Topography Of Central Nervous System Flashcards
Basic components of central nervous system
Cerebral hemispheres
Brainstem + cerebellum
Spinal cord
What is grey matter composed of?
Cell bodies
Dendrites
Highly vascular
(Some axons)
What is white matter composed of?
Axons
+ supporting cells
Why is white matter white?
Presence of fatty myelin
Define nucleus in terms of CNS
A collection of functionally related cell bodies
Grey matter
Define cortex in terms of CNS
Folded sheet of cell bodies found on surface of brain structure
Grey matter
Describe fibre in terms of CNS
A term relating to an axon in association with its supporting cells e.g. oligodendrocytes
White matter
Types of fibres in the CNS
What do they connect?
- Association fibres: cortical regions with same hemisphere
- Commissural fibres: left and right hemispheres
- Projection fibres: cerebral hemispheres with brainstem
What are grey and white matter termed in the peripheral nervous system
grey - ganglion
white - nerve
How many segments is the spinal cord made up of?
~31
Describe the composition of matter in the spinal cord
Central grey matter
Outer shell of white matter
What do association fibres connect?
Cortical regions within same hemisphere
What do commissural fibres connect?
Left and right hemispheres
What do projection fibres connect?
Cerebral hemispheres with brainstem
What do these suggest?
- sensory deficit in dermatomal pattern
- sensory deficit across multiple segments
- sensory deficiency in homuncular pattern
- dermatomal pattern: lesion at level of doral root or spinal nerve
- multiple segments: cord lesion
- homuncular pattern: lesion above thalamus
What does a sensory deficit in dermatomal patter suggest?
Lesion at level of dorsal roots or spinal nerves
What does a sensory deficiency across multiple segments suggest?
Cord lesion
What does a sensory deficit in a homuncular pattern suggest?
Lesion above thalamus
Define funiculus
- A segment of white matter containing multiple distinct tracts
- Impulses travel in multiple directions
Define tract
- Anatomically + functionally defined white matter pathway connecting two distinct regions of grey matter
- Impulses travel in one direction