Cerebral cortex

cerebral cortex

highest level of all sensory and somatic motor control

memory, association, cognitive processes

control neural activity

4 lobes

frontal

parietal

temporal

occipital

angular gyrus

language processing

can be found at the end of the lateral sulcus

premotor cortex

it’s an area

motor planning

locate to the left of pre central gyrus (primary motor cortex) and under the suppl. motor area

supplementary motor area

move based on memory (“muscle memory”)

ex: piano player

located superiorly and left to the pre central gyrus

main long tracts (pathways)

• posterior column-medial lemniscus pathway

• anterolateral pathway

• lateral corticospinal tract

posterior column - medial lemniscus pathway

main somatosensory pathway

vibration, proprioception, tactile discrimnation

contralateral

crosses at the medulla

• all external sensations are sent to the dorsal ganglia in the spinal cord → posterior dorsal columns → primary sensory neuron → brain → medulla → crosses over to the other side of the medulla → goes to the secondary sensory neuron (medial lemniscus) → thalamus (ventral posterior lateral nucleus (VPL)) → post-central gyrus (primary somatosensory cortex)

anterolateral (spinothalamic) pathway

main somatosensory pathway

contralateral

crosses at the spinal cord

pain, temperature, crude touch

sensory sent to dorsal root ganglion → primary sensory neuron → spinal cord → crosses anteriorly of spinal cord → anterolateral pathway (spinothalamic tract) → brain → 2nd sensory neuron → thalamus (VPL) → primary somatosensory cortex

Brodmann’s area

in the occipital lobe:

area 17: primary visual cortex / striate cortex - V1. most caudal of the lobe

area 18 and 19: extra striate cortex - V2. more rostral of the lobe

cortical spinal tract

aka pyramidal tract

contralateral

DORSAL ROOT GANGLION DOES NOT INVOLVE

sensory sent to the lower motor neuron in spinal cord → upper motor neuron → lateral corticospinal tract (by the cervical) → brain → cross at the lower part of the medulla → precentral gyrus (motor cortex)

hem-cord lesion

aka Brown-Sequard syndrome

ipsilateral effect: motor loss, proprio (sense of position) loss, vibration

contralateral effect: pain and temp

pre central gyrus

primary motor cortex

contralateral

post central gyrus

primary somatosensory cortex

somatosensory and motor homunculus

frontal lobe

body movement, speech (Broca’s), saccadic eye movement, personality/judgement/planning/reasoning

parietal lobe

somatosensory, pursuit eye movement, spatial attention

occipital lobe

vision

temporal lobe

memory, hearing, language comprehension (Wernicke’s), facial/object recognition

primary visual cortex

occipital lobe

visual field analysis

contralateral

calcarine fissure

separate the lingual and cunneas gyrus

lingual gyrus

process superior quadrant of VF

contralateral

ex: L lingual allows for R superior VF

R lingual allows for L superior VF

cunneas gyrus

process inferior quadrant of VF

contralateral

ex: L cunneas allows R inf quad VF

R cunneas allows L inf quad VF

frontal eye field

FEF

contralateral

saccadic eye movement = rapid eye movement

when damage, cannot make saccade to the other eye

located left of the pre motor cortex

Parietal-occiptal-temporal cortex

ipsilateral

aka POT

smooth pursuit eye movement (allow eyes to follow an object)

locate at where all 3 lobes meet

Broca’s

speech formation

locate in the frontal lobe, above the lateral sulcus

Wernicke’s

language comprehension

located in the temporal lobe

right under the lateral fissure, sometimes look like a W

Heschl’s gyrus

primary auditory cortex = hearing

bilateral = when only L side is affected, the person can still hear from the R ear.

located temporally across from the insular cortex (in temporal lobe) where the ears are

insular cortex

taste

located behind the lateral fissure

which hemisphere is dominant for language?

Left

olfactory pathway

does not go thru the thalamus

olfactory receptors in nasal mucosa (nose- → olfactory bulb → olfactory tract → lateral olfactory stria → primary olfactory cortex (at/near uncus) →orbitofrontal olfactory area

olfactory receptors in nasal mucosa (nose) → olfactory bulb → olfactory tract → medial olfactory stria → contralateral olfactory bulb

anosmia

loss of smelll

uncus

in the temporal lobe

in charge of memory

Foster-Kennedy syndrome

Symptoms:

• ipsilateral: optic atrophy (pale) in 1 eye → reduced VA

• contralateral papilledema: swollen optic nerve on the other eye → due to increased IOP unaffected VA

Causes: anterior cranial fossa meningioma

dead optic nerve can’t swell !!! *

healthy optic nerve: pick, reddish

pale optic nerve: white, white-ish

optic atrophy: dead optic axons → pale looking

spatial neglect

pt tend to neglect the entirety of a side (L or R) due to a damage of the contralateral side of the parietal lobe.

palinopsia

an object that you had seen persist in your vision.

trailing is an example.

ex: you are looking at an apple in front of you, then you look away and you still see that apple.

Alice in wonderland

objects appear unusually smaller or bigger than it actually is

corpus collossum

front to back: rostum, genu, body, splenium

the selenium is the part that connects the occipital lobe

split-brain patients

pt have gone under sx to cut the corpus callosum

left hemisphere: dominant for verbal processing

a pt is shown the word “face” to his right VF → can say “face”

he is now shown to is right VF → can only draw a face but unable to say it

→ the right hemisphere sees the word, but cannot communicate w the left side to form speech.

neocortex

6 layers of the cerebral cortex

• IV receives thalamic info

• VI sends feedback to thalamus

• V sens output to spinal cord, brainstem, and basal ganglion