Central Nervous System Flashcards
How is the nervous system divided?
anatomically and functionally, into:
CNS
PNS
What does the CNS consist of?
brain
spinal cord
What does the PNS consist of?
cranial nerves (from brain) spinal nerves (from spinal cord)
How does the CNS develop?
from a hollow tube, where:
- one end becomes enlarged (rostral)
- one end is non-enlarged (caudal/tail)
What happens to the rostral end of the developing hollow tube that forms the CNS?
ultimately becomes the brain
What happens to the caudal/tail end of the developing hollow tube that forms the CNS?
remains as spinal cord
What are the 3 compartments that the rostral end of the hollow tube divide into?
forebrain
midbrain
hindbrain
What does the forebrain. subdivide into?
telencephalon and diencephalon
What does the midbrain divide into?
remains as mesencephalon
What does the hindbrain become?
metencephalon (pons) and myelencephalon (medulla)
What is the cerebellum?
outgrowth from hindbrain that is involved in control of movement
Telencephalon
What are the 2 structures involved?
cerebrum
basal ganglia
Telencephalon
What is the cerebrum composed of?
2 cerebral hemispheres
Telencephalon
What is the cerebrum the site of
site of ‘highest’ level of neuronal processing responsible for motor activity, sensory perception, consciousness, etc.
Telencephalon
What is the cerebral cortex?
outer layer of cerebrum composed of grey matter
Telencephalon
What is the grey matter of the cerebrum?
neuronal cell bodies, dendrites, synapses
Telencephalon
What is the white matter of the cerebrum?
myelinated axons arranged in discrete bundles (tracts), located below cortex
Telencephalon
How much volume of the brain does the cerebrum make up?
~85% total brain volume
- after 11 weeks, expanding cerebral hemispheres have overgrown diencephalon
Telencephalon
What do basal ganglia do?
involved in movement control
Diencephalon
What are the 2 structures that arise?
thalamus
hypothalamus
Diencephalon
What does the thalamus do?
important relay station for processing information going to cerebrum
Diencephalon
What does the hypothalamus do?
fundamental role in regulation of ‘automatic’ bodily functions
Brainstem
What are the 3 structures that make up the brainstem?
midbrain
pons
medulla
Brainstem
What are 2 other components in the brainstem?
white matter
nuclei
Brainstem
What does white matter do?
carry information to or from cortex
Brainstem
Where is white matter found?
all levels of brainstem contain tracts of white matter
Brainstem
What are nuclei?
groups of cell bodies
Brainstem
What do nuclei do?
responsible for function of cranial nerves
What is reticular formation?
set of interconnected nuclei located throughout brainstem, forming central core of brainstem
What are the 3 main functions of the reticular formation?
ascending: responsible for generation and maintenance of arousal and consciousness
descending: responsible for generation and maintenance of muscle tone
respiratory and cardiovascular centres: of fundamental importance, located in medulla
What are ventricles?
series of chambers developed from a cavity of the primitive tube
What are the 4 ventricles?
lateral ventricles (2 – left and right)
3rd ventricle
4th ventricle
Where are the lateral ventricles (2)?
left and right cerebral hemispheres
Where is the 3rd ventricle?
(midline) located in diencephalon, between thalami
Where is the 4th ventricle?
located between dorsal surface of pons and overlying cerebellum
What is the cerebral aqueduct?
connects 3rd and 4th ventricles
What does CSF fill?
ventricles
What is CSF produced by?
produced continuously by choroid plexus (specialized tissue)
What happens to CSF if there’s an obstruction somewhere?
fluid will accumulate upstream to the obstruction – results in hydrocephalus
Where does CSF travel?
- CSF leaves ventricular system via apertures between cerebellum and medulla
- fluid fills space surrounding entire CNS (brain and spinal cord) – ~90% of CSF volume is in this space
What system is CSF apart of?
ventricular system
What are the functions of CSF?
- buoyant effect – protects against tendency of various forces (including gravity) to distort brain
- excretion of waste (metabolic by-products from neurons and glia)
- transport of hormones
What are the 3 membranes that cover the outer surface of CNS?
pia mater
arachnoid membrane
dura mater
What is the pia mater?
inner membrane layer – follows indentations of surface
What is the arachnoid membrane?
middle membrane layer – fits ‘loosely’ over surface
What space does the arachnoid membrane create?
subarachnoid space – space between pia mater and arachnoid membrane
Describe CSF in the arachnoid membrane.
- CSF is located beneath
- arachnoid membrane has rich blood supply (veins) – CSF is reabsorbed back into veins at this site
What is the dura mater?
outer membrane layer– very thick and tough, with a protective function
