - anterior to the central sulcus.
Primary somatosensory cortex - posterior to central sulcus.
A man has motor weakness and paraesthesia involving the left half of the face, and left arm.
A stroke is suspected. Which part of the brain would the stroke have occured in?
RIGHT side.
Frontal and Parietal Lobe.
(around the primary motor and somatosensory cortexes)
(Look at homunculus)
A scan of a patient shows a right cerebellar tumour. What would be some clinical signs she potentially presented with?
Impairment of RIGHT sided motor control, coordination or fine tune of movements.
(Remember cerebellar control is IPSILATERAL)
