brain: lobes, SC paths, Aa system Flashcards
visual system and tie to brain
optic nn from each eye carry the info of respective side-input from both used to construct image at the occipital lobe
cross over at optic chiasm
damage to nn ahead of chiasm-deficit in vision on that side
damage after that the chiasm- loss of that part of the world, not just vision= hemineglect
hemispheres/lobes
L and R hemispheres- comm via corpus collosum
each with 4 lobes: frontal, parietal, occipital, temporal
frontal lobe function
motor homunculus here ant to central sulcus
prefrontal cortex
Broca’s area
parietal lobe function
sensory homunculus post to the central sulcus
temporal lobe function
auditory cortex and assosiation cortex
weirnicke’s area
homunculi
4 total: 2 motor and 2 sensory
1 of each on each hemisphere
general layout of the homunculi
like upside down person with legs beginning at midline
broca’s and wernickies functions, mostly located where?
Broca’s: in the L frontal lobe, responsible for all motor production of language
Wernickie’s: in the L temporal lobe, responsible for the reception and understanding of written and heard language
majority of homunculus devoted to?
both motor and sensory have major devotions to our hands (sensation and fine motor control)
also large contributions to the face
spinal paths
dorsal column
spinothalamic
corticospinal
Pyramidal or Lateral Corticospinal tract
used for voluntary movement
impulse begins in the primary motor cortex= upper motor nn
moves down to cervical SC, signal crosses over at pryamidal dessucation
axon now in the corticospinal tract and down SC
enter the. grey matter at apporiate level and synapse with the Lower motor nn in ventral horn
Lower project axon to periphery to inn mm
Posterior Columns or Dorsal Columns
Vibration, Fine Touch and Position
sensation at peripheral processes>signal to cell body in the dorsal root ganglia
projects axon up to the medulla to synapse with secondary sensory nn
secondary sensory nn then projects axon across sensory decussation
axon then goes to the thalamus to synapse with third sensory nn
3rd will project axon to primary somatosensory cortex
Anterolateral or Spinothalamic tract
crude Touch, Pain, Temperature
sensation at periphrey sends signal to the cell body in the doral root ganglia
projects axon to synapse with second order nn in dorsal horn
2nd order will project the axon acress the ant commissure and to the contralteral anterolateral pathway
2nd order continues up to the thalamus to synape with 3rd order nn that then projects axon to the somatosensory cortex
Aa supply of the head
Int and ext carotid from the common carotid
int doesnt branch until in the skull
ext supplies mostly the face and scalp
vertebral aa
will move up the vertebral column into the foramen magnum and merge in the skull to form the basilar aa
what structures hitch a ride on the int carotid aa?
sympathetic nn fibers
entrance of the int carotid into the skull
enters through the carotid canal and passes over the foramen lacerum
will enter and twist several times before becoming the cerebral portion that join the circle of willis
int carotid gives rise to which aa?
mid and ant cerebral aa
label the following
label
ant cerebral supplies
middle aspects of the cerebral cortices
superior aspect of the midline as well
middle cerebral supplies
lateral aspects of the brain aside from the extreme superior, anterior, posterior and inferior portions
supplies a majority of the motor and sensory homunculi
post cerebral supplies
supplies the posterior aspect
inside temporal lobe and its inferior aspect
redundant flow of the circle of willis
can allow for redundancy in the flow despite blockages within the circle
this can prevent the loss of nn due to lack of blood flow
hydrocephalus, adult vs baby?
can be due to blockage or stenosis of a foramen in the ventricular system
continued CSF produced despite the blockage=back up of CSF and increased intracranial pressure
babies heads can expand and compensate for this but adults cannot which can lead to deficits
aneurysms, treatment
usually occur where vessels converge with one another
weakened vessel walls allow for the increased pressure to cause a berry to form>further increased pressure can lead to rupture of this berry and loss of blood flow, could be a stroke in the brain
treated with clipping/coiling to reduce possibility of rupture if found early
