Neuro anatomy Clinical skills Flashcards
what structures make up the CNS
Brain/spinal cord
what structures make up the PNS
peripheral nerves
what is the cauda equina
region where spinal roots/nerves start traveling down the spinal canal and the spinal cord itself ends
happens around L1/L2 region
What percentage of blood in the body is sent to the brain, and why is that important
20% of blood
any blockages can result in significant damage very quickly
what are the 3 parts of the brainstem, in decending order
midbrain
pons
medulla oblongata
What is the homonculus?
parts of the brain that correspond to the human body, with the innermost parts of the somatosensory and motor cortexes representing the feet and the bottom of the body, and moving up the body as you move laterally in the brain
areas with larger sensory input/tactile receptors take up larger areas on the homunculus
What are the 4 lobes, and the primary cortexes in each lobe?
frontal - primary motor cortex (motor movement initiation and planning)
parietal - somatosensory cortex (sensory input processing from sensory input)
temporal - primary auditory cortex (hearing input)
occipital - primary visual cortex (visual input)
What is the main blood supply for the frontal lobe? what would happen to the frontal lobe function if there were a stroke?
blood supply - Anterior cerebral artery (lower body) and middle cerebral artery (upper body)
impairments - inability to move lower/upper body, alongside issues arising with planning of voluntary motor movements. may also result in issues with processing information/solving problems, and if MCA stroke there will be deficits with speech production
what is the frontal lobe responsible
planning voluntary movement and controlling learned motor skills
executive functioning
controls expressive motor behaviour (hand gestures, facial expressions)
contains Broca’s area
what is the brocas area
responsible for the production of speech
brocas aphasia - inability to produce speech
What is the main blood supply for the parietal lobe and what would happen to the parietal lobe if it gets blocked
blood supply - Anterior cerebral artery (lower body) and middle cerebral artery (upper body)
impairments - inability to have sensation of lower/upper body, alongside issues with proprioception. may also result in issues with spatial memory and mathematical skills.
some minor language comprehension impairments as wernikes area is split between temporal and parietal
what is the function of the parietal lobe
sensory information interpretation and processing, alongside proprioceptive interpretation.
influences math skills and some language comprehension, and stores spatial memories to allow people to orient themselves and maintain sense of direction
what supplies blood to the occipital lobe of the brain and what happens to occipital lobe function if the vessel is blocked?
posterior cerebral artery
issues with vision, leading to blindness, issues with differentiating colour, hallucinations,
what is the occipital lobe responsible for
visual interpretation and visual memory
what supplies the temporal lobes with blood and what would happen to their function if it was blocked
middle cerebral artery
issues with memory and emotions
inability to understand/recognize people, objects, or sound
inability to understand speech due to wernikes area being impacted
what is wernikes area
region in the brain responsible for the comprehension of speech
what is the function of the parietal lobes
generation of memory and emotions, processing of hearing and comprehension of speech
processing of events into LTM and retrieval of memories
recognition of objects and people
What makes up the Diencephalon
Limbic system (experience and expression of emotions like fear, anger, pleasure)
Hippocampus - formation and retrieval of memories for connection to emotions
Thalamus - relays all sensory information to and from the brain (besides olfactory input)
hypothalamus - coordination of autonomic functions of the body and linking of nervous system to endocrine system
basal ganglia (caudate nucleus, putamen, and globus pallidus) - coordinates and smoothens movements - impaired in those with Parkinson’s or Huntingtons
What are the functions of the thalamus
learning of motor activities, sensory information relay, and minor role in memory development
what are the functions of the hypothalamus
autonomic control centre
centre for emotional response
regulation of body temp
regulation for hunger/thirst
regulation of sleep cycles (contains ‘wake-up’ centre which is inhibited/disinhibited as per the midbrain)
control of endocrine function
emotional responses
What is the function of the midbrain
pass point of all sensory input on the way to the thalamus, involved in
voluntary movement
motor functions
coordination of visual/auditory reflexes
circadian rhythm regulation (controlling the transition between sleep and wake)
and thermoregulation
what are the functions of the pons
control of sleep, respiration, swallowing,/taste, bladder control, equilibrium, facial expression/sensation, and posture
what are the functions of the medulla oblongata
decussation point for corticospinal and posterior column tracts
regulation of autonomic function (respiratory rhythm, cardiofunction, etc) and reflexes (cough, vomit, swallowing)
What are the 3 meninges layers
Pia mater - innermost layer
Arachnoid Mater - middle layer
Dura Mater - outermost and toughest layer
WHat is the meninges
layers of tissue meant to protect the brain and spinal cords
What is cerebrospinal fluid
fluid that surrounds the brain and spinal cord, removes toxins and enters the spinal cord through the ventricles
also allows the brain to float, resulting in less overall weight of the brain and ensuring that the brainstem is not crushed under the weight of the brain
What is a spinal fluid tap?
Collection of CSF from the lumbar region (as its the bottom of the spinal cord)
Indicates the overall health of CSF
WHat is hydrocephalus
when there is a block in the ventricles of the brain, leading to swelling of the brain due to excess CSF
stent usually placed to release pressure
what is the strength of a muscle contraction proportional to?
the number of motor units recruited
What roots do the sensory and motor tracts exit the spinal cord through
dorsal - sensory
ventral - motor
peripheral nerve - mixed
where are the cell bodies located for the motor and sensory roots
sensory - in dorsal root ganglion
motor - in the spinal cord
what is the difference between white matter and grey matter in the spinal cord
grey matter - contains cell bodies and dendrites, allows neurons to transmit info between each other (also where spinothalamic tract decussates)
white matter - bundles of axons to send info up/down the spinal cord (aka spinal tracts)
What info do ascending and descending tracts carry
ascending - sensory info
descending - motor info
what are interneurons in the spinal cord for
bypassing the typical sensory tracts and connecting directly to the motor roots in order to trigger somatic reflexes
what is the difference between the dorsal and ventral rami in spinal nerves
dorsal - info to/from posterior muscles/skin
ventral - info to/from anterior muscles/skin
what are the 4 primary plexuses
Cervical
brachial
lumbar
sacral
what is a dermatome
region of skin innervated by a single spinal nerve (some overlap does exist)
VZV virus caused by chickenpox can damage DRG and this can lead to pain/rash in a specific dermatome
what is the function for all 3 orders of sensory neruons
1st - sensory input to point of decussation
2nd - decussation to thalamus
3rd - thalamus to cortical cortex
Describe the posterior column tract
responsible for sensory info for fine touch, proprioception, and vibration
1st order - sensory input to gracile in medulla
2nd order - decussation in medulla and ascend to thalamus
3rd order - thalamus to somatosensory cortex
Describe the spinothalamic tract
responsible for sensory info for pain, temperature, and itchiness
1st order - sensory input to grey matter of spinal cord
2nd order - decussation in SC and travel up white matter to the thalamus
3rd order - thalamus to somatosensory cortex
Describe the corticospinal tract
motor pathway that descends down the SC, below is the pathway
motor cortex
corona radiata
internal capsule
cerebral crus
midbrain/pons
decussation in medulla oblongata
travel down spinal cord white matter
synapse onto lower motor neurons
Describe the corticobulbar tract
cerebral cortex to medulla oblongata
What is the corpus callosum
white matter that transfers info between brain hemispheres
Describe upper motor neuron damage
muscle paresis/paralysis
increase in tone
hyper reflexivity
increase in spasms
weakness, but no muscle wasting
opposite side
describe lower motor neuron damage
weakness/paralysis
muscle wasting
flaccid paralysis (low tone)
negative Babinski test
same side
what are some ways that you can get neurological damage
toxins
pressure
heat
cold
inflammation
tumors
genetic diseases
infection
developmental damage
environmental damage
trauma
transmission
idiopathic
why is demyelination of nerves bad
myelin promotes nerve conduction by forcing impulses to jump across nodes of ranvier, without myelin signals slow down and may not make it to the muscle, resulting in denervation of muscles
multiple sclerosis causes this
