Neuro summary points Flashcards
Summarise blood supply to head and neck
- Common carotid artery
- —-> external carotid artery
- —-> internal carotid artery - Subclavian artery
- —-> vertebral artery
anterior blood supply to brain via
carotid artery
posterior blood supply to brain via
vertebrobasilar artery
what structure divides the lobes of the brain
central sulcus
in one word summarise the role of frontal lobe
thinking
in one word summarise the role of parietal lobe
feeling
in one word summarise the role of the temporal lobe
hearing
in one word summarise the role of the occipital lobe
seeing
what makes up the peripheral nervous system?
- cranial nerves
2. peripheral nerves
summarise the enteric nervous system?
- digestive nervous system
- peristaltic contractions
- interstitial cells of cajal are the pacemaker cells
what are the pacemaker cells in the enteric nervous system known as?
- interstitial cells of cajal
Describe divisions of the nervous system?
- Autonomic (involuntary)
- —> sympathetic
- —> parasympathetic - Somatic (voluntary)
- —> muscular sensations
describe actions of the sympathetic nervous system (4)
- increase HR
- Vasoconstriction
- Bronchodilation
- decreased digestion
describe actions of the parasympathetic nervous system?
- decrease HR
- decrease sweat
- increased digestion
- Vasodilation
via ACH action on muscarinic receptors
state the lateral corticospinal tract
limb motor control
state the ventral corticospinal tract
axial motor
state the lateral spinothalamic tract
pain and temperature
state the anterior spinothalamic tract
crude touch
what is the anterior white commissure?
- where decussation occurs
- axons cross over
Dorsal column medial lemniscus pathway is for
fine touch
propioception
what makes up the dorsal column?
gracile and cuneate nuclei
where do the fibres deccusate in the dorsal column?
medulla oblongata
after decussation where do the fibres travel in the dorsal column?
- internal arcuate fibres
- medial lemniscus
- synpase onto ventroposterolateral nucleus
- in the post central gyrus
3 main neurons involves in the dorsal column medial lemniscus pathway?
- dorsal root ganglion
- cuneate / gracile nucleus
- ventral posterolateral nucleus (thalamus)
spinothalamic tract handles
- pain
- temperature
- crude touch
describe lissauers tract?
- route by which the spinothalamic tract ascends or descends
describe the path of neurons in the spinothalamic tract?
- first order neuron (afferent)
- can ascend of descend 1 or 2 levels within lissauers fasiculus
- synapses in dorsal horn of grey matter
- decussation (2nd order neuron)
- ascends via spinothalamic fasiculus
- to brain stem (aka anterior white commissure)
- to thalamus
- 3rd order neuron to post central gyrus (primary somatosensory cortex)
what is the primary motor cortex ?
pre-central gyrus
describe the corticospinal tract path ? (7)
- pre-central gyrus
- descends via internal capsule
- leaves via brainstem
- (thalamus not involved)
- to midbrain, pons, medulla
- in medulla 75-90% fibres decussate (limb innervation)
- ——-> decussation of the pyramids - the remaining 10-25% are axial fibres which don’t decussate here!
describe what happens to the remaining 10-25% of fibres which do not decussate in the medulla in the corticospinal tract?
Anterior Fibres
- fibres run down corticospinal tract
- —> either anterior
- —> or lateral - at target level fibres in anterior spinothalamic tract will decussate
- through anterior white comissure
- before synapsing to a neuron
- in anterior horn of grey matter
- anterior horn cells will project to anterior limb and axial muscles
what occurs to lateral fibres in the corticospinal tract?
- lateral corticospinal tract fibres have already decussated at level pf pyramids
- so at appropriate level
- will synapse onto neuron
- in anterior horn
compare upper vs lower motor neurones?
Brain ————————————} UPPER MOTOR NEURON
spinal cord —————————-} UPPER MOTOR NEURON
anterior horn cell ——————-} LOWER MOTOR NEURON
target muscle ————————} LOWER MOTOR NEURON
Describe upper motor neuron lesions signs?
- spastic (spasm)
- hypertonic muscles
- hyperreflexic
- disuse atrophy
- positive babinski
- muscle becomes hypertonic first before atrophy
describe lower motor neuron lesion signs?
- flaccid (limp)
- hypotonic
- hyporeflexic (not present)
- denervation atrophy
- negative babinski
- lose innervation so atrophy early on
what occurs in upper motor neuron lesions?
- lose ability to send signals to anterior horn
- unregulated innervation
- spasm
what occurs in lower motor neuron lesion?
- lesion to anterior horn cell OR nerve projecting from anterior horn cell to muscle
- e.g nerve crush injury
- flaccid
- atrophy
Basal ganglia are involved in ….
- movement
- fine tuning
- e.g. your petting a dog, you don’t want to be petting too hard
- does this by amplifying and diminishing some movements
What makes up the basal ganglia?
- Putamen
- caudate nucleus
- Globus Pallidus (2 parts)
- Substania nigra (2 parts)
- subthalaic nucleus
what makes up the neostratium?
- putamen
2. caudate nucleus
describe the different pathways that the basal ganglia use?
- Direct pathway
- —> facilitates purposeful behaviour and movement - Indirect pathway
- —> inhibits unwanted movements
what is contained in the internal capsule?
white matter tract
direct pathway involves (4)
Comes Straight Into Thalamus
- Cortex
- striatum
- globus pallidus internus
- thalamus
describe the indirect pathway? (6)
Comes Straight, Exits, Sidesteps Into Thalamus
- Cortex
- Striatum
- External Globus Pallidus
- Subthalamic nucleus
- Internal globus pallidus
- Thalamus
Initial signal from motor cortex comes from ….
Striatum
1—–> caudate
————–> cognitive memory
2—–> putamen
—————–> motor function
Putaminal haemorrhage would result in….
- weakness
- paralysis of muscles throughout body
Describe two parts of the globus pallidus?
- Internal (inhibitory)
2. External (Excitatory)
Describe the role of the subthalamic nucleus?
- produces excitatory neurotransmitters
- ultimately produces an inhibitory effect
What is hemi ballismus
- erradic movement of limbs
- after subthalamic nucleus damage
Describe the substantia nigra in the midbrain?
- dopamine
- facilitates movement (fast, fluent, smooth)
- like oiling a door
reduced production of dopamine in susbtantia nigra would result in?
- e.g. parkinsons
- muscle stiffness rigidity and slowness
role of internal capsule?
- bypasses the basal ganglia and goes straight to muscle
- has an anterior and posterior limb
- genu in middle
- kinda looks like a boomerang
describe posterior limb of internal capsule?
- corticospinal tract
- injury here could lead to contralateral hemiparesis, or hemiparalysis
describe the genu in the internal capsule?
- bend
- contains the corticobulbar tract
- travels to muscles in face
Role of reticular formation
- decides which sensory info gets sent to brain
- filters out irrelevant stimuli
Summarise the role of the pons?
- Pontine resp centre (rate and depth of breathing)
- ———-> pneumotaxic (inhibits exp)
- ———-> apneusitic (promotes insp) - Ocular movement
- Neurotransmitter production
- ———> raphi nuclei (serotonin)
- ———> locus coeruleus (norepineprhine)
Medulla oblongata key areas and roles
- Area Postrema —> vomitting
2. Nucleus solitarus —> gag reflex, tongue, BP, baroreceptor reflec
So a loss of taste and problems in maintaining BP may suggest a lesion in where?
- lesion in nucleus solitarus
2. nucleus sole-lick-tarus, would make ya wanna gag
lesion in nucleus ambiguus would lead to?
- dysphagia
2. dysarthrita
Pyramidal decussation occurs at…
end of medulla
Lambert-Eaton syndrome
- autoimmune
- peripheral muscles affected
- antibodies to calcium channels at neuromuscular junction
- type 2 hypersensitivity
- may present after small cell carcinoma
