CNS anatomy Flashcards
what are the two parts of the CNS
visceral and somatic
what is the somatic part
recieving and responding to information from the external environment
what is the visceral part
innervation of organs in the body and other components, more connected with the internal
what does the CNS do
controls and coordinates most functions of the body and mind
what does the CNS include
spinal cord and brain
role of CSF
supports and protects the brain and spinal cord by maintaining uniform pressure
shock absorber between brain and skull
keeps brain and SC moist
exchange of nutrients and waste between CSF and interstitial fluid
acts as a cushion for the brain, making it weightless
keeps the brain in place
regulation of breathing, bathes the medulla where the central respiratory chemoreceptors are found
what does CSF contain
glucose [gives it a slight yellow colour], lactic acid and proteins
where does CSF exit
through the meninges into the venous supply
what happens to CSF if brain is enlarged
fluid levels decrease
what happens if the brain volume decreases
CSF levels increase
what allows for the secretion of CSF into each ventricle
choroid plexus [highly vascularised]
what cells is the CSF surrounded by
ependymal cells
how does CSF pass back into the blood
by the arachnoid villi, composed of arachnoid matter which project into the venous sinuses
what does the movement of CSF depend on
the pressure at each side of the villi walls, transferring it from the arachnoid space to the venous sinuses
what happens to the CSF movement if CSF pressure is higher than venous pressure
CSF pushed into the blood
what happens if the venous pressure is greater
the arachnoid villi collapse preventing passage of blood constituents into CSF
formanen of monro
sits behind part of the BS
from 4th to SC
reabsorbed back into circulation via meninges
what is the blood supply
circulus arteriosus + arteries maintain constant supply of oxygen and glucose to the brain, when the head moves, the contributing artery becomes narrowed
autoregulation of cerebral arteriolar diameter maintains constant blood flow to the brain compensating for fluctuations, protecting the brain
venous blood drains into the dural venous sinuses -> IJ vein
what should the systemic BP be
65-140mmHg
what is the arterial blood supply
carotid feeds through the neck
vertebral + internal carotid = connected in the inter cranial space = cerebral arterial circle of willis
two vertebral arteries enter the cranial cavity through the foramen magnum forming the basillar artery
what causes a stroke
blockage of blood to the brain
what causes a haemorrhage
over blood supply
what causes vascular dementia
diameter constriction, less blood to brain causes confusion
what are the four ventricles
left
right
3rd
4th
where are the lateral ventricles
in the central hemisphere on each side of the median plane below the corpus callosum
separated by a narrow septum and lined with ciliated epithelium
what do the lateral ventricles communicate with
the 3rd ventricle via the inter-ventricular foramen
where is the 3rd ventricle found
below the lateral ventricles, between the 2 parts of the thalamus
what does the 3rd ventricle communicate with
the 4th by the canal aqueduct, it recieves CSF fluid via the cerebral aqueduct
where is the 4th ventricle
sits below and behind the 3rd between the cerebellum and the pons
slightly alkaline and has a specific gravity of 1.005
consists of water, salts, glucose, plasma proteins, leukocytes, creatinine, urea
what is hydrocephallis
blocked ventricle, excess CSF which builds up, failing to reabsorb
causes intracranial pressure and can link to meninge issues
how do CSF leaks present
headaches, relief whilst laying down
lack of CSF can cause collapse, as brain becomes heavy
CSF leak SE
nausea, headaches, confusion, vomiting, clear fluid from ear and injury site
what is the BBB
it is a semipermeable barrier which allows small molecules in via diffusion as well as selective + AT of various nutrients and ions and anions and macromolecules
protects the brain tissue from pathogens + toxic substances
what cant pass through the BBB
chemo BUT TEMZ
however a reservoir can be put in so that small doses of chemo can be given
what can pass through the BBB
oxygen, carbon dioxide, glucose, lipid soluble
inorganic ions, AA pass slowly or not at all
what are the two types of cell of the brain
neurons and glial
what is a feature about neurones
THEY DONT DIVIDE
ONCE THEY DIE THEY CANT BE REPLACED
what do sensory neurons do
detect stimuli from external
what do motor neurones do
carry impulses from brain to muscles
what do interneurones do
connect other nerve cells and help relay messages between the brain and other body cells. They allow impulses from sensory neurons -> brain -> motor
what structures are grey matter
brain, BS, cerebellum, SC
what is GM
six layers of neurons, axon terminals and dendrites
what does grey matter do
send nerve signals which govern motor activity to nervous system
what does white matter do
myelinated, conductor of nerve signals which process them
conducts, sends and processes signals and responds
there is more white matter so signals can respond after they’ve been replaced
what are the different glial cells
ependymal
astrocytes
oliogodendrocyte
microglia
what is the role of the glial cells
support the neurones and protect them
regulate chemical environment
role repair in trauma
what is the role of astrocytes
clean up dead neurons
fine branching processes lie in a mucopolyssacharide ground substance
biochemical control which line the BBB
tells the transmitters what to do after the message has been delivered
contributes to homeostasis
structural support of CNS
linked with parkinsons
what happens when the astrocytes get damaged
the processes form a mesh as they multiply, which inhibits regrowth of damaged CNS neurones
what are ependymal cells
hair like projections which move CSF fluid through fluid filled cavities, which form the lining of the ventricles and the central canal of the SC
what would happen if there was no ependymal cells
build up of fluid would occur
what do specialised ependymal cells form
choroid plexuses of the ventricles and secrete CSF
what are oligodendrocytes
cluster of nerve cells bodies in grey matter which are found adjacent to and along the mylelinated nerve fibres
what do the oligodendrocytes form
the myelin sheath around the neurons, faster transmission of information sending, also contains multiple branches which speeds up transmission also.
it protects the neurons, and the gap allows for conduction and impulse of messages, which multiply around degenerating neurones
how are oligodendrocytes destroyed
in demyelinating diseases
what are microglia
cells derived from monocytes which migrate from the blood to the nervous system. Which remove damaged and infected cells maintaining CSF is a healthy state
static cells are found dispersed throughout the brain
what are microglia part of
the mononulear phagocyte system
what are the types of meninges
cranial
spinal
what do meninges do
they stop the brain/cord from touching bone, contains a blood supply, produces CSF
where are meninges
lie in between the skull and the brain, and between the vertebral foramina and spinal cord
brain and SC are completely surrounded by three layers of tissue
what are the 3 layers of tissue
[outwards - in]
dura mater
arachnoid mater
pia mater
what is found between the dura mater and the arachnoid mater
subdural space - serous fluid
what is found between the arachnoid mater and pia mater
subarachnoid space = contains CSF
these 3 layers continue in the…..
spinal canal, containing the epidural space
what is dura mater composed of
two layers of dense fibrous tissue
outer periosteal layer lines the inner surface of the skull, bones and inner meningeal layer, provides a protective covering.
what does the inner layer of dura mater do
sweep inwards following the brain contours, forming membranous extensions that particularly divides the cranial cavity
what is the flax cerebri
separates the 2 central hemispheres, penetrates the depth of the corpus callosum
what is the falx cerebelli
separates the 2 cerebellar hemispheres
what is the tentorium cerebelli
separates the cerebellum and the cerebrum
what is the venous blood supply of the dura mater
venous sinuses are found in between the two layers, superior sagittak sinus is formed by the falx cerebri and tentorium.
cerebelli forms straight and transverse sinuses, allows blood to leave and CSF to re-enter the venous supply
what is the arachnoid matter made from
fibrous tissue
arachnoid mater
passes over the convolutions of the brain and accompanies the inner layer of the dura mater in the formation of the falx cerebri, tentorium cerebelli and falx cerebelli
where does the arachnoid mater end
at S2, as it merges with the dura mater
what is pia mater made from
connective tissue with tiny blood vessels which adhere to the brain covering the brain convolutions and dipping into each fissure
what does the pia continue as at the end of the cord
filium terminale
what does the fused pia mater and dura mater become
coccyx periostenium
what is the role of the pia mater
act as a physical barrier, separating the neural tissue
what is the extradural space
space between the dura mater and the bone which have air spaces to reduce trauma
what are the two spaces where CSF flows
arachnoid space and subarachnoid
where does the arachnoid space continue to
S2
what is the spinal cord protected by
vertebrae, meninges, CSFwh
where do the nerves fan out to become causa equina
L1/L2
where does the SC extend from
foramen magnum - L1/L2
is ventral front or back
front
is dorsal front or back
back
how many pair of nerves are there
31
what holds the spine in place
erectus spinus
how many C vertebrae
7
how many L spine is there
5
how many T spine is there
12
how many S spine is there
5
what spine is in the upper limbs
C5-T1
what spine is in the lower limbs
L1-S3
what is the coronal suture
fusion of the frontal bone and the two parietal
what is the sagittal suture
fusion of the two parietal
what is the lamboid suture
fusion of the occipital bones to the parietal
what are sutures
keep the skull sections fused together
what does the falx cerebri divide into
left and right cranium
what does the falx cerebri determine
the site of the sutures
what does the falx cerebri attach to
part of the ethmoid bone (crista gali) which extends to the occipital protuberance
what is meningitis
inflammation of the meninges [amputation, seizures, death]
can be cancer induced
mengioma is it malignant
no it is benign
haematoma
vascular damage due to trauma, extradural space becomes fluid/blood filled
what are the spinal nerves attached to
posterior and anterior roots
posterior roots
carry information TO CNS (contains sensory neuron processes)
anterior roots
carry information FROM CNS (contains motor fibres)
what do dorsal problems cause
issues interpreting sensory info
what do ventral issues cause
body’s ability to receive motor information, paralysis, tingling, muscle weakness
what is heavy leg syndrome linked with
ventral root
what is spina bifeda
inproper formation of the spine
weakness in legs, bowel/urine incontinence, cant feel hot or cold
birth defect [nerves outside the body]
what does motor neurone disease cause
muscle weakness, slurred speech
unpreventable
where is the cerebrum located
anterior, middle cranial fossa, divided by a deep cleft, longitudinal cerebral fissure into. right and left hemisphere each containing a lateral ventricle
what is the corpus callosum
the connection of two hemispheres by white matter
what does the cerebrum do
cross and fine motor skills
hand eye coordination
balance
what is bells palsy
one sided face weakness
what is the cerebral cortex composed of
nerve cell bodies - superificial
nerve fibres - deep layers
exposed areas = gyri (convolutions) are separated by sulci (fissures) increasing the SA
what does the motor areas of the cerebral cortex do
initate and control skeletal muscle movement
what does the sensory areas of the CC do
receive and decode sensory impulses, enabling pain perception, temp, touch, light, sight, hearing, taste and smell
what do the associated areas of the cerebral cortex do
integration and processing of mental functions [intelligence, memory, reasoning, judgement and emotions]
what functions are associated with anterior of the central sulcus
motor
what functions are associated with posterior of the central sulcus
sensory
what are the different lobes
temporal
occipital
parietal
frontal
what marks the lobe boundaries
deep sulci
what are the different sulci
central
lateral
parieto-occipital sulci
what increases the SA of the brain
gyri and sulci
what does the parietal lobe contribute to
object classification
knowledge of numbers
visuo-spacial processing
spelling
perception
what does the frontal lobe contribute to
thinking
processing information
planning
behaviour control
problem solving
emotions
decision making
motor speech [brocos area = just above the lateral sulcus, controls the muscle movements for speech]
what does the temporal lobe contribute to
memory
speech
vision
hearing sensitivity to sound and how nerves process it
facial recognition
understanding language
what does the occipital lobe contribute to
vision
colour identification
visual processing
what does the corpus callosum act as
a communicator for the left and right side of the brain
[bundle of nerves along the longitudinal fissure]
why is good oxygen supply needed
optimal processing
what does the internal capsule connect to
cerebral cortex and other structures ie thalamus and brainstem
what do the nerve fibres in the internal capsule form
pyramidal tracts which cross at the medulla oblongata (to the skeletal muscles), ones which dont pass through have connections to parts of the brain: basal ganglia, thalamus and cerebellum
what is the role of basal ganglia
initiation and fine motor control of complex movement, learned coordinated activities
what happens if motor control is inadequate
jerky movements, clumsy and uncoordinated
what is the diencephalon
connection of the cerebrum to the BS
what is the thalamus
relay station for sensory impulses, role in memory, sleep wake signals
what is the olfactory bulb responsible for
smell
what is the amygdala
fight or flight
produces adrenaline
what is the pineal gland responsible for
sleep/wake cycle
sensitive to steroids
where is the pineal gland located
behind the corpus callosum, secretes melatonin
what is the roles of the hypothalamus
heart rate
BP
body temp
glandular secretions of stomach and intestines
sleep cycles
secretions of substances which influence pituitary gland to release hormones
appetite and body weight
fluid and electrolyte balance
what is the hippocampus responsible for
recalling info
memory station: converts short term to long term
alzheimers
where is hippocampus found
temporal lobe
what is the brainstem responsible for
communication between brain + SC
control centre
contains 10/12 nerves [- optic and olfactory]
what is the midbrain responsible for
hearing
vision
temp regulation
eye movement
motor control
sleep/wake cycle
alertness
what is the pons responsible for
connects L+R hemisphere
sleep
respiration
swallowing
bladder control
body movements
what is the medulla responsible for
respiratory
digestive system
cardio system
regulation autonomic involuntary functions: breathing, heart rate, BP
vomiting
describe the location of the brain stem etc from top to bottom
thalamus
midbrain
pons
medulla
SC
[midbrain to SC = brain stem]
what is the basal ganglia responsible for
fine motor skills [involuntary]
receives impulses from the cerebrum, processed and adjusted which are sent to the thalamus and info is relayed back to the GM of the cerebrum before signals are sent to the spine
where is the basal ganglia found
deep within WM
where is the taste area of the limbic system
above the lateral sulcus, in the deep layers of the somatosensory area
sensory receptors in taste buds are received and interpreted
what is the limbic system
the sensory areas of the cerebral cortex
where is the auditory area of the limbic system
below the lateral sulcus within the temporal lobe
what does the auditory area do
nerve cells receive and interpret impulses transmitted from the inner ear by the cochlear of the vestibulocochlea nerves
where is the somatosensory area
behind the central sulcus
what does the somatosensory area do
pain sensation, temp, pressure, touch, awareness of muscular movement and joint position
right hemisphere receives impulses from the left side of the body and vice versa
what is the size of the cortical areas proportional to
the extent of the sensory innervation
where is the olfactory area in the limbic system found
deep within the temporal lobe
what do the olfactory nerves do in the LS
receive and interpret impulses
what are the areas of the limbic system
auditory
sensory
taste
somatosensory
olfactory
[vestibular relates to touch, NOT AN AREA THOUGH]
