Phsio Review Stuff Flashcards
pyramidal tracts
= cortispinal + corticobulbar tracts
- CS tracts (mvmt of mm. of body): primary motor cx –> axons descend down puramidal tracts and travel through cx through posterior limb of IC, cerebral peduncle and decussate in pyramids –> run in contralateral lateral corticospinal tract (anterior horn)
- corticobulbar tracts (mvmt of mm. of head): fibers from ventral motor cx travel with CS tract through internal capusle but terminate in pons, medulla oblongota and midbrain — synapsing with cranial nerve nuclei
- nuclei are supplied by nerves from both side of brain, except from facial nn that controls lower half of face
- these mm. are only innervated by nn. from c/l side of cx!
(thus if 1/2 of tract is damaged then only lower face on opposite side will be affected)
extrapyramidal system
rubrospinal tract
recticulospinal tract
lateral vestibulospinal tract
tectospinal tract
- causes involuntary reflexes and mvmt and modulation (i.e. coordination) complex mvmts and are modulated by the basal ganglia, cerebellum as well as cerebral cx
If you were to lesion the corticospinal pathway you would at first have paralysis, however later the extrapyramidal pathways would kick in (rubrospinal, vestibulospinal, reticulospinal, tecospinal) – and you would gain control over your limbs
• reticulospinal tract – has most plasticity when corticospinaltract is lesioned
• rubrospinal tract – fine motor mvmt in the hands
• vestibulospinal tract – necessary for posture
• tectospinal pathway – reflexive neck mm. of posture/grasp reflex
brain dev?
prosencephalon –> telencephalon = cx and BG - CN1
prosencephalon –> diencephalon = thal and hypothal. - CN2
mesencephalon –> midbrain- CN3,4
rhomboencephalon –> metencephalon = pons/cerebellum - CN5,6
rhomboencephalon –> myelencephalon = medulla CN7-12
Broca’s aphasia
opercular part of left frontal lobe- motor of speech
“expressive aphasia”
Wernicke’s aphasia
parietal lobe (supramarginal and angular gyrus) + temporal lobe (superior gyri) "language comprehension"
temporal lobe
- higher order visual processing - i.e. facial recognition
- learning and memory (hippocampus located deep to here)
- primary auditory cx
- Wernicke’s area
occipital lobe
primary visual cx
limbic system
= papez circuit - emotions and memories
- cingulate gyrus → parahippocampal cx → hippocampus → fornix → mammillary bodies → anterior nucleus of the thalamus → cingulate gyrus
- this is forming and storing and distributing of memories through this pathway
hemineglect
right side parietal lesion - results in inability to see the left side of your world
visual world?
** occiptal lobe **
cuneus = info from interior part of field
lingual gyrus = info from superior part of field
inferior colliculi
hearing/localizing sound
midbrain
superior colliculi
seeing and moving eyes/tracking
midbrain
DCML
carries proprioception, fine touch, vibration sense – sensory info!
- cell body located in dorsal route ganglion
- enters into dorsal horn and goes into dorsal columns (posterior funinculus)
- if arm: ends up laterally in fasciculus cuneatus
- if leg: ends up medially in fasciculus gracilis
- ascends to the nucleus cuneatus/gracilis in the caudal medulla where is synapses on a prethalamic relay neuron
- secondary neuron then dcussates at the internal arcuate fibers of the medulla and ascends through the pons in the medial lemniscus
- It synapses in ventral posterolateral nucleus of thalamus (VPL) (medial arm, lateral leg)
- Third neuron ascends through the internal capsule to the somatosensory cortex.
Lesion of DCML:
- ispilateral loss of vibratory sense, position sense and discrimitive touch below level of lesion (stereoanesthesia)
- rostral to decussation, medial lemniscus lesions result in contralateral losses that include the entire body excluding the head.
ALS
Anterolateral System (ALS:) carries pain, temp, crude touch
- primary affarents come in to dorsal horns where they synapse on secondary neurons.
- they give off a motor neuron here to control reflex
- second neurons ascend in in tract of lissauer (posterolateral tract) prior to decussation for a few levels.
- they then will decussate through the anterior white comissure and will join the anterolateral system.
- the spinothalamic tract with synapse on the VPL , ascends through internal capsule to eventually react the somatosensory portion of the cortex
4 tracts of ALS?
Four Tracts of the ALS?
1. spinothalamic (projects to primary SS cx via thalamus - conscious perception):
• runs unilaterally, has good localization
2. spinoreticular tract (focus attn):
• projects to reticular formation: important in alerting cx and focusing attn. on noxious stimuli
3. spinomesencephalic tract (pain modulation): goes to midbrain
• info sent to periaqueductal grey (group of neurons near mesocephalic aquduct) which helps regulate pain modulation
• subset spinotectal tract: sends info from spinal cord to superior colliculus which functions in visual reflexes: when noxious stimulus comes in - focus eyes there “visual reflex”
4. spinohypothalamic tract (autonomic and emotional response)
• - projects to hypothalamus
• - carries autonomic responses to stimuli
• - projects to limbic system so that there is an emtotional response to pain
4 spinocerebellar tracts?
- Cuneocerebellar tract = fine proprioception in upper half of body
- DSCT: used for fine unconscious proprio of lower half
- VSCT: used for gross unconscious proprio – this one decussates twice, none of the others decussate
VTT
Pain, Crude touch, temp:
o primary affarent cell bodies located in trigeminal ganglion.
o The fibers then enter the pons via the trigeminal nerve and descend to the medulla via the spinal tract of V. where they synapse with second order neurons at spinal nucleus of V.
o second order neurons then will ascend and decussate in medulla and ascend through the pons to the ventral trigeminal thalamic tract (VTT) and eventually synapse in VPM of the thalamus.
o third order neuron will then travel out to the lateral cortex.Proprioception: cell body located in mesencephalic nucleus of V, synapses on pontine nucleus of V and ascends through ventral trigeminal thalamic tract to the VPM of thalamus
• NOTE: this information is joined along the way by pain and temp from ear from VII, IX, X
• Thus spinal trigeminal tract contains VII, IX and X pain fibers as well!
Vibration and fine touch/two point:
- cell body located in trigeminal ganglion, synapses on pontine nucleus of V (main nucleus), then decussates in the DTT to the VPM where it synapses on third order neuron
Proprioception:
o proprioceptive primary affarent fibers enter the pons and ascend to the mesencephalic nucleus of V where they leave their cell bodies, then return back to the pontine nucleus of V where they synapse on second order neurons.
o The second order neurons project up contralaterlly through the VTT to eventually synapse on third order neurons of VPM, they are then sent out to post-central gyrus.
dorsal trigeminothalamic tract
Basic touch and two point info of the head ascends *bilaterally in two pathways
• two point discrimination of face ascends bilaterally through this tract!
• mouth ascends ipsilaterally – inside mouth stays ipsilateral
• the rest of the face ascends contralaterally
o enters into the pons, neuron synapses on two different sides in the pons at the pontine nucleus of V or the “main nucleus”
o the mouth ascends ipsilaterally, the contralateral side is the rest of the face
hippocampus
how memories are consolidated and stored
• inside hippocampus you are storing memories à entorhinal cortex à dentate gyrus à CA3 à CA1 à subiculum → entorhinal cortex
• this is short term working memory – as long as its traveling in this loop its easily accessible, but isn’t processed yet
• people in alzheimers have hippocampal neuron degeneration earlier, they have no short term working memory
corticospinal pathway
= pyramidal tract
= complex fractionated movement of the limbs = motor control
Cortical input from primary motor cortex and premotor cortex
• descends through corona radiate and then the IC → cerebral peduncles → basal pons → pyramids of medulla → decussates at the pyramidal decussation
• descends contralaterally in the lateral corticospinal tract
corticobulbar pathway
= mm. of facial expression and chewing
• cortical input from precentral gyrus descends through IC and synapses bilaterally on many nucleus
o note: there is a branch off of the corticobulbar tract: allowing contralateral mm. control of mouth down, but bilateral control of the eyes
o note: occulomotor nuclei are not part of this tract, III, IV and VI can still be activated separately
cerebellum cells
• mossy à granules à parallel à purkinge à deep cerebellar nucle
o fibers entering the cerebellum are called “mossy fibers” – they ascend and synapse on granule cells
o granule cells will then bifurcate to form parallel fibers
o parallel fibers then synapse on purkinje cells
o purkinje cells synapse on deep cerebellar nuclei (emboliform, dentate, fastigial, globose)
• inferior olive sends contralateral projection to cerebellum that gives cerebellum a metronomic beat – cerebellum interprets through this time frame, and determines the timing of movements
o climbing fibers, coming from inferior olive wind around the purkinje cells and synapse onto the purkinje cells as well
• thus purkinje cells are the meeting place – receive input from spinal cerebellar input from granule cells along with from the inferior olive
hippocampal pathway
- inside hippocampus you are storing memories à entorhinal cortex à dentate gyrus à CA3 à CA1 à subiculum → entorhinal cortex
- this is short term working memory – as long as its traveling in this loop its easily accessible, but isn’t processed yet
- people in alzheimers have hippocampal neuron degeneration earlier, they have no short term working memory
how does transduction occur? pathway of light?
light causes isomerization of 11-cis retinal –> 11-trans retinal
activates transducin
which results in activation of cGMP phosphodiesterase hydrolyzing cGMP to GMP
results in hyperpolarization of the membrane d/t closing of Na+ channel!!!
** pathway of light **
light travels in all the way to the deepest portion of retin to the photoreceptor cells –> synapse on bipolar cells –> synapse on ganglion cells of the optic n. fibers –> synapse at LGN –> synapse at primary visual cortex
different retinal ganglion cells that project to difft. parts of LGN?
P cells= detail/color (layers 3-6)
M cells = basic motion (layers 1,2)
Layers 1,4,6 = c/l
layers 2,3,5 = ipsi
damage to left optic nn. directly at entrance in eye (i.e. in MS)
= left central scotoma
loss or right optic nerve
blindness of right eye
pituitary tumor
lesion at optic chiasm, where the outer visual fields decussate –>ipsilateral bitemporal hemianopsia = “tunnel vision” - lose outer most fields of vision
lesion of right optic tract
causes contralateral homonymous hemianopsia = loss of left side of both vision fields
lesion of right optic radiation in meyer’s loop
meyer’s loop carries info of superior visual world and located in inferior lingual gyrus
results in left superior quadtrant anopia (loss of superior contralateral visual field)
lesion of right optic radiation in Baum’s loop
baum’s loop carries info of inferior visual world and located in superior cuneus gyrus
results in left inferior quadrant anopia (infeiror portion of contralateral visual field is impaired)
lesion of right optic radiation
if both are lesioned results in similar finding to that of optic tract lesion = contralateral homonymous menionopsia
lesion to optic tract when someone falls and hits their head
hits back of head and primary digital cortex/occipital lobe - might result in bilateral central scotoma = loss of central foveal visual fields
central auditory pathway
** note sound from each ear travels bilaterally, so that it can be compared in order to localize the sound
• enters through CN VIII and synapses on cochlear nuclei. It then ascends bilaterally to the superior olive
• from superior olive there is communication and then ascends through lateral lemniscus to inferior colliculus
• then to the medial geniculate nuclei and to the primary auditory cortex
know basal ganglia!
look at it now.
wallenburg syndrome
stroke of PICA = lateral medullary syndrome
Ipsilateral loss of Pain/Temp in the face
Contralateral loss of Pain/Temp in the body
