Mkgrady8 Neuro 4 Brain Stem Lesions

Front 1

medial medullar lesion causes what and what is occluded

Back 1

called medial medullary syndrome; due to anterior spinal artery occlusion; both contralateral spastic paresis (corticospinal) and contralateral loss of tactile, vibration, proprioception (medial lemniscus); ipsilateral flaccid paralysis of tongue with tongue deviation on protrusion to lesion side

Front 2

lateral medullary syndrome causes what and what is occluded

Back 2

PICA is occluded; contralateral loss of pain+temp (spinothalamic tract); ipsilateral horner's syndrome (hypothalamic tract); vestibular nuclei so vertigo and nystagmus (away from lesion); nucleus ambiguus (mostly notice 10) so ispsilateral hoarseness, nasal voice, loss of gag reflex, etc; spinal 5 so ipsilateral loss of pain and temp; maybe some ipsilateral limb ataxia due to inferior cerebellar peduncle damage

Front 3

medial pontine syndrome causes what and what is occluded

Back 3

lesion in paramedian branches of basilar artery; contralateral spastic hemiparesis and contralateral loss of sensation; medial strabismus due to damage of CN6

Front 4

lateral pontine syndrome cases what and what is occluded

Back 4

lesion of AICA; loss of pain and temp on contralateral side; ipsilateral horner's syndrome; vestibular nuclei so vertigo and nystagmus (away from lesion); CN7 so ipsilateral facial paralysis; spinal trigeminal nucleus and tract so ipsilateral loss of pain and temp from face; cochlear nucleus so ipsilateral hearing loss

Front 5

pontocerebellar angle syndrome: caused by what, what does it do

Back 5

usually caused by an acoustic neuroma (schwannoma) of CN8; slow grogin tumor which originates from schwann cells in the vestibular nerve (or less commonly the auditory nerve); as the tumor grows it exerts pressure on the lateral part of the caudal pons where CN7 emerges and may expand anteriorly to compress the 5th nerve; the CN deficits seen together localize the lesion to the brain stem but the absence of long tract signs indicates that the lesion must be outside of the brain stem; NOTICE NO LONG STRACT SIGNS BECAUSE THIS IS NOT IN THE BRAINSTEM

Front 6

medial midbrain syndrome causes what and what is occluded

Back 6

occlusion of posterior cerebral arteries; contralateral spastic hemiparesis; damage to CN3 so ipsilateral oculomotor palsy (ptosis, mydriasis, external stabismus); damage to corticobulbar tract so contralateral spastic hemiparesis of lower face

Front 7

dorsal midbrain syndrome causes what and is an occlusion of what

Back 7

aka parinaud syndrome; this is due to a pineal region tumor; superior colliculus/pretectal area damage so paralysis of upward gaze, various pupillary abnormalities; cerebral aqueduct occlusion so noncommunicating hydrocephalus

Front 8

what are the 3 reticular nuclei

Back 8

raphe nuclei; locus ceruleus; periaqueductal gray

Front 9

raphe nuclei: where are they, what do they do

Back 9

narrow column of cells in the midline of brain stem; extending from the medulla to the midbrain; dorsal raphe nucleus synthesize serotonin

Front 10

locus ceruleus: what is it, what does it do

Back 10

synthesize norepi and send projections to mostbrain areas involved in the control of cortical activation (arousal)

Front 11

periqueductal gray: what is it, what does it do

Back 11

collection of nuclei surrounding cerebral aqueduct in the midbrain; opioid receptors are present on many periaqueductal gray cells (suppress a painful stimulus from spinothalamic tract)

Front 12

cerebellum: derived from what, consists of what, does what

Back 12

derived from the metencephalon; consists of a midline vermis and 2 lateral cerebellar hemispheres; the cerebellar cortex consists of multiple parallel folds (folia); contains several maps of the skeletal muscles of the body; the vermis controls the axial and proximal musculature of the limbs, the intermediate part of the hemisphere controls distal musculature, and the lateral part of the hemisphere is involved in motor planning; the flocculonodular lobe is involved in control of balance and eye movements

Front 13

vermis and intermediate zones: function and principle input

Back 13

function= ongoing motor execution; principle input= spinal cord (info from muscle spindles)

Front 14

lateral hemisphere: function and principle input

Back 14

function= planning and coordination; principle input= cerebral cortex and inferior olivary nucleus

Front 15

flocculonnodular lobe: function and principle input

Back 15

function= balance and eye movements; principle input= vestibular nulcei (CN8)

Front 16

major inputs to the cerebellum travel in through what

Back 16

inferior and middle cerebellar peduncles

Front 17

major outputs from the cerebellum travel out through what

Back 17

superior cerebellar peduncle

Front 18

cerebellum: what are the 3 layers

Back 18

the molecular, purkinje, and granule cell layers

Front 19

molecular layer: where is it, what is it made of, where does it extend to

Back 19

outer layer and is made up of basket and stellate cells as well as parallel fibers which are the axons of the granule cells; the extensive dendritic tree of the Purkinje cell extends into the molecular layer

Front 20

purkinje layer: where is it, what is it made of, where does it extend to

Back 20

middle and most important layer of the cerebellar cortex; all of the inputs to the cerebellum are directed toward influencing the firing of Purkinje cells and only axons of Purkinje cells leave the cerebellar cortex and they have an inhibitory effect on the deep cerebellar nuclei in the cerebellar medulla (so they only signal that leaves is an inhibitory one and, as we'll see, every signal that comes in is an excitatory signal on the purkinje cells)

Front 21

granule cell layer: where is it, what is it made of, where does it extend to

Back 21

innermost layer of cerebellar cortex and contains golgi cells, granule cells, and glomeruli; each glomerulus is surrounded by a glial capsule and contains a granule cell and axons of golgi cells which synapse with granule cells; the granule cell is the ONLY EXCITATORY NEURON within the cerebellar cortex

Front 22

2 major afferents to the cerebellum

Back 22

mossy fibers and climbing fibers

Front 23

mossy fibers: tract, enter cerebellum via what, target and function

Back 23

vestibulocerebellar, spinocerebellar, and corticopontocerebellar tracts; enter the cerebellum via the ICP, ICP and SCP, and MCP (decussate); target is excitatory terminals on granule cells (glutamate which is excitatory)

Front 24

climbing fibers: tract, enter the cerebellum via what, target and function

Back 24

olivocerebellar tract (from inferior olivary nucleus in the medulla); enter the cerebellum via the ICP (decussate); target the excitatory terminals on purkinje cells

Front 25

purkine cells: target, transmitter, and function

Back 25

deep cerebellar nuclei; GABA; inhibitory

Front 26

granule cells: target, transmitter, and function

Back 26

purkinje cells; glutamate; excitatory

Front 27

stellate cells: target, transmitter, and function

Back 27

purkinje cells; GABA; inhibitory

Front 28

basket cells: target, transmitter, and function

Back 28

purkinje cells; GABA; inhibitory

Front 29

golgi cells: target, transmitter, and function

Back 29

granule cells; GABA; inhibitory

Front 30

what are the names of the deep cerebellar nuclei and where are they

Back 30

the fastigial nucleus is in the vermis; the interposed nuclei (emboliform and globose) are in the paravermal; the dentate nucleus is in the lateral hemisphere

Front 31

trace the path of a signal from the dentate nucleus

Back 31

purkinye cell in the lateral hemisphere --> inhibitory on the dentate nucleus --> out to the brainstem where is crosses to the contralateral side and then ascends to the red nucleus where it synapses --> VL and VA of the thalamus where they synapse --> upper motor neurons in the precentral gyrus (influence their firing); keep in mind that sure this tract crosses but it affects the corticospinal tract which also crosses so overall the medulla has its effect on the ipsilateral side of the body

Front 32

vestibulocerebellum (flocculonodular lobe): deep cerebellar nucleus, efferents to what, function

Back 32

fastigial nucleus; efferents to vestibular nucleus; function= changes position of eyes and trunk in response to movement of the head

Front 33

spinocerebellum (intermediate hemisphere): deep cerebellar nucleus, efferents to what, function

Back 33

interpositus nucleus; efferents to red nucleus and reticular formation; function= affects LMNs via reticulospinal and rubrospinal tracts to adjust posture and effect movement

Front 34

pontocerebellum (lateral hemispheres): deep cerebellar nucleus, efferents to what, function

Back 34

dentate nucleus; efferents to thalamus (VA, VL) then cortex; function= influence LMNs via corticospinal tract which effect voluntary movements especially sequence and precision

Front 35

cerebellar lesion signs

Back 35

tremor with intended movement without paralysis or paresis; symptoms associated with cerebellar lesions are expressed ipsilaterally because the major outflow of the cerebellum projects to the contralateral motor cortex, and then the corticospinal fibers cross on their way to the spinal cord; thus unilateral lesions of the cerebellum will result in a pt falling toward the side of the lesion

Front 36

lesions to the vermal region: signs, causes

Back 36

difficulty maintaining posture, gait, or balance (an ataxic gait); pts with vermal damage may be differentiated from those with a lesion of the dorsal columns by the Romberg sign (this is only in in dorsal column lesions pts sway with their eyes closed); in cerebellar lesions pts will sway or lose their balance with their eyes open or closed (visual input doesn't help); anterior vermis lesions are usually the result of degeneration from alcohol abuse and are present with gait ataxia; posterior vermis lesions result from medulloblastomas or ependymomas and present with truncal ataxia

Front 37

lesions to the hemipheres: signs

Back 37

distal musculature; intention tremor is seen when voluntary movements are performed, tremor is absent at rest; dysmetria (the inability to stop a movement at the proper place so the pt has trough with the finger to nose test); dysdiadochokinesia (adiadochokinesia) is the reduced ability to perform alternating movements such as pronation and supination of the forearm at a moderately quick pace; scanning dysarthria is caused by asynergy of the muscles responsible for speech so pts divide words into syllables thereby disruption the melody of speech; gaze dysfunction ocurrs then the eyes try to fix on a point, they may pass it or stop too soon and then oscillate a few times before they settle on the target, a nystamus may be present and directed toward the involved cerebellar hemisphere; hypotonia occurs with an acute cerebellar insult that includes the deep cerebellar nuclei, the muscles feel blabby on palpation and deep tendon reflexes are usually diminished