Flashcards in 1.1 Introduction to NS and Topography Deck (64):
What makes up the CNS? And what do they develop from?
Brain and Spinal Cord
Develop from the neural tube
What makes up the PNS?
Dorsal and ventral roots
What makes up the caudal equina?
Dorsal and ventral roots
Collections of cell bodies in PNS
What is grey matter comprised of?
Cell bodies and dendrites
How is grey matter adapted for its computational role?
It is highly vascularised to provide for its high metabolic demands
Why is grey matter grey?
Not much fat
What is white matter composed of?
Axons (with their supporting cells)
Why is white matter white?
Presence of fatty myelin
What is the PNS equivalent of grey matter?
What is the PNS equivalent of white matter?
How many segments is the SC composed of?
Describe the structure of the cord
Central core of grey matter and outer shell of white matter
Where does the SC extend from and to?
Foramen magnum -> L1
Is white matter homogenous?
It has different regions with different functions
A segment of white matter containing multiple distinct tracts
Impulse travel in multiple directions
(Large block of white matter with axons going up and down in SC)
Dorsal, lateral, ventral
An anatomically and functionally defined white matter pathway connecting two distinct regions of grey matter
Impulses travel in one direction
A subdivision of a tract supplying a distinct region of the body
Give an example of fasciculi
Gracilis (lower body) and cuneatus (upper body) in the dorsal column tract
How is grey matter organised?
Into cell columns
What is a nucleus formed from?
The motor neurones supplying a given muscle arise from multiple segments and forma distinct population of neurones in the CNS
Define nucleus (grey matter)
A collection of functionally related cell bodies
Define cortex (grey matter)
A folded sheet of cell bodies found on the surface of a brain structure
How thick is the cortex usually?
Define fibre (white matter)
A term relating to an axon in association with its supporting cells
(also called an axon)
What do association fibres do?
Connect cortical regions within the same hemisphere
What do commissural fibres do?
Connect left and right hemispheres or cord halves
What do projection fibres do?
Connect the cerebral hemispheres with the cord/brainstem and vice versa
What is another name for the midbrain?
What is another name for the pons?
What is another name for the medulla oblongata?
What are the roles of the midbrain?
Reflex responses to sound and vision
What are the roles of the pons?
Feeding (and suckling)
What are the roles of the medulla?
Cardiovascular and respiratory centres
Contains a major motor pathway (medullary pyramids)
How can the central sulcus be identified?
Sits in the coronal plane
Goes from the temporal line laterally to the midline unimpeded
What does the pre-central gyrus contain?
The primary motor cortex
What does the post-central gyrus contain?
Primary sensory cortex
What does the lateral fissure do? and what is its other name?
Separates the temporal from frontal/parietal lobes
What does the parieto-occipital sulcus do?
Separates parietal from occipital lobe
What surrounds the calcarine sulcus?
Primary visual cortex
What is the optic chasm?
A site where fibres in the visual system cross over
What is the uncus?
Part of the temporal lobe that can herniate, compressing the midbrain
Has an important olfactory role
What is located in the medullary pyramids?
Descending motor fibres
What is the parahippocampal gyrus?
Key cortical region for memory encoding
What does the corpus callosum contain?
Fibres connecting the two cerebral hemispheres
What is the thalamus?
Sensory relay station projecting to sensory cortex
What is the cingulate gyrus?
Cortical area important for emotion and memory
Part of the limbic system for emotional processing
What is the hypothalamus?
Essential centre for homeostasis
What is the fornix?
Major output pathway from the hippocampus
What is the tectum?
Dorsal part of the midbrain involved in involuntary responses to auditory and visual stimuli
What is the cerebellar tonsil?
Part of the cerebellum that can herniate and compress the medulla
What are cavities in the brain called and why do they develop?
Because the brain is hollow as it developed from a hollow tube (neural tube)
What do the ventricles contain?
Choroid plexus (highly vascularised) which make 600-700ml in total of CSF a day
What two groups of functions does CSF have?
Metabolic and mechanical
Describe the movement of CSF
CSF circulates through the ventricular system and subarachnoid space before being reabsorbed
Where is CSF reabsorbed?
At the arachnoid granulations
Where do the two lateral ventricles join?
At the inter ventricular foramen
Why is the third ventricle flattened?
It is sandwiched between the two halves of the thalamus
What shape is the fourth ventricle?
What is the 4th ventricle continuous caudally with?
Central canal of SC
Why does not much CSF go into the cord?
Because the central canal is very narrow
How does CSF get to the subarachnoid space?
2x lateral apertures
What happens to CSF once it leaves the subarachnoid space?
Drains into the venous blood through granulations in the superior saggital sinus