CNS Flashcards
What is the CNS composed of?
brain and spinal cord
What are 4 parts of the CNS?
Cerebrum, cerebellum, brainstem and spinal cord
what are the three parts the brain can be split up into?
Forebrain, midbrain, hindbrain
what is the forebrain composed of?
diencephalon, cerebral hemispheres
what is the hindbrain composed of?
pons,medulla,cerebellum
what is the diencephalon composed of ?
thalamus and hypothalamus
what is the brainstem composed of?
midbrain, pons, medulla
briefly describe what the hypothalamus does?
it has lots of nuclei which secrete neurotransmitters into the blood supply that supplies the pituitary gland and it causes it to secrete hormones.
what are the four lobes?
parietal, frontal, occipital, temporal
what is the function of each of the four lobes?
frontal- motor function, cognitive function(planning memory, executive function-mulitasking),language
parietal-sensation, spatial orientation and self-perception
temporal-auditory
occipital- vision
what is the name of the sulcus that separate the frontal and parietal lobes?
Central sulcus
where is the pre and post central gyrus located and what primary cortices do they each contain?
pre-central gyrus in frontal lobe and has the primary motor cortex.
post-central gyrus is in the parietal lobe and has the primary sensory cortex
what is the name of the component that separates the frontal and parietal lobe from the temporal lobe?
lateral fissure
what is the name of the component that separates the parietal lobe from the occipital lobe?
parieto-occipital sulcus/fissure
what does the limbic lobe include?
hippocampus, cingulate gyrus, mammillary body, amygdala
what is the limbic lobe concerned with?
learning, memory , emotion, motivation and reward
where is the insular cortex (lobe) located?
lies deep within the lateral fissure
what is the insular cortex (lobe) concerned with?
visceral sensations(sensations from the organs), autonomic control, interoception (understand what is going on inside you), auditory procession, visual-vestibular integration
what are the 3 layers of meninges?
dura, arachnoid, pia mater
what are the 2 divisions of the dura layer and what are they like?
periosteal- layer of periosteum
meningeal- durable, dense fibrous membrane
where is the CSF absorbed back into the blood stream?
arachnoid villi/granulations into superior sagittal sinus
What is the subarachnoid space and what is in it?
space in between the pia mater and arachnoid, CSF
what is the arachnoid like?
thin, transparent, fibrous membrane
what is the pia like?
thin, translucent and mesh-like
where is CSF produced?
in the choroid plexus of lateral, 3rd and 4th ventricles
what does CSF occupy?
subarachnoid space, ventricular system
how many ml of CSF is produced each day?
500
should CSF have blood and protein?
No blood
very little protein - 0.035 gm/dL
compare the following for CSF and Plasma: PH, Glucose, Proteins, sodium, potassium
PH:
plasma- 7.41
CSF-7.33
glucose:
plasma-90 mg/dL
CSF-60 mg/dL
Proteins:
plasma-7.0 gm/dL
CSF-0.035 gm/dL
Sodium:
Plasma-135 mEg/dL
CSF-135 mEg/dL
potassium:
Plasma- 5 mEg/dL
CSF- 2.8 mEg/dL
what is the difference between dorsal and ventral?
dorsal: towards the back
ventral: towards the front
what type of nerve modality is in the ventral side and dorsal side (root and rootlets)?
ventral-motor/efferent
dorsal-sensory/afferent
what is contained in grey matter?
collection of cell bodies
what is contained in white matter?
tracts that are going up and down and out
which is shorter, the spinal cord or the vertebral column?
spinal cord
how many vertebrae bones are there and how many pairs of nerves are there?
vertebrae bones-31
pairs of nerves-30
what are the 5 segments of the spinal cord and vertebrae column? and how many pairs of nerves are in each segment?
cervical- 8 thoracic-12 lumbar-5 sacral-5 coccygeal-1
what do nerves emerge through when leaving the spinal cord?
intervertebral foramina
between which 2 regions does the relationship between nerves and foramina change?
cervical and thoracic
which nerves emerge above vertebrae?
c1-c7
which nerves emerge below vertebrae?
c8-co1
what are the 2 spine enlargement and what do they innervate(going out and coming in)?
cervical enlargement- upper limbs
lumbar enlargement- lower limbs
what is the major DESCENDING pathway and what does it control ? what modality of neurons is present and where?
Corticospinal tract for VOLUNTARY movement
UPPER motor neurons.
corticospinal- primary motor cortex and spinal cord
corticobulbar- primary motor cortex and brainstem
what are the 2 major ASCENDING pathways and what are they in for?
dorsal column pathway- FINE touch(can localise stimulus), vibration, proprioception
spinothalamic pathway-CRUDE touch(can’t localise stimulus), pain and temperature
in terms of location, what are the 3 corticospinal and spinothalamic tracts and what do they control?
lateral corticospinal tract-motor
ventral/anterior corticospinal tract- motor
lateral spinothalamic tract-pain, temperature
ventral spinothalamic tract- crude touch
where are upper and lower motor neurons located and what does a lesion in each area result in?
upper motor neuron- pre central gyrus (motor cortex). lesion results in a stroke
lower motor neuron- spinal cord, or brain stem. lesion results in motor neuron disease.
what percentage of fibres in the corticospinal tract decussate?
85
where do 85% of the fibres of the corticospinal tract decussate?
medulla
what do the lateral and anterior corticospinal tract each innovate?
lateral(decussate)- limb muscles
anterior(ipsilateral/do not decussate)- trunk muscles
which muscles do the fibres that go through the following nuclei control? oculomotor, trochlear, trigeminal motor, abducens, facial, hypoglossal
oculomotor- extraocular muscles trochlear- extraocular muscles trigeminal-muscles of mastication abducens-extraocular muscles facial-muscles of facial expression hypoglossal-muscles of the tongue
does the corticospinal tract travel through the posterior or anterior limb of the internal capsule?
posterior limb of the internal capsule
what are the INVOLUNTARY motor tracts , where are they located and what do they each control?
located deep within the brainstem.
vestibulospinal- provides info about head movement and position and mediated postural adjustments
tectospinal- orientation of the head and neck during eye movements
reticulospinal- control of breathing and emotional motor function
rubrospinal- innervate lower motor neurons of the upper limb
in the dorsal column pathway, once fibres enter the dorsal horn, information conveyed in the LOWER LIMBS (below T6) travel ipsilaterally along which tract?
gracile tract
in the dorsal column pathway, once fibres enter the dorsal horn, information conveyed in the UPPER LIMBS (above T6) travel ipsilaterally along which tract?
cuneate tract
With ALL sensory pathways, the synapse between which two neurons causes the second neuron to cross to the other side of the body?
first and second neuron
in the sensory pathways, where is the cell body for the primary, secondary and tertiary neurons located? and use that to explain the difference between the spinothalamic and dorsal pathway.
primary cell body- dorsal root ganglion tertiary cell body- thalamus secondary cell body: spinothalamic- spinal cord dorsal-medulla
where do the fibres decussate in the corticospinal, spinothalamic and dorsal pathway?
corticospinal-medulla
dorsal-medulla
spinothalamic- spinal cord
where is the first synapse of the gracile tract?
where is the first synapse of the cuneate tract?
gracile nucleus
cuneate nucleus
finish the following sentences for the DORSAL pathway:
second order axons decussate in the ……?
from the…..?
synapse in the…..?
third order neurons from the thalamus project to the …?
size of the somatotopic areas is proportional to …?
caudal medulla contralateral medial lemniscus tract thalamus somatosensory cortex density of sensory receptors in that body region (somatosensory homunculus)
which pathway do pain and temperature ascend?
which pathway does crude touch ascend?
lateral spinothalamic tract
anterior/ventral spinothalamic tract
list the steps of the spinothalamic pathway.
primary afferent axons terminate upon entering the spinal cord
second order neurons decussate immediately in the spinal cord to form the spinothalamic tract. they terminate in the thalamus
if its pain and temp, it ascends the lateral spinothalamic tract
if it is crude touch, it ascends the anterior/ventral spinothalamic tract
third order neurons from the thalamus project to the somatosensory cortex
list the steps of the dorsal column pathway.
fibres enter via the dorsal horn and enter ascending dorsal column pathways.
information conveyed from the lower limbs and body (below T6) travel ipsilaterally along the gracile tract.
information conveyed from the upper limbs and body (above T6) travel ipsilaterally along the cuneate tract.
secondary order axons decussate in the caudal medulla.
they then synapse in the thalamus.
third order neurons from the thalamus project to the somatosensory cortex.
